troubleshooting code 24 (VSS) on a 1987 R10 Chevy Suburban 350 TBI

[skizzik]

Originally Posted by clinkerclint

Sorry to bring up a dead post but my 88 chevy one ton/350/AT has the exact same issues. Stall at light throttle and the speedo either does not work or bounces. Did you get the stumble fixed?

Yes, I eventually realized that the computer was flashing a VSS error. When this happens, the engine doesn't know that the computer is moving and tries to maintain constant idle (I think that's how it works), which causes all the trouble. Here's what I suggest:

- is your speedometer working reliably? If not, you're probably getting a VSS error. I believe it's a code 24 of the service engine soon light.
- could be that the speedometer cable needs replacing, could be that your vss sensor is faulty or isn't reporting to the computer, or could be that the speedometer driven and/or drive gears are stripped and need to be replaced. This last option (the speedo gears) is what I'd investigate first if you're speedometer isn't working at all, as those gears do wear out over time. What caused my problem was a tranny mechanic put the drive gear back on the drive shaft in the wrong spot after rebuilding my tranny, which meant that the drive and driven gears weren't even touching.

On my suburban, the speedo cable plugs right in the back of the speedometer. If yours is the same way, you can unplug the speedo cable and watch it while you drive and see if the cable turns. If the cable looks like it's turning like it should, the problem is with the speedometer or the vss sensor itself.

Hope this helps.