I need help. I got my ECM(I have a 92 6 Speed) rebuilt by SIA electronics. I installed it today and the security light/service asr/sys flashing all went away. But now the speedometer is acting up. It basically doesnt work, it will show 1 mph for a little bit, then kinda go up to 6 mph, and sometimes will flash something like 27 mph, the numbers are all random. Also my instant mpg is also messed up, which I'm guessing the problem is related. This car is sort of my daily driver so quick assistance is greatly appreciated

BTW: not sure if this is relevant, before I got the ECM rebuilt, the instant mpg worked along with speedo. The car sat for a month or so.

Thanks
-Brandon

Have you contacted the company that rebuilt your ECM? You may find that your problem is something they have experienced before.

I am going to call them tomorrow. I figured that I would check on here first. The rebuild comes with a 1-year warranty.

I think I read elsewhere that the ECM has nothing to do with speedometer. I'm am not 100% on that tho. need someone to confirm that.

I was worried that it may be a speed sensor or something like that, not toally sure. I havnt had the car for very long and I have yet to "experience" the joys of sniffing out problems.

There is a vehicle speed sensor (VSS) on the trans that sends data for the speedometer. Sometimes the plastic gears go bad or could be an electrical connection problem. I'm not exactly sure where it's at, but I believe Bogus is familiar with this and should chime in.

Matthew

Who's saying the ECM has nothing to do with the speedometer? It uses the vss (speedometer) input to determine mpg.

and if the VSS is hosed, then the speedo data and MPG will be screwed.

The speed is converted by the ECM (4k pulses per mile). I wonder if something else is amiss within the ECM.

Does the cruise work? Do you still have a factory stereo? If so, check the SVC feature.

Code 24 is a bad VSS. Check to be sure you inserted the MemCal correctly. If not, it will cause this problem.