Incorrect speedometer reading?

Nine times out of ten it will be the vehicle speed sensor (VSS). There is a chance the cluster needs to be rebuilt or the PCM is not processing the data correctly as well but let's stick to the easy and most obvious stuff first. There are two different transmissions so here is the location of the VSS so you can check them out. Check out the images (below). Let us know how it goes.

I absolutely could not afford the 8-hour job to replace the input and output sensors in the transmission. I sent in my gauge cluster to be repaired as I have several indicator lights that don't come on during the indicator light test when you first start the truck, and I hoped maybe my speedometer issue maybe was there somehow. My cluster came back completely gone through with a note from the repair guy that it was already completely functioning, but they went through it anyways. My mechanic put it back in and I still don't have most of my indicator lights. A test drive showed the speedometer still off. He reached out to GM and the tech was not at all sure why my speedometer was off his only suggestion was to try re-setting the ECU. When plugged in to do so it showed green checks for everything, but my mechanic still checked all and reset it. My speedometer is now correct. However, I still don't have most of my indicator lights including the check engine light. Is there an easy way to test/check to find the cause of them not lighting up during the indicator lights test?

I am glad you got the speedo working correctly, that is a rare problem, thanks for letting us know. We only handle one problem per thread, please post your new question here, you must be logged in.

https://www.2carpros.com/questions/new

Cheers, Ken

I absolutely could not afford the 8 hr job to replace the input and output sensors in the transmission. I sent in my gauge cluster to be repaired as I have several indicator lights that don't come on during the indicator light test when you first start the truck and I hoped maybe my speedometer issue maybe was there somehow. My cluster came back completely gone through with a note from the repair guy that it was already completely functioning but they went through it anyways. My mechanic put it back in and I still don't have most of my indicator lights. A test drive showed speedometer still off. He reached out to GM and the tech was not at all sure why my speedometer was off his only suggestion was to try reseting the ecu. When plugged in to do so it showed green checks for everything but my mechanic still checked all and reset it. My speedometer is now correct. However I still don't have most of my indicator lights including the check engine light. Is there a easy way to test/check to find the cause of them not lighting up during the indicator lights test?