First of all, thanks for everyone for being a part of this very invaluable community and hey there, just registered.

2nd, before starting this thread I did my search here and on other resources as well.

I'm messing up with this Del Sol here and having speedometer issue. Most of the time it never goes over 20kph, but sometimes (once in a week on a hot car it will reach 40-60kph top). Everything else on the gauge works well, odometer and trip are fine.

Here is what I've did so far:
I've unplugged the VSS, cleaned the connector, run the DMM tests for conductivity and signal. I'm getting less volts then direct measure on my battery on the VSS signal. The ground and signal output is ok when driving very slowly. I've did a full dissasemble of VSS, cleaned-up and polished the connectors and pins. Should I have exactly the same voltage as measured directly on the battery clamps or slightly lower voltage at the VSS is ok (I think it was around 10)?

At the gauge on my connector harness I'm getting solid 0 to 4.75v pulses when the car is driving slowly. Is that enough (should I have 5v here)?

On my gauge cluster board and speedometer PCB I've checked all the connectors and lines for conductivity, did thorough visual inspections and found no issues whatsoever. The under dash fuse is also ok.

Unfortunately, I don't have any replacement gauge or vss nearby to narrow down the source of the problem. I also want to diagnose it while having fun with educating myself.

Yep, the next step I'm going to do is to resolder all joints on speedo pcb to see if that helps. If that fails, I'm buying new speedometer/cluster whichever comes first. Did I miss anything before I touch my wallet?

Again, thanks for all the awesome data you've gathered here, folks.

 

Does the CEL work? Is code 17 thrown?

 

Forgot those details: no CEL thrown, works ok (unplugged VSS and waited CEL to popup)

 

Swap in a known good speedometer.