Carrera51

Any guidance would be appreciated. Did a search and only found threads on 2.5 NAs describing a similar issue.

I purchased an 89 S2 that hadn't run in 5 years due to a broken intake camshaft (it's fixed and found why I think it broke but that's a for another thread). Anyway, after the engine was fixed along with a TB/WP service, and some other work, the car is running great but the tach does not work. All the other gauges in the pod function as they should. No tach bounce when starting the car so it's like it isn't getting any power. The previous owner said it worked fine when the car was on the road. He had begun taking it apart before it turned into the stalled project it was when I purchased it. I checked the connector at the back of the distributor after being told that's where it gets tach signal. That connector is connected. I followed the wire back to the front of the engine where it splits off and goes to the back of the distributor and it's intact.

If anyone has any ideas where else I should look to make sure things are as they should be, I will appreciate it.

walfreyydo

There are places you can send to have them attempt a repair (recommend a google search), but in the end I just went with a used cluster from ebay.

If you are experienced with electronics you can try resoldering all the joints and inspecting/replacing the transitors and capacitors and so forth. Unfortunately the complexity of the tachometer system leads to not a lot of support/DIYs on repairing these, at least based on my research when I was in your position.

Example of a tachometer repair place you could try sending it out to:
https://www.nhspeedometer.com/
https://www.bobsspeedometer.com/services/tachometers/

Carrera51

Thanks for the reply. I am stumped as to why it worked when the car was parked and now doesn't work now that the car is running. I am going to try swapping in another cluster and see what happens but I am thinking something isn't connected somewhere. One of my friends who has owned a couple of these said to check the connection up behind the brake booster where the car harness plugs in and also by the ECU.

walfreyydo

Mine was intermittent, not working, driving, then all of a sudden RPM's reading, few minutes later dies, so on and so forth. Likely a cracked solder connection or similar. Likely repairable but not sure if a used cluster (~$200 ebay) would be cheaper than repair (unknown cost). New tach extracted from used cluster solved my issue.

Jfrahm

Same here. On one of my cars the tach died, replaced it with one from a used cluster.

dillon410021

one plug to check is the one by the dme. Its a separate plug on engine harness. Not sure if s2 is different, this was on 88 8v

Christopher Zach

Just saw this: My tach works, but my speedometer jumps to 150+mph every time I turn the key on. My guess is a blown transistor inside of it.

Wonder if you could get a signal generator and try sending pulses to it and see what happens.