420A 97 GS manual - speedometer issues (not VSS)

[ShadowOxide]

First time posting - let's get to the nitty gritty:

- 1997 GS 5 speed
- ECU/OBD is showing VSS and matches GPS speed, so I am getting a correct speed signal
- Speedometer randomly started jumping all over, now it sits at 45mph and occasionally bumps up to 80 and back to 45 when driving. Pulled speedo out, no weird looking caps.

Has anyone attempted fixing a busted speedo board? Do we know what kind of signal and voltage I need to simulate to check things out? Considering this route because I also have a 92 Supra and eventually I'll want to learn how to triage and repair old boards more. I can easily get a replacement, but for the hassle I'd much rather slap in a GPS speedometer and be done with it forever. Someone offered me a known working speedo for $75, but I'm meh about another one dying eventually. Old cars, amiright?

 

[Sirius1995]

for me it was the plastic white big gear in the gearbox, you can see it under the VSS when you take it out, it's attached with 2 plastic clips but you need to take transmmission out to fix it

 

[ShadowOxide]

for me it was the plastic white big gear in the gearbox, you can see it under the VSS when you take it out, it's attached with 2 plastic clips but you need to take transmmission out to fix it

If that was the case, my ecu would not see the correct speed signal from the VSS, which is why I mentioned that as part of my diagnostics.

 

[Sirius1995]

If that was the case, my ecu would not see the correct speed signal from the VSS, which is why I mentioned that as part of my diagnostics.

oh yea that is true, my b