Hi all,

During my troubleshooting on a completely unrelated issue, I accidentally disconnected the wire to the VSS on my '97 Grand Prix. I reconnected it, and went on to something else.

Once I had my wheels back on I drove, like normal, for a good 20 or so km. Out of nowhere, my engine started to surge, tranny stopped shifting, got an engine light and the speedometer went dead. Confirmed with my OBD-II scanner, I got a code of P0502, Vehicle Speed Sensor (VSS) Circuit Low
Input.

I thought the cable got loose so I pulled the front passenger wheel off and checked; it was still on. I reseated the connection and took a short test drive. Things were working fine for about 10 minutes, then back to having a dead speedo and no shifting. The drive home was long, with intermittent working of the sensor.

That was last night. This afternoon I just finished unhooking the connector, spraying the pins on the connector and sensor with electrical cleaner, and reassembling.

Did a test drive and within 2.5 km the speedo went dead and I lost shifting.

I'm really wishing I hadn't even touched that connector The car has never had this issue before. I don't think it's the sensor because it does work, at least for a while after a reseat. The wiring is also unlikely for the same reason.

Am I missing something?

maybe a case learn? not sure. Do me this one favor for my own curiosity: pull the VSS connector, reconnect the VSS connector. Pull the negative battery connection and let it sit for about half an hour, maybe an hour. Other than that, I see what the others have to offer. Good luck with the hunt.

Is the plug nice and snug? You may have damaged a wire or the plug when you undid it the first time.

I took a much closer look at the connector and compared it to similar ones, like the MAF between the throttle body and air filter. Yep, it was damaged. The lighting I was using before just wasn't enough to get me to see it.

It is now repaired and things are working great again. Thanks for all your help =)

Not a problem. Glad we could be of some help.