[ronsherwood]

I'm hoping someone else will have run across this problem and found a good fix. I did a search, and couldn't find another topic that really matched mine. In my '90 Sierra, the speedo will occasionally just drop down to zero while I'm driving. If I reach up and thump the instrument panel lens (sometimes takes several thumps) the speedo will come right back up. I thought the problem was in the speedo itself, so got one form Pick-N-Pull and swapped it in, no change in problem. Pulled the cluster to check connections, all the connections were clean and appeared solid. That was as far as I could go, I'm no electronics tech, and I wasn't about to start getting into the diodes, resistors, and computer chips of the printed circuit board. Any suggestions out there?

 

[ASTE25]

So, are you saying the replaced the complete cluster assembly with a used one?

 

[ronsherwood]

Just replaced the speedo itself. All the rest of the gauges work fine. I'm kind of steering myself toward the printed circuit board, since thumping the panel brings it back up, which takes the speedo sender out of the picture in my mind.

 

[SStruck]

MaxTorque, did you ever resolve this issue? I'm having the EXACT same problem and it's drivin me crazy!

 

[ronsherwood]

Haven't fixed it yet. Talked to local Speedo shop, they also said it sounds like the circuit board. I plan on going to the local pick and pull and taking a chance on another circuit board, as they quoted me $200+ to send mine off for repair.