home register FAQ memberlist calendar

Go Back   Turbobricks Forums > Mechanical > maintenance & nonperformance

Reply
 
Thread Tools Display Modes
Old 05-22-2013, 07:09 PM   #1
jalp4u
Newbie
 
Join Date: May 2013
Location: Michigan
Default Very strange cluster/charging issue NEED HELP ASAP

I'm trying to fix my brothers stock 1990 Volvo 240 (Non turbo) but it's got me beat and I really need help, it's a 240DL wagon and I have all the wires correct going to the alternator and the cluster. The problem is that the small red wire going to the alternator isn't putting out battery voltage. I tried testing it as a positive (one end of the tester to a ground and the other to the wire) and got nothing, so I tested it as a negative (put one end on the + side of the battery and the other on the small red wire) and got about 12 volts. I also noticed that my headlights are always on no matter what now. None of the gauges in the cluster work now aside from the clock and every time I turn the key on the overdrive light comes on and stays on when I start the car, but I'm able to turn it off by pushing the overdrive button. I know all the lights are good in the cluster and if I take that small red wire and touch it to the + battery wire on the back of the alternator (B+), the battery light comes on. The high beam lights work and so does the light for them on the dash, but that's about all that works in the cluster. When I pull the hand brake, the light for it doesn't come on and no light comes on when I turn the key on aside from the overdrive light. I tested the small red wire for any breaks by disconnecting it from the firewall and alternator, then sent power through it and checked the battery wire to see if any voltage from the small red wire was getting to the battery wire and it wasn't, but just to be extra sure, I left it disconnected and ran a whole new wire directly from the blue wire behind the dash, but it still wasn't charging and the cluster still wasn't working as it should. Now here's the really strange part... When I start the car and connect a wire from D+ to B+ on the alternator, the RPM of the motor drops but I still don't get anything but battery voltage even when I rev the motor. How I figure it, whatever is causing the cluster not to work right is also causing the charging system not to work right. I know the alternator is good, it's a reman and I just got it a few days ago because I assumed my old one was bad. I took the ground off the battery while the car was running and it died. I didn't have the old one tested first, just got the new one and it did the same thing, so I had it tested and it passed 8 times, putting out 14+ each time. I even tried changing the computer and still nothing. Any idea what could cause this issue? I have to have this car running properly by this Sunday or my brother will lose his job. I've been at it for days (sun up to sun down) and it's got me beat.

I seem to have narrowed it down to this red cylinder thing under the cluster, behind the dash... I looked it up and it's a "bulb failure relay" or "bulb failure warning sensor"...

The reason I think this thing is at least part of the problem is because I've tested the wires as I've mentioned above and they are good all the way to the firewall. I tested the red wire at the red relay sensor thing and it tested the same as it did at the back of the alternator (as I mentioned above) when everything was connected. However, the blue wire coming from the ignition worked as it should. No power until the key was turned and when the key was off it also tested as a negative and changed to a positive when the key was turned on. I'm not 100% sure it's bad, but from my understanding, the blue wire turns into the red wire at that point, but the blue is + and the red tests as - for some reason when the key is on. Maybe something else could cause this relay/sensor to behave this way? Maybe it's something else that I haven't found yet? It is missing the driver side marker light and turn signal and every time he would hit the brakes, the light failure light in the cluster would come on, but that doesn't come on anymore. For this system to randomly fail seems odd to me... If you need anymore details, let me know.

Any thoughts, help and input on this matter are greatly appreciated!
jalp4u is offline   Reply With Quote
Old 05-22-2013, 07:39 PM   #2
TrickMick
Broad Member
 
TrickMick's Avatar
 
Join Date: Jan 2011
Location: norte carolina
Default

not even gonna try...get some OUTSIDE HELP....
*hopefully* you haven't completely fried the cluster and the alternator....
you've done just about everything you COULD DO to trash a charging
system and several SENSITIVE components...PLEASE....get someone w/good
electrical chops to help you ON SITE...it is mo bettah to WATCH AND LEARN
as a technician w/the correct tools and experience sorts / helps you....

perhaps on of the "TBrix crew" will come to help...post your location (just the city is fine)
and do some "private messaging" to arrange for "eyes on the ground"...
do NOT feel that it's a jab at your skills or any such - "lektronix" are the hardest part
of sorting these old beauties and it DOES take EXPERIENCE to "do the right things" /
in order / and w/the correct connections...

" Electrons are STUPID....they know to do ONE THING.....
they follow the path of least resistance - and they do THAT
at the speed of light...." I have not yet met a person fast enough to halt
that process once it has begun...
__________________
In a closed society where everybody’s guilty, the only crime is getting caught. In a world of thieves, the only final sin is stupidity.
TrickMick is offline   Reply With Quote
Old 05-22-2013, 09:11 PM   #3
jalp4u
Newbie
 
Join Date: May 2013
Location: Michigan
Default

Quote:
Originally Posted by TrickMick View Post
not even gonna try...get some OUTSIDE HELP....
*hopefully* you haven't completely fried the cluster and the alternator....
you've done just about everything you COULD DO to trash a charging
system and several SENSITIVE components...PLEASE....get someone w/good
electrical chops to help you ON SITE...it is mo bettah to WATCH AND LEARN
as a technician w/the correct tools and experience sorts / helps you....

perhaps on of the "TBrix crew" will come to help...post your location (just the city is fine)
and do some "private messaging" to arrange for "eyes on the ground"...
do NOT feel that it's a jab at your skills or any such - "lektronix" are the hardest part
of sorting these old beauties and it DOES take EXPERIENCE to "do the right things" /
in order / and w/the correct connections...

" Electrons are STUPID....they know to do ONE THING.....
they follow the path of least resistance - and they do THAT
at the speed of light...." I have not yet met a person fast enough to halt
that process once it has begun...

I live in Detroit and welcome anyone that's willing to help... I tried to take it to the only shop near me (within driving distance of the cars current state) and he said he didn't have time to look at it and to bring it back next week (I then helped him install a trans in a BMW for free). I asked a tech about it online and he pretty much told me to do everything I did aside from disconnecting the ground from the battery while the car was running and my dad is the one the said to do that, I trusted him because he's been working on cars since before I was born. So, I only did what I was told to do. However, the problem doesn't seem to have change since it was first noticed. If I've damaged anything, I can't tell. All I can do is take the alternator off and have it checked again to be sure it's alright. If I somehow cooked the computer, I have another one I can replace it with...unless that one is somehow bad too.

I sure would like to know what caused this problem in the first place. At first I thought it was the alternator seeing as I installed a stereo system and told him not to turn it up and told him the volume limit before causing too much stress on the alternator, I just figured he didn't listen. So I replaced it and the problem didn't change at all. Had I not assumed, I would've had the old one tested just to be sure. I never in my wildest dreams thought that this car would have such a complex issue without warning.
jalp4u is offline   Reply With Quote
Old 05-22-2013, 09:58 PM   #4
atomicthumbs
Board Member
 
atomicthumbs's Avatar
 
Join Date: Mar 2011
Default

Quote:
Originally Posted by jalp4u View Post
I have to have this car running properly by this Sunday or my brother will lose his job. I've been at it for days (sun up to sun down) and it's got me beat.
You may wish to quickly start making arrangements to buy a beat-to-****, working car from someone if you need the car that soon. It sounds like your electrical problems will be a bit hard to fix!
atomicthumbs is offline   Reply With Quote
Old 05-22-2013, 10:08 PM   #5
TrickMick
Broad Member
 
TrickMick's Avatar
 
Join Date: Jan 2011
Location: norte carolina
Default

here is a site (done by a Camp TBrix fellow fettler):
http://www.k-jet.org/documents/greenbooks/200-series/

and here is another (*ALSO* done by a forum member):
http://www.volvowiringdiagrams.com/

for information of a "general nature try THIS site:
http://www.autoshop101.com/
the "technical articles" are TOYOTA *FACTORY TRAINING MODULES* for Toyota
dealership "line techs"....they will be a GREAT help in your understanding of "what's
going on" as you observe and learn whilst someone goes after your problems...
go ahead and get the alternator TESTED but *DO NOT INSTALL IT* until the OTHER
ISSUES have been resolved (no reason to cook another one...) HOPEFULLY
someone will chime in that can be of ON SITE assistance...if you are
UNSURE about the whys and wherefores of the world of 'lektrikal majik' then
STOP now and re-group...

if I were younger and closer we'd do a "rallye for the dead 240" and get it sorted
tout de suite....I'm too old and cripped up to do an 18 hr road trip *AND* be
able to think clearly at arrival....at about 10 hrs behind the wheel I have to draw
the shades 'cause I rapidly become *ZOMBIE MAN*....
TrickMick is offline   Reply With Quote
Old 05-23-2013, 01:25 AM   #6
Bensin
Garrett whine rules
 
Bensin's Avatar
 
Join Date: Oct 2011
Location: Portland de Oregon
Default

It's hard to say what kind of hornet's nest you have, if any!

Step back and Look up the wiring diagram for the car. There are only 3-4 wires going to alternator: make sure they are going to the right connections. That seems unknown, so know it's certain.

Don't assume your reman alternator is good! Out of the box alternators can be junk.

In the first paragraph you said "I took the ground off the battery while the car was running and it died." I think, not certain, that's BAD (meaning BAD). Maybe someone else can confirm.

And I really hope someone out there in Michigan will help you out!
__________________
Stage Zero Is A Smooth Machine (I'm not a racer but I play one on TB) 1986 740 Turbo wagon
Bensin is offline   Reply With Quote
Old 05-23-2013, 07:14 AM   #7
jalp4u
Newbie
 
Join Date: May 2013
Location: Michigan
Default

Quote:
Originally Posted by Bensin View Post
It's hard to say what kind of hornet's nest you have, if any!

Step back and Look up the wiring diagram for the car. There are only 3-4 wires going to alternator: make sure they are going to the right connections. That seems unknown, so know it's certain.

Don't assume your reman alternator is good! Out of the box alternators can be junk.

In the first paragraph you said "I took the ground off the battery while the car was running and it died." I think, not certain, that's BAD (meaning BAD). Maybe someone else can confirm.

And I really hope someone out there in Michigan will help you out!

I've been looking at the wiring diagrams for about 2 days now and so far the charging system is wired correctly. I followed it from the point that the blue wire behind the dash became red, to the back of the firewall and down and around the crank to the alternator and everything there is in the correct place. Just to be clear, Blue - ground goes to an alternator casing bolt, Large red - goes from B+ on the alternator to the starter motor and from there goes to the battery, Small red - goes from D+ on the alternator to the charge light and is the exciter. Also in the loom with the battery wire and exciter wire is a black wire that goes to the side of the block and is for oil pressure if I remember correctly off the top of my head... Lol I just woke up.
I had it tested 8 times the same day I got it because when I installed it didn't charge. I tested that with a volt meter first. If you're charging system works properly, you should be able to take the ground wire off the battery while the car is running, the RPM will fall just a tad for a second and then pick back up as it will be running off the alternators power and normally that doesn't hurt anything, but if someone knows that it does for a fact, I'll go with that. I've also cleaned all the fuse holders with sand paper and all the fuse ends, just be be sure they are all getting good contact and I normally do this about once every 6 months or whenever I notice discoloration. I've also went to junk yard where you pull your own parts and pay for them, but they didn't have any Volvo's with compatible parts. Oh, one more thing I should mention. This isn't the original motor and trans... My dad managed to lock up the motor that came with the car... I still have it, but I had to put a new one in. It came with the trans and a computer. I installed the motor and trans myself and it's held up without any issues so far, but somethings has been wrong with trans since I got it... He has to let off the gas for it to shift into 3rd and 4th (I just manually shift it at the proper speed and it's fine), but it's been like that for about a year now and he's been driving the crap out of it since then. I was always planning on doing a swap, just waiting on the opportunity and that would've been this summer had I not run into unexpected expenses... (starts and moon need to line up and all that jazz lol). I wonder if somehow the overdrive circuit is causing this problem... It's the only light that comes on with the key. There was nothing wrong with the old trans, I should probably put it back in now that he's not driving the car.
jalp4u is offline   Reply With Quote
Old 05-23-2013, 07:33 AM   #8
jalp4u
Newbie
 
Join Date: May 2013
Location: Michigan
Default

Quote:
Originally Posted by TrickMick View Post
here is a site (done by a Camp TBrix fellow fettler):
http://www.k-jet.org/documents/greenbooks/200-series/

and here is another (*ALSO* done by a forum member):
http://www.volvowiringdiagrams.com/

for information of a "general nature try THIS site:
http://www.autoshop101.com/
the "technical articles" are TOYOTA *FACTORY TRAINING MODULES* for Toyota
dealership "line techs"....they will be a GREAT help in your understanding of "what's
going on" as you observe and learn whilst someone goes after your problems...
go ahead and get the alternator TESTED but *DO NOT INSTALL IT* until the OTHER
ISSUES have been resolved (no reason to cook another one...) HOPEFULLY
someone will chime in that can be of ON SITE assistance...if you are
UNSURE about the whys and wherefores of the world of 'lektrikal majik' then
STOP now and re-group...

if I were younger and closer we'd do a "rallye for the dead 240" and get it sorted
tout de suite....I'm too old and cripped up to do an 18 hr road trip *AND* be
able to think clearly at arrival....at about 10 hrs behind the wheel I have to draw
the shades 'cause I rapidly become *ZOMBIE MAN*....
Thanks for the links, they did help fill in a few blanks. I had the wiring diagram for the car saved on my phone already, that way I can look at it while I'm looking at it lol.
One more thing I should note... The car has been sitting since the 21st at 5pm. I'm going over there today to clean up the grounds and see if anything has somehow drained the battery. If it's not raining too bad, I may swap out the trans.

I've made that trip before, I know what you mean lol, I went right to sleep soon as I got home. I made that trip in January actually and I was coming from Florida. I didn't know people down there don't know how to drive in snow lol. It was all nice and sunny out and then about 3-5 inches of snow was on the ground within an hour and all the traffic on the highway stopped and this was at 1pm... We didn't get to move again until about 12m. Lol it looked like something out of a movie, a helicopter landed on the highway too lol I thought for sure zombies would be coming out the woods next!
jalp4u is offline   Reply With Quote
Old 05-23-2013, 01:48 PM   #9
smokeyfan1000
Guest
 
Default

Could have a failed printed circuit board on the Instrument Cluster. Rare but can happen

Also might have a damaged main engine wiring harness. But the 90 -93 240 MEWHs don't give the problems the 80-88 MEWHs did (had biodegradable wire insulation on them...yep bad juju there.
  Reply With Quote
Old 05-23-2013, 04:09 PM   #10
atomicthumbs
Board Member
 
atomicthumbs's Avatar
 
Join Date: Mar 2011
Default

Quote:
Originally Posted by Bensin View Post
In the first paragraph you said "I took the ground off the battery while the car was running and it died." I think, not certain, that's BAD (meaning BAD). Maybe someone else can confirm.
Well, my 940's manual says that disconnection of the battery while the car is running will "immediately destroy the generator and electronic equipment", or something along those lines.
atomicthumbs is offline   Reply With Quote
Old 05-23-2013, 04:13 PM   #11
jalp4u
Newbie
 
Join Date: May 2013
Location: Michigan
Default

Quote:
Originally Posted by smokeyfan1000 View Post
Could have a failed printed circuit board on the Instrument Cluster. Rare but can happen

Also might have a damaged main engine wiring harness. But the 90 -93 240 MEWHs don't give the problems the 80-88 MEWHs did (had biodegradable wire insulation on them...yep bad juju there.
I thought of that too and that's why I pulled it out and inspected it myself, but I didn't look at is as closely as I would've liked to, so I didn't screw it back in place, just plugged it back in to run a few more tests. The odometer had stopped working at some point last year at 253k miles and he been driving it pretty much everyday since then and all over south east to mid Michigan, so if I had to guess, I'd say it's somewhere around 300,000+ miles, but I fixed that while I had it pulled out. The little clear plastic nub that the holds the other end of that little spring had broken off, so I pulled the spring out the little slot and stuck a small steel shaft through the hold of the spring to prevent it from going back into the slot. I'm not sure if it works because I haven't driven it and I'm pretty sure if speedometer isn't working, the odometer won't work also. It's been raining all day, so I didn't bother going over there to mess with it seeing as I'll have a few nice days starting tomorrow.

Sure would be nice to have some on site help, but I can't wait for the world to change nor am I holding my breath lol. I'll pull the cluster and get a closer look just to be sure and if needed, I can solder any breaks I find. If it checks out ok or if I fix it and it doesn't fix the issue, I'll put the other trans in and if that doesn't fix it, I'll have to try to find another light failure sensor or another volvo 240 or 740 to see if the one I have works and if that checks out fine, I'll check all the other relays.
jalp4u is offline   Reply With Quote
Old 05-23-2013, 04:26 PM   #12
jalp4u
Newbie
 
Join Date: May 2013
Location: Michigan
Default

Quote:
Originally Posted by atomicthumbs View Post
Well, my 940's manual says that disconnection of the battery while the car is running will "immediately destroy the generator and electronic equipment", or something along those lines.
http://www.youtube.com/watch?v=lT7L7A4M_1o

And it didn't self destruct omg?! lol
jalp4u is offline   Reply With Quote
Old 05-23-2013, 04:29 PM   #13
TrickMick
Broad Member
 
TrickMick's Avatar
 
Join Date: Jan 2011
Location: norte carolina
Default

Quote:
Originally Posted by atomicthumbs View Post
Well, my 940's manual says that disconnection of the battery while the car is running will "immediately destroy the generator and electronic equipment", or something along those lines.
you are correctemundo... HERE IS THE 1990 vOLVO 240 owners manual:
http://www.volvoosad.com/Manuals/240_1990.pdf


from page 75 OF THIS PARTICULAR SCAN......
direct quote: " Volvo 1990 240 Model
Never disconnect the battery circuit (for example, to change the battery) while the engine is running, as this will immediately ruin the alternator. Always make sure that all the battery connections are cleaned and properly tightened. "

c'mon guys... SOMEBODY has to be imbued w/the "spirit of Woodward Ave"....

used ta do wheelies out of the lot at the Totem Pole...my brand new
Sapphire blue XLCH....damn I be old!
TrickMick is offline   Reply With Quote
Old 05-23-2013, 04:56 PM   #14
jalp4u
Newbie
 
Join Date: May 2013
Location: Michigan
Default

Quote:
Originally Posted by TrickMick View Post
you are correctemundo... HERE IS THE 1990 vOLVO 240 owners manual:
http://www.volvoosad.com/Manuals/240_1990.pdf


from page 75 OF THIS PARTICULAR SCAN......
direct quote: " Volvo 1990 240 Model
Never disconnect the battery circuit (for example, to change the battery) while the engine is running, as this will immediately ruin the alternator. Always make sure that all the battery connections are cleaned and properly tightened. "

c'mon guys... SOMEBODY has to be imbued w/the "spirit of Woodward Ave"....

used ta do wheelies out of the lot at the Totem Pole...my brand new
Sapphire blue XLCH....damn I be old!
It puts a very heavy load directly on the alternator as it's running everything in the car without the battery as a kind of cushion, so yes, it'll ruin your alternator if you let it run like that for long just as if you ran it with a bad battery but as for it spontaneously combusting, it won't do that lol. However, the important thing to gather from that quote is that it doesn't say you'll ruin anything other than the alternator.

I cruised Woodward in this Volvo lol and the next year I cruised Gratiot in a 1987 10 second turbo Buick lol, good times. http://youtu.be/cyVfNRZnNk8
jalp4u is offline   Reply With Quote
Old 05-23-2013, 05:11 PM   #15
TrickMick
Broad Member
 
TrickMick's Avatar
 
Join Date: Jan 2011
Location: norte carolina
Default

Quote:
Originally Posted by jalp4u View Post
It puts a very heavy load directly on the alternator as it's running everything in the car without the battery as a kind of cushion, so yes, it'll ruin your alternator if you let it run like that for long just as if you ran it with a bad battery but as for it spontaneously combusting, it won't do that lol. However, the important thing to gather from that quote is that it doesn't say you'll ruin anything other than the alternator.

I cruised Woodward in this Volvo lol and the next year I cruised Gratiot in a 1987 10 second turbo Buick lol, good times. http://youtu.be/cyVfNRZnNk8
*NICE BUICK*! (heh, heh, heh.....NOT "a granny car" by ANY stretch)
ah YESSSSS...the "sleeper GN" WE4 BAD BOY....just enough extra scoot
to suck the doors off a GN as you went by.....*IF* ia can ever find the
"Blue on Biscuit" Special Edition 1993 245 I want you can bet yer ass that
an "LSx and a beefy Autoslik" will end up motivating it...stock HEIGHT /
tubbed rears w/ a serious locker and half shot NOX....ooohhhhuuuuhhhhhh
I'm gettin' all dizzy....

the bad thing about the "pull the wires w/the engine running" is the CURRENT SPIKE
that hits post yank as the "ground FLOATS and the alt goes looking for a
place to dump the excess....

carry on laddie....
TrickMick is offline   Reply With Quote
Old 05-24-2013, 02:38 PM   #16
jalp4u
Newbie
 
Join Date: May 2013
Location: Michigan
Default

Just took my cluster apart and checked everything with a tester and all is well. A relay I installed under the dash where there was no relay was causing the headlights to stay on no matter what, I pulled that out and it fixed it. Headlights work normally now. Still no change in the behaviour of the cluster or charging system... but whatever it is happens after the connection on the firewall, so its something wrong behind the dash for sure, but I don't know what and it isn't the cluster. What could it be???
jalp4u is offline   Reply With Quote
Old 05-24-2013, 03:51 PM   #17
smokeyfan1000
Guest
 
Default

If your HLs are working as supposed to, *but then go off by themselves*, and won't come on when it does this, *unless you pull the hi beams on* with the Hi/LO beam/T/S stalk, then you need a new "Main Relay" (as the parts book calls it.)

It's just a regular looking cube 12v relay similar to others used on the car. But it does have it's specific p/n IIRC. And you notice a K painted on it's top in *blue*.

On my 91 240 ,this relay is behind the center dash console with a few other relays. Sometimes you'll find it hanging by it's wires because a previous mechanic has replaced it,& did not relocate it in the OEM spot, for easier access the next time it fails

IN which case you may be able to access it by pulling the DS center dash console side panel off.

AND... FWIW,Volvo moved this relay to different locations over the production years of 1986-93 cars. Also if this relay fails other weird HL operation scenarios *might* be possible. Example: 1986 245 has it behind the brake pedal, mounted high to floorboardMost all report what I 1st described though.

Last edited by smokeyfan1000; 05-24-2013 at 06:35 PM..
  Reply With Quote
Old 05-24-2013, 04:26 PM   #18
jalp4u
Newbie
 
Join Date: May 2013
Location: Michigan
Default

Quote:
Originally Posted by smokeyfan1000 View Post
If your HLs work then go off by themselves, and won't come on when it does this, *unless you pull the hi beams on* with the Hi/LO beam/T/S stalk, then you need a new "Main Relay" (as the part book calls it.

It's just a regular looking cube 12v relay similar to others used on the car. But it does have it's specific p/n IIRC.

On my 91 this relay is behind the center console with a few others. FWIW,Volvo moved this relay to different locations over the 86-93 years. And also if this relay fails other weird HL operation scenarios *might* be possible.

Most report what I 1st described though.
Head lights work as they should. I just don't understand why the overdrive light comes on when I turn the key on but goes off and on with the button as is should. No other light in the cluster comes on with the key. Whatever the cause it seems to be inside the car or the trans seeing as the o/d light comes on with the key...
jalp4u is offline   Reply With Quote
Old 05-24-2013, 06:36 PM   #19
smokeyfan1000
Guest
 
Default

Quote:
Originally Posted by jalp4u View Post
Head lights work as they should. I just don't understand why the overdrive light comes on when I turn the key on but goes off and on with the button as is should. No other light in the cluster comes on with the key. Whatever the cause it seems to be inside the car or the trans seeing as the o/d light comes on with the key...
All the warning lights should illuminate when key is 1st turn on to ACC position and to the start position, then go out when engine starts, *IIRC*
  Reply With Quote
Old 05-24-2013, 06:48 PM   #20
jalp4u
Newbie
 
Join Date: May 2013
Location: Michigan
Default

Quote:
Originally Posted by smokeyfan1000 View Post
All the warning lights should illuminate when key is 1st turn on to ACC position and to the start position, then go out when engine starts, *IIRC*
I know, but the overdrive light is the only one that comes on and I've tested all of them. The overdrive light doesn't go off until I turn the key off or turn it off with the button on the gear selector. Any idea what could cause that? None of the gauges are working also.
jalp4u is offline   Reply With Quote
Old 05-24-2013, 08:21 PM   #21
cleanflametrap
Board Member
 
cleanflametrap's Avatar
 
Join Date: Sep 2009
Location: near baltimore
Default

The exciter voltage for the alternator comes from the same place your gauges and warning lamps get their power. In a 1990 240 this begins at the ignition switch as a blue wire to the L-shaped plug on the speedometer gauge.

From there it immediately leaves the gauge on one of the three inter-board pins to a piece of flexible circuit I've named the "flex fuse" screwed to the main cluster board.

From there, it returns to the speedometer gauge and splits off to the warning lamps, temp and fuel gauge power (voltage stabilizer) and through the battery light leaves the cluster on the round plug in a red wire headed for the alternator.

If you don't have any warning lamps OR gauges, this power is missing. Use a test lamp to trace it through, while all the plugs are plugged in and the load is present.

Here's a map of the 240 charging system drawn so you can follow the entire circuit.



And here are a couple links to physical points on the cluster where you can track this 12V you need for the exciter.

http://cleanflametrap.com/cluster14.jpg

http://cleanflametrap.com/cluster15.jpg

One other misconception to clear up: The alternator supplies all the car's power needs when it is running. In addition to that, it re-charges the battery, which is only there to start the car.

However, the battery serves as a fairly good voltage limiter, so the advice to not disconnect it with the motor running (as used to be the common way to test a charging system) is good advice in the event the alternator and its regulator fail to limit the voltage due to a fault.

So maybe 9 out of 10 times (meaning in 9 of 10 samples) there will be no damage doing what you did. Batteries and their terminal connection fail frequently without this collateral damage to ECUs, airbag controllers, diodes, etc.
__________________
-Art
cleanflametrap is offline   Reply With Quote
Old 05-24-2013, 08:27 PM   #22
Simi
Upsetti Spaghetti
 
Simi's Avatar
 
Join Date: Jan 2012
Location: Orlando, FL
Default

Your cluster issue...

I had that happen to my car the first time I EVER did work to it. I installed the tachometer and nothing lit up or worked except the OD light. Check the wires leading to the cluster for any issues. Try disconnecting and reconnecting all of them again and clean the contacts.

I simply removed it, disconnected all the wires and reconnected it and everything has worked since. Maybe its just a old wire and all you need to do is just mess with it.
__________________
1989 240 Turbo
1988 745 Turbo - SOLD
1991 940SE - SOLD
1995 850 T5-R
1991 740 Turbo
1987 240

Leave Me Feedback
Simi is offline   Reply With Quote
Old 05-24-2013, 09:29 PM   #23
jalp4u
Newbie
 
Join Date: May 2013
Location: Michigan
Default

Quote:
Originally Posted by cleanflametrap View Post
The exciter voltage for the alternator comes from the same place your gauges and warning lamps get their power. In a 1990 240 this begins at the ignition switch as a blue wire to the L-shaped plug on the speedometer gauge.

From there it immediately leaves the gauge on one of the three inter-board pins to a piece of flexible circuit I've named the "flex fuse" screwed to the main cluster board.

From there, it returns to the speedometer gauge and splits off to the warning lamps, temp and fuel gauge power (voltage stabilizer) and through the battery light leaves the cluster on the round plug in a red wire headed for the alternator.

If you don't have any warning lamps OR gauges, this power is missing. Use a test lamp to trace it through, while all the plugs are plugged in and the load is present.

Here's a map of the 240 charging system drawn so you can follow the entire circuit.



And here are a couple links to physical points on the cluster where you can track this 12V you need for the exciter.

http://cleanflametrap.com/cluster14.jpg

http://cleanflametrap.com/cluster15.jpg

One other misconception to clear up: The alternator supplies all the car's power needs when it is running. In addition to that, it re-charges the battery, which is only there to start the car.

However, the battery serves as a fairly good voltage limiter, so the advice to not disconnect it with the motor running (as used to be the common way to test a charging system) is good advice in the event the alternator and its regulator fail to limit the voltage due to a fault.

So maybe 9 out of 10 times (meaning in 9 of 10 samples) there will be no damage doing what you did. Batteries and their terminal connection fail frequently without this collateral damage to ECUs, airbag controllers, diodes, etc.
Alright, I'll try that first thing in the morning. Thanks for the info! I have a question that you may be able to answer also. I'm looking at the ignition wiring diagram and at the bottom of it there is a blue wire going to a "transient surge protector"... Where is this located? I see it's connected to the same blue wire that goes to the "speedo (inst clstr)" speedometer (instrumentation cluster), so I was wondering if this may have something to do with any of this and if it does, is it like a normal surge protector that you can reset if it's been tripped?
jalp4u is offline   Reply With Quote
Old 05-24-2013, 09:40 PM   #24
jalp4u
Newbie
 
Join Date: May 2013
Location: Michigan
Default

Quote:
Originally Posted by Simi View Post
Your cluster issue...

I had that happen to my car the first time I EVER did work to it. I installed the tachometer and nothing lit up or worked except the OD light. Check the wires leading to the cluster for any issues. Try disconnecting and reconnecting all of them again and clean the contacts.

I simply removed it, disconnected all the wires and reconnected it and everything has worked since. Maybe its just a old wire and all you need to do is just mess with it.
I've taken it out a lot of times already, but it wouldn't hurt to clean up the connections a bit just to be sure.
jalp4u is offline   Reply With Quote
Old 05-24-2013, 09:50 PM   #25
cleanflametrap
Board Member
 
cleanflametrap's Avatar
 
Join Date: Sep 2009
Location: near baltimore
Default

Quote:
Originally Posted by jalp4u View Post
Alright, I'll try that first thing in the morning. Thanks for the info! I have a question that you may be able to answer also. I'm looking at the ignition wiring diagram and at the bottom of it there is a blue wire going to a "transient surge protector"... Where is this located? I see it's connected to the same blue wire that goes to the "speedo (inst clstr)" speedometer (instrumentation cluster), so I was wondering if this may have something to do with any of this and if it does, is it like a normal surge protector that you can reset if it's been tripped?
Huh? What drawing?
cleanflametrap is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On

Forum Jump


All times are GMT -4. The time now is 12:28 PM.

Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2019, vBulletin Solutions Inc.