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240 aftermarket radio

mschultz373

mschultz373

Member
Joined
Mar 11, 2020
Location
dirty coast
I have an aftermarket Kenwood stereo installed in my 240 and it died about a month or two ago. I am just getting around to trying to fix it. here's the unit - it's the kind that has a detachable front-face with the unit behind it:

<a href="https://ibb.co/QmPChLd"><img src="https://i.ibb.co/x51fwWH/stereo.jpg" alt="stereo" border="0"></a><br /><a target='_blank' href='https://imgbb.com/'>free pic hosting site</a><br />


so I am getting 7.3V on each of the pins that connect to the front face. I assume that that means the front-face is dead - since the front-face won't turn on when plugged in. I have not torn the whole center console apart to check the wiring to the amp down below, but I removed the center cover near the windshield and it looked like the wiring to the Kenwood unit was pretty clean.

does it seems reasonable to conclude the front-face is dead or not? if not, how should I proceed troubleshooting?
 
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Then again you could send it out for repair.

I had a stock head unit in an older exotic car I once owned that stopped working; in that instance it made sense to repair it, to keep the car original.

So off it went to La Jolla Audio in San Diego: $600.00 later it was working just fine.
 
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this is the wiring to the unit. I am getting ~2.4V off the thicker grey wire that is the power wire, I assume. does that value check out?

<a href="https://freeimage.host/i/JWwm3F"><img src="https://iili.io/JWwm3F.md.jpg" alt="JWwm3F.jpg" border="0" /></a>
to my very amateur eye, this doesn't look too bad of a wiring job and it appears like I could drop in any stock 8-pin unit?
 
With the bezel off and key on, try pressing the tiny little Reset button on the main unit. Does the blue[?] led on the main unit blink? If not, try wiggling the wiring harness and see if it comes back to life. If the blue led is blinking, try re-installing the faceplate and go around a corner at a time pushing it inwards to see if you can get it to respond. You can also try electronic contact cleaner on the main faceplate connector.
 
i am getting just under 12V to the red wire (tho its not in the position pictured by koyte). no shorts as it is reading the same voltage from the original 6-post terminal all the way to new 8-post terminal.

tried resetting the unit without effect. I think it's just dead. it was about 2 years old.... things just don't last.
 
i ordered a new unit, but now I wonder - do I need to replace the stock amp in my car if I want to wire in some speakers at the rear deck? i only have two speakers as of now, in the front doors. 4" speakers. unless the rear speakers are buried under the door trim....

did factory 85 240 DLs come with 4 channel amps that would enable this?
 
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alright, more trouble. ordered another kenwood unit, it has the same 8-pin configuration so i can use the currently installed adapter - and it won't turn on.

I am getting 12.8V at the red ignition wire with ignition on. I am getting 17.5 V at yellow constant with car off, 20.8V with ignition on.

Given these specs check out, is my grounding wire the clear issue?

Fuse #1 and 8 are both good - radio fuse and antenae power respectively.
 
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mschultz373 said:
alright, more trouble. ordered another kenwood unit, it has the same 8-pin configuration so i can use the currently installed adapter - and it won't turn on.

I am getting 12.8V at the red ignition wire with ignition on. I am getting 17.5 V at yellow constant with car off, 20.8V with ignition on.

Given these specs check out, is my grounding wire the clear issue?

Fuse #1 and 8 are both good - radio fuse and antenae power respectively.
Click to expand...

Make sure the harness is wired correctly per the manual? Just because the plugs look the same doesn't necessarily mean the pins are (although they probably do match...)

Also, 17.5 and 20.8 sounds way higher than it should be. Are you sure that's correct? Is your alternator voltage regulator busted?
 
no, i am just a n00b and had a bad ground. occured to me after I walked a bit. remeasured and the problem is the constant power. it's reading 3.5-4V instead of 12V. so I'll have to dig in there and see where the problem is.
 
tore everything apart and the constant power wire is running to some coil behind the brake pedal/foot air vent?? it's spliced off a red wire to a 10A fuse and then up. but even at the fuse, the originating wire is only reading 3.5-4V???
 
Glad it sounds like a relatively minor wiring problem!

mschultz373 said:
tore everything apart and the constant power wire is running to some coil behind the brake pedal/foot air vent?? it's spliced off a red wire to a 10A fuse and then up. but even at the fuse, the originating wire is only reading 3.5-4V???
Click to expand...

A 10A fuse inside the fuse panel? Do other fuses read 12V? I bet high resistance caused by corrosion. Trace the connections backwards until you find 12V and then clean the contact points from there up to the radio.

If 10A fuse outside the fuse panel - I would try to identify and clean it up, of course, but I would also try and get the connection moved into the fuse panel if reasonably possible.
 
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