Speedometer and odometer doesn't work

[Campelo]

Hello everybody,

My speedometer and odometer doesn't work ,they seem to be dead.
I've replaced the last 500mm of cable before de sensor. Also remove and clean the sensor and looks good. But they still don't work.
Any other idea?
I expected that if neither (spedo + odo) worked, the problem was the cable...

thanks in advance.

[Brianmoooore]

I expected that if neither (spedo + odo) worked, the problem was the cable...

In 95% of cases, that will be true...... that leaves 5% for other reasons.

Disconnect the white plug from the instrument cluster and connect a meter on a resistance or continuity range between pin 8 (brown wire) and pin 12 (brown/red wire), then move the car along a few feet so that the rear wheels turn. (Car will start and run with cluster removed)
The meter should alternately show short circuit and open circuit several times for each complete turn of the wheels.

[Campelo]

Thanks a lot! In case the signal is correct, will the problem be in the cluster? If it is not correct is it possible that some other section of cable or sensor broken (although it did not seem as it changed the value of ohm ...)??

Thanks again

[Brianmoooore]

If the signal is reaching the cluster plug, then the cluster itself will be the chief suspect.
There's a common fault where the solder cracks on the pins of the speedometer circuit board where it plugs into the main circuit board, but this is usually an intermittent fault, sometimes working, and sometimes not. The connections between the white socket and the circuit board can also crack if someone has tried to remove the white plug in the past, without lifting the locking bar.

[Campelo]

Perfect Brian, really good advices. I will try tomorrow and come back with a feedback.

[Brianmoooore]

Check fuse 12 is OK as well, although if this was blown it should affect the radio as well.

[Campelo]

Hello Brian/everybody,

I checked the white plug as you mentioned and the meter showed short and open circuit alternately (also different ohm values changing the meter to ohms). So I supose that the cluster is the problem. I removed it.
Can someone show me some pictures with the points that I should check (in the cluster)??

Thanks in advance.

[Brianmoooore]

Open up the cluster, remove the screws on the back of the case behind the speedometer, and pull the speedo. assembly out. The electrical connections to it are by four(?) metal pins which you will have pulled from a small black plastic socket. It's the soldering of these pins to the speedo. circuit board that is prone to failure. Also check the soldering of the socket for the white plug, where it joins to the main circuit board.
Nothing to do with the fault you have, but while you're in there: There is a small rectangular box moulded into the plastic of the back of the cluster casing, near the temp. gauge. Locate the area on the main circuit board directly inside this, and you will see two soldered joints holding the component inside the box. These joints will either be in need of resoldering, or will already have been resoldered at some point.

[Campelo]

thanks a lot Brian. I’ll do it this week! You have earned some ​​beers hahaha. thank you Brian

[BenHar]

Nothing to do with the fault you have, but while you're in there: There is a small rectangular box moulded into the plastic of the back of the cluster casing, near the temp. gauge. Locate the area on the main circuit board directly inside this, and you will see two soldered joints holding the component inside the box. These joints will either be in need of resoldering, or will already have been resoldered at some point.

These ones?

https://www.e30zone.net/e30wiki/index.p ... sistor.jpg

Ben

[Brianmoooore]

That's them!

[Campelo]

Hello again,

I've just removed the speedometer and everything looks good. Attached some pictures. Could you please mark the points that I should check? I have the welder ready.
All the welds looks to be good, but im not an electronic expert. Some welds points (marked in the pictures maybe have liquid??)
Thanks in advance.


Regards,