Jimmy Singh

Hi,
my odometer doesn’t work at all and my speedometer go haywire .

when I release my throttle , the needle goes mad . Speed is the same but needle is spiking staying I am going 100mph when I am going only 40 mph.

anyone has this issue and how you rectified it

Thanks

Rocket Rob

Odometer failures are easy to fix. There is a plastic gear that fails. They are $25 and take about an hour to replace. Unfortunately, there are two standard sizes of gears. You need to disassemble your speedometer to determine which one you need.

http://www.odometergears.com/product...1-964+89-93/70

As for the other symptom, you may need to send the speedometer off to a specialist like Palo Alto Speedometer and might as well have them fix the odometer gear while they have it.

John McM

Jimmy, you PM’d me back in April with the same issue. It would help if you detailed what you have checked and therefore eliminated as a cause.

M3Porsche964

With your symptoms I would ensure the electrical contacts at the back of the speedometer AND on the trans are well established...as well as any fuse. The speedometer itself is pure electrical while the odometers are mechanical running off a small electric motor. I had my odometers go out but the speedometer continued to work which is why I failed to recognize that the gear inside the unit had failed....the very small gear. I replaced both gears but now the odometer works and is accurate but the trip odometer does not..and I have left it alone. I lost maybe 300 miles total but logged this loss into the repair log so anyone in the future realizes that. If you go the gear replacement route....only replace the one that is bad...likely the very small plastic gear...which I replaced the larger one too which was not failed...I think that is the culprit as to why by trip odometer does not work...a definite DIY job for sure...

John McM

It could be a combination of items here. The OP also mentioned a spoiler issue in another post, although that may have been a friends car.

It’s a simple system. The speed signal is taken off the transmission or ABS sensor, depending on the model year, and then used for the speedo, odometer and spoiler controller. Seeing how those three behave is a pointer to the problem(s). To me the jump in speedo speed is a sign of an issue with voltage supply or the speedo itself. The speedometer just converts pulses into current that moves the needle. It’s unlikekt to be the input as the pulses can’t just jump like that. I would send the speedo off for testing as a first step. You will go around in circles otherwise. You need to know what is working correctly to identity what isn’t.

Jimmy Singh

Thanks for all you replies .

my spoiler was faulty and I managed to fix it .

It’s now controlled manually to raise it up and down .

- fuse , could you please let me know which fuse needs to be replaced ?

- power voltage , that’s an interesting idea . Which part do I have to change or what do I do . Pardon my ignorance .

- we opened the speedometer and nothing was broken

- any idea how to I get the odometer to work again ?

- gearbox , is there a speed sensor there ? Isn’t it ok the ABS ?