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Team 928 I have a 1986.5 that I am working on and having issues with the speedo springing to life at about 30-40 mph. I followed Dwaynes post but I think I have a different board then him. I pulled the cluster and cleaned all the leads with deoxit but its still not working, I either have to tap the cluster and it will pop to life or it will kick in about 30-40mph. Ive been following Dwaynes instructions on rennlist but Im at a point where I may be over my head. Before I start pulling the plastic circuit board Im looking for any advice on other ideas as to why it would be doing this. Everything else on the cluster, including odometer, works great its just this jumpy speedo.
I have the wiring diagrams and Im going to check continuity. Was hoping to test at least the speedo continuity from the cluster connection to the board. Also wondering if anyone recognizes my board, I wonder if I am missing a rivet (last one below the line of 3 in pics) looks like maybe a rivet missing? Could that cause it?
I would suggest you remove the speedometer from the cluster clean the pins that press into the back use deoxit 100 on the pins and make sure to fit the rubber spacers that are on the back of speedo as well
Thx! Is it possible you have a picture to reference the areas you are talking about? This is internal so not connected to the plastic board correct? Thx again!
-Steve
First remove the screws that go around the periphery of the gauge cluster
next identify where the speedometer is and look on the backside
and youll see four screws that hold the speedometer in
there flat blade screws
close to the center of the screws youll see theres some round crimps and those crimps are attached to pins that go through the white portion of the gauge housing
after you have removed the four screws for the speedometer turn the whole unit so its facing cluster housing down on a towel and carefully lift off the see-through side then carefully lift out the speedometer from the gauge cluster housing
watch out for the black spacers they are rubber theyre pressed on to the anchor pins on the backside of the speedometer
you also will see the metal pins that engage the speedometer cluster unit
Put deoxit on these and the slots on the speedometer
No now is a good time to replace the speedometer gear if it hasnt already been done
Last edited by Mrmerlin; Aug 21, 2021 at 06:20 AM.
Thanks so much, I didnt deox the pin connections inside the speedo at first and when I put it all back together it was worse, and my odo wasnt working!! After some initial panic, I re-did it again and I also tightened the pins at the connection and its working really well. I will check on that wire to the radar detector and try to pull it, hard to tell what is/isnt stock and dont want to make it worse.
Follow the instructions in Dwayne's writeup for checking the four solder joints at the back of the speedo on the PCB with an ohmmeter. I've had to resolder those on more than one car to restore accurate speedos.
Update;
Since the solder job is done, the speedo now works perfectly but .my odometer is not working, trip odometer goes extremely slow and mileage is not counting up. Also my up shift light appears to not be working (light test good, flickered once on test drive) is it possible I damaged something on the board which is causing the odo to not get power or is more likely a gear problem.
kicking myself because I had a small problem that i fixed by creating a bigger problem!
did you replace the speedo drive gear?
If you did,
did you cycle it for about 10 revolutions after you installed it to verify the gear was burr free as it was meshing with the other gears?
Does the odometer number stack rod have any side to side play this can also cause the gears to bind.
This can be fixed with a small piece of wire.
for a picture read the thread i linked. post 53
NOTE a fresh gear can have a small burr on it,
an this is enough to jam the unit its not uncommon to find this.
I didnt replace the gear but it was done about 5 years ago. Do you think that could be it? It was working fine before I started working on the speedo issue. The trip ODO does go up but extremely slow, maybe a tenth for every mile. I am wondering if its electrical? Is that possible??
I would take the speedo apart and check the gear for burrs,
put a drop of machine oil in the number rods, so the wheels are free.
its possible the rod could be rusted
Ok will do. Thank you. Any thoughts on power? Ie is speedo power separate from ODO power or do they both get power from same source (I thought speedo was purely magnetic?)
One thing I didnt mention is my upshift light is no longer working either, it flashed the last time I tested it but never worked after. Also seemed sort of half lit during my last test drive. Wouldnt come on to alert for shift but appeared to be dimly lit, didnt come off until I stopped and removed keys. I checked bulb last week and it was fine so I dont think its a bulb issue.
post the year of your car,
, and a WTB request
See if anyone here has a good used speedometer or a proper year full cluster they are willing to sell,
any shop will probably do the same thing , and it could cost 3 times as much ,
928 INTL might have a used part call them if you dont want to post a WTB request
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Speedo help please
