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#1 |
All idiot, no savant
Join Date: Aug 2004
Location: The Netherlands, Europe
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![]() Want to calibrate the speedometer of your 240? Here is how!
The speedometer is controlled by a ITT UAF2115 chip. This chip is used in many cars of the same era, including the 7/900 series. There is a calibration resistor in the cluster that will alter the speed shown by the meter. The trip/mileage counter calibration is not affected by this resistor. Parts needed: A normal 1/4 Watt resistor in the 56+ Ohm range, I used 61 Ohm on my 240 to calibrate it. Thin wire. Screw terminal. Solder+desolder wick. Here ya go: ![]() ![]() After you have removed the cluster from the dashboard and removed the speedometer unit itself you'll be greeted by this sight. Shown here is the PCB with the chip and calibration resistor and many other components. The green arrow indicates the calibration resistor. ![]() Desolder here. ![]() The resistor that was in this place was the calibration resistor. I used some thin wire and drilled a hole in the back of the case to mount the resistor outside of the case for easy calibration. When you drill the hole make sure that no shavings are left inside of the cluster that will cause problems later on. The resistor is connected to pin 4 and pin 13 (ground) of the chip. ![]() Here the resistor mounted on a screw terminal thingie. Pro tip: if you need to fix speedometer gear, its helpful if the wire for the calibration resistor can pass through the hole, its helpful of the resistors are connected via such a clamp vs crimped/soldered. The stock resistor is about 56 Ohm. If you increase the resistance value the speedo shows less km/h or mph. On my car i replaced the resistor for 2 in parallel that are ~61 Ohm combined iirc and the results are very good. 50 km/h on the speedo is 48-49 km/h GPS and 120 km/h is 119,5 km/h GPS. ![]() Some data found on the back of the VDO unit. K=6091 Imp/km - 437.204/002/041 Thanks to the Brickboard speedometer calibration article (for 740) and TB member blabla (BTI Volvo modifications) for reminding me of this possibility. Extra: ITT UAF2115 Speedometer and mileage indicator chip datasheet You can change more stuff about how the speedometer reads and the mileage counter works, for example changing the amount of pulses needed etc (page 2, grounding/floating/connecting pin 11 etc). Can be handy for people swapping in ABS rear axles or triggering the speedometer with front axle abs tone ring etc and when swapping between 12/48/96 tooth tone ring stuff. Though I have not tried this yet. Extra 2: More good stuff here: http://cleanflametrap.com/speedo.html Extra 3: Running a Truetrack with homemade trigger wheel now and the later style aluminiu diff cover, works great. Not sure how it works in stock form since I had to adjust sensor clearance anyway (Using a rubber ring or thick gasket sheet is fine). Hope this helps Edit 2: finally fixed the broken links. Things have been crazy here.
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240 | 1991 | 338K Km | B230F+T | Cosworth T3 60/63 | M90 | TrueTrack Husaberg FE450 70 degree '12 mx/supermoto swapped Last edited by JW240; 11-03-2018 at 07:34 AM.. Reason: series/parallel mixup fixed - pics fixxxered |
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#2 |
†John3:16
![]() Join Date: Jan 2009
Location: Dallas
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![]() ugh, would have been nice to know before having to cut teeth and mess everything up.
much appreciated for the write up, Jan.
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#3 |
<Master Tech>
Join Date: Nov 2002
Location: California
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![]() What!? I need to read more about this!
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No Start Thread |
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#4 |
50 shades of beige
![]() Join Date: Jul 2002
Location: Rockville, MD
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![]() wow, awesome article. Will be useful at some point when i am driving a 240 again
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#5 |
the real Towery
Join Date: Sep 2002
Location: VA, USA
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#6 |
Turbobricks Low Life
Join Date: Feb 2004
Location: Portland, Oregon
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![]() You could probably use an adjustable resistor so that you could adjust the calibration on the fly. Just put some sort of 2 pin connector on one of the blank switch panels.
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#7 |
Board Member
Join Date: Jun 2008
Location: The Netherlands
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![]() Me too. Can you tell me more about it. Got a pair laying here.
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‘81 245 |
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#8 |
All idiot, no savant
Join Date: Aug 2004
Location: The Netherlands, Europe
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![]() Open a cluster, look at how pin 2 is connected (ground, connected to +12v or floating) and see from there. I have no idea how it is from the factory. By altering how pin 2 is connected you can alter the speed and mileage displayed/counted by a factor 4, can be enough to go from 12 to 48 tooth for example (depending on which multiplier is selected from the factory).
The front ABS tone rings probably give the same signal level as the rear axle sensor. In theory it should work. Someone needs to test it. Last edited by JW240; 06-22-2011 at 08:35 AM.. |
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#9 |
Tbricks MIG Welding Champion
Join Date: Mar 2005
Location: Suomen Åbo
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![]() Hey, good info here.
You say that this has no effect on the trip or mileage meter? That would be good news, because i've been thinking about how to use the 220 km/h speedometer face together with a 200 km/h electronic speedometer. The turbomodels had a cable driven speedo that reached to 220 km/h as standard, but i need to use an electronic speedo from a late model 240 (no speed output gear on the transmission that's being used) in my factory turbo, so in theory i might be able to use that face and the adjust the resistor value to get a correct reading. BTW, you state that you used 2 resistors in series, but in the picture they are in parallel, are they not? Not that it matters in my case, but anyway. Thanks for sharing. This is great.
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![]() Cops pulled me over. Papers, they said. Scissors, i replied. Still i did not win. Go figure.
Last edited by Wagner; 06-22-2011 at 09:07 AM.. |
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#10 | |
All idiot, no savant
Join Date: Aug 2004
Location: The Netherlands, Europe
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![]() Quote:
well, if you want to use the 220 km/h speedometer face, then you probably don't need to calibrate the speedo much ![]() I'd like the 220 km/h speedo face as well but they are hard to come by (only seen it once) and the finish is different from the 89/90? and up matte finish. In the datasheet of the chip they state that the calibration resistor between 4 and 13 only has effect on the galvanometer, not the stepper motor for the mileage meter. I never tested it but the trip meter seems to be the same as before I think. I always like it when there is a simple solution with simple/stock parts for these little issues. No need for complicated stuff. yeah good call on the series/parallel mixup, must have been late when i typed it ![]() |
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#11 |
Board Member
Join Date: Feb 2003
Location: Sunny Socal
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![]() Good info, any one adapt an electronic speedo to an early (pre 81) cable driven instrument cluster? Ive got a 79 dash in my 86 240 truck with an M46 from a 700, no speedo gear, but ive still got the speedo sensor wiring in the car. I can get an OD with a cable output, but i dont wanna, lol
Mark
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1995 E320 wagon AMG 3.6 swap <-- Daily driver 2009 Honda Fit <-- Wifeys ride 1959 Austin Healey Sprite <--something completely different (my project) 1974 Fiat X1/9 <--Mom's little toy (next project) 1982 Olds Custom Cruiser LQ4 <--Dad's beast (current project) "Driving the old 2 valve 740 is a bit like driving an IKEA wall unit, so leisurely is its acceleration, so angular its lines." My former brick saved my life 6/25/03....Volvo for Life |
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#12 |
Board Member
Join Date: Nov 2008
Location: Charlotte, NC
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![]() Old thread -- perhaps we can revive. Is there a late model 120 mph electric speedo that I can transplant into my '82 cluster to replace the cable driven unit?
JW240 - a few things; go slow with me and talk like I'm a second grader. ![]() The good news about this is if it will work, I can hook the whole thing up temporarily in the car while I'm driving, calibrating, checking against GPS, etc. And once I get it right - then I can transplant into the cluster.
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'82 242 6.2L; '17 Mazda3; '16 CrossTrek |
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#13 |
Board Member
Join Date: Feb 2009
Location: SF bay area
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![]() love the info... great work.
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#14 | |
All idiot, no savant
Join Date: Aug 2004
Location: The Netherlands, Europe
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![]() Thanks!
Quote:
Not sure if i understand you correctly but the unit in the first 2 pics is the speedo unit itself, pulled from the cluster. You can slightly see the face plate too. The 3rd and 4th pic are taken with the cluster assembled again of course. I do not know of a way to affect odometer reading with this chip, but it has been a long time since i have read the datasheet. Maybe. Setting the odo higher with the speedo unit removed from the cluster can be done quite easily, the dials-numbers can be rotated if you are careful. At least, thats what i´ve done to some speedo´s that i took apart. One thing i realized after looking at the pics is that a small piece of shrink wrap to cover the resistor(s) isnt a bad idea, the exposed wire could make a short if the screw terminal thingie accidentally comes loose from the cluster. |
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#15 |
Board Member
Join Date: Nov 2008
Location: Charlotte, NC
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![]() Thanks JW -- we'll see where I end up!
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#16 |
Newbie
Join Date: Jun 2017
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![]() Planning to do this, do you happen to still have the pictures? Atleast the one that points out the right resistor do change.
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#17 |
All idiot, no savant
Join Date: Aug 2004
Location: The Netherlands, Europe
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![]() I still have them, need to re-host.
But wont have acces to the pics this week. Maybe Art's site can help you with the chip pinout, you can trace it. In a few weeks i can have the pics up again. |
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#18 | |
Newbie
Join Date: Jun 2017
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![]() Quote:
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#19 |
Newbie
Join Date: Jun 2017
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#20 |
Board Member
Join Date: Nov 2017
Location: Houston
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![]() My car currently shows 40mph when I'm going 48. I would love to have this live!
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#21 | |
bruspeed
Join Date: Apr 2006
Location: Sacramento, CA
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![]() Quote:
I glued the pot behind the plug for the clock adjust stalk hole, and can adjust mine without removing the cluster. I used something like this, multi turn trim pot. https://www.frys.com/product/5976914...H:MAIN_RSLT_PG
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1980 242 Turbo 2004 V70R ![]() |
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#22 | |
What, me worry?
![]() Join Date: May 2003
Location: Acworth, Ga. USA
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![]() Quote:
The other choice would be to swap the whole cluster from a late model. Has anyone done this?
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I coulda had a V8! |
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#23 |
Board Member
Join Date: Sep 2003
Location: Retirement Village, Sydney
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![]() I’ve got an ‘87 cluster in my 242GT with ‘81 dash. Got sick of the cable speedo actuation after 3 different cables all failed to be the right length (Supra 5spd conversion). It works using a Toyota mechanical-to-pulse adapter which came off something Japanese & obscure, and an aftermarket adjustable pulse-counting-and-conversion kit (speedo “tuned” off ‘phone & SatNav GPS
![]() With the ‘81 cluster it works fine, with the ‘87 cluster there’s some cross-wiring which I haven’t been arsed hunting-down. The “Acc” setting for the (new) switch (replaced the switch with brand-new one before it occurred to me the problem could be incompatibility between clusters) has the effect of the “On” setting, so I basically don’t have an Accessories setting. Apart from that, the majority of it just plugged in, including at least the two big whacky-shaped plugs. Speedo plug is obviously custom though, that won’t be plug-and-play. The car drives fine, and everything works as expected for the “On” ignition-switch setting.
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When I'm cruisin' in overdrive ... Don't have to listen to no run-of-the-mill talk jive. Shatner: The Colonel is breakdancing ... gimme a break!! Rollins: Credit terms raised! Shatner: I can't get behind any of that! Shatner: I can't get behind so-called singers that can't carry a tune, get paid for talking, how easy is that? Well, maybe I could get behind that ... Rollins: Well, I can't!! |
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#24 |
Sh*t pot stirrer
Join Date: Jun 2016
Location: Keizer, OR
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![]() Anyway to get the pictures to work? About to embark on this task on the Wife's cluster.
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-Stephen -My car: White 1991 244, 330k miles. B230F LH2.4, AW70, R134a retro -Wife's car: White 1990 244DL, T cam, 200k miles.B230F LH2.4, AW70 w/aux cooler, Virgos, tow hitch -PSM 2002 Subaru WRX wagon: EJ205, 5MT, 120k miles, Perrin TBE Rebuilding EJ207 shortblock to swap in this summer. -1997 Subaru Legacy Brighton: EJ22, 5MT, 236k miles |
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#25 |
Board Member
Join Date: May 2011
Location: Land of Enchantment
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![]() Would be very interested in seeing these pics. Thanks so much for doing this write-up!
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Feedback: http://forums.turbobricks.com/showthread.php?t=268935 Parts For Sale: http://forums.turbobricks.com/showthread.php?t=296466 |
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