FireDemonSiC

Ever since I first bought my car it has been randomly spitting a code 24 (VSS). Now it doing it almost religiously and since I am doing major repairs in the next month (Replace spark plugs, torque converter and transmission), I figure It's time to kick this problem.

How does one go about fixing a malfunctioning Vehicle Speed Sensor?

rgarcia63

The VSS doesn't sense the speed directly from the transmission it gets it's input signal from the Speedometer behind the instrument cluster.

FireDemonSiC

The the little yellow box on the back of the cluster is the actual speed sensor. Good to know. I thought it was just a relay or control device.

Now, in the event of a code 24, is this usually the actual sensor itself that has gone bad (I replaced the entire cluster sensor and all, and it still have the code. The cluster and speedo work perfect but it was used so I will not eliminate the possibility of a second bad sensor), or can there be another underlying problem setting the code?

rgarcia63

I believe VSS is used for the TCC and for idle operation. It's possible the ECM isn't getting the signal from the VSS. A data log should show the mpg irractic, but I don't know what parameters/limits have to met to produce a code 24.

JamesC

iTrader: (5)

If the wheels aren't moving when the code sets, disregard it (that according to the GM shop manual). The light in my 85 used to come on if the car idled too long, but would go out after a block of driving.

JamesC

MTXaudioSYSTM

i had the same problem. and my speedometer wasn't reading. it came unplugged some how from the tranny. plugged it back in and all is good for now.

JamesC

iTrader: (5)

Your car would have an electronic speedo with a tail shaft mounted VSS, not so with an 85, which would have been cable driven.

JamesC