speedo only goes to 25

**mach2mack** · 08-12-2011, 05:31 PM

i just picked up a 00 trans am for my new toy problem is my speedometer says im going like 25-30 on the freeway the car started out as a automatic but was switched to a m6 would this be why? any suggestions? thanks

**cammed goat** · 08-12-2011, 05:46 PM

Vehicle speed sensor could be messed up. I think it's located in the transmission. I could be wrong though.

**pajeff02** · 08-12-2011, 07:04 PM

Cammed is right -- on the auto the VSS is mounted on the passenger side of the transmission towards the back. Not a clue where it is at on a T-56 or what the differences are. May simply need to update something in the tune, or it could be a parts incompatability issue.

**35th-ANV-SS** · 08-12-2011, 10:57 PM

I am pretty sure it's because on the T56, the VSS in the tailshaft has a different pulse rate than that of a 4L60E's VSS. The 4L60E has a 40 tooth reluctor ring with 40 pulses with each drive shaft revolution while the T56 uses a 17 tooth. The output shaft diameters are different along with the VSS itself.

I thought there was an adapter you can buy. I could be wrong though. If not, I think you have to use the 4L60E reluctor ring, which would mean you need to pull the tailshaft from the T56 and swap it out. Then change the speedometer conversion in the PCM.

**mach2mack** · 08-13-2011, 06:18 PM

So far the info I have found says the 4l60e trans uses a reluctor ring with 40 teeth and the t56 has 17 teeth could this be fixed by reprograming the PCM ?I can't seem to find a clear answer. anyone on here done a a4 to m6 swap ? I don't really like driving without a working Speedo lol I wouldn't have thought it would be so hard to find a clear answer lol

**cammed goat** · 08-14-2011, 09:29 AM

There are members with auto-to-manual swaps. If the PCM needs to be reprogrammed, and you don't want to get into all the work yourself, you could try your local dealership to connect a Tech II scanner to do the reprogramming.