Hello, I have a 94 3.4 V6 camaro. Recently the car tranny (4L60-E) started acting up. It would just randomly drop out of gear and if I stopped and tryed to go it would be in second gear going nowhere fast. Had it scanned and code "72-signal loss at speed sensor" came up. Got the sensor replaced and a fluid change and a few days later the same problem and same code. Weird thing is that if I pull over and shut off the car and restart it the tranny is fine until the next time it wants to start acting funky. I have had bad experiences with shops just randomly changing parts and eventually telling me that the computer needs to be replaced only to find out that the problem is still there. Has anyone had this problem and/or have any ideas what or where the problem may be before I am at the mercy of the dealer and spending thousands for there mechanic to be guessing whats wrong. Sorry for the long post just trying to give as much info as possible. Any help would be greatly appreciated. BTW great forums.

 

The VSS lives on the transmission tailshaft and is connected directly to the computer with a yellow and a purple wire. It replaces the old spedometer gear, and is used by the computer to determine output shaft speed. The computer uses this data to drive the speedometer, antilock brakes, TCC application. Being that the VSS was replaced, the only other components are the computer and the connecting wires. Of the two , the wiring is the most likely suspect.

Could be a bad connection due contamination or just a bad connector, or a break in one of the wires. Clean the connector out , check that all wires in the connector are tight and that the connector makes good contact with the VSS. On the computer end the wires become part of harness A pins A31 and A32. You can pull out the harness connector from the computer, do a visual inspection and spray the connctor with electronic contact cleaner. Also feel along the wires checking for what may be a break. Do not uravel the harness as this may create more problems.

 

Forgot to mention, there may be more trouble codes stored than DTC 72 and all of these should be investigated before attempting any repairs. Or you may be attemting to fix something that is not broken. or as they say in the computer world, shooting a ballon.

 

you have a p0500 trouble code which means there is a broken wire leading to the vehicle speed sensor or the vehicle's pcm is not correctly installed for the actual tire size on your car. the possible thing to do is to reset the code. then check all the wiring, cables and voltage.