Car:
Stock 88 Formula Firebird
305 TBI, Automatic
Electronic Speedometer

Problem:
I've owned this car for about 3 years now and the speedometer has never worked. The previous owner put in a junkyard computer and removed the VSS Buffer. I purchased a new VSS buffer directly from Pontiac and the speedometer still doesn't work. The SES light comes on at around 50mph and I get a code 24 (VSS Circuit), which means the ECM is looking for a signal and not receiving one.

Other than that the car runs fine. There IS a sending unit on the trans and also wires coming from it. I don't think the previous owner messed around with that, but it's always a possibility.

Any help is greatly appreciated.

 

Assuming he did not change wiring or mess with the ECM it is possible that the transmission VSS sender is bad. You really should try to get to the root of it, VSS affects EGR operation, trans TCC lock. I would start looking at ECM numbers, make sure he has the correct prom, wiring pin by pin to and from the ECM as well as from the buffer and VSS sender at the trans.

 

I have a electronic speedo VSS ill send you for the price of shipping. Just to help you out. I bought a trans from a 92 camaro with electronic speedo and I have no use for it. I just swapped tailshafts. I have it if you want to send me like 5$ or so. PM me.