Digital dash cluster

[iambutch1]

I see this topic never goes away but I haven't seen this answer yet. I have a 1984 vette that I have retuilt. The cluster has been working just fine until last week. My battery was dead so I jump started it. After I got the car started the cluster is now weird.

When you first turn the ignition on the cluster goes through its check and everything cycles fine and looks good. But after it checks itself the speedometer goes to 14 mph and the tach reads nothing. After the car is started the tach and speedometer remains the same, 14 mph and nothing on the tach. The upper portion of the cluster works as it reads oil pressure and temp as well as reflecte the gas level. I would think that the cluster was bad if I didn't see the cluster do its diagonistic.

I figure that there was a voltage surge when I jumped it but I don't know where to look first. I have the cluster out and ther appears to be no burned segments in the circuit boards. I have ordered a tach filter hoping that this might be the problem.

Any suggestions?

Thanks
Mike

 

[Ken Anderson]

Mike,
Here's what went wrong: you jump started your car! When you jump start anything with computers ( better known as microprocessors) you induce a voltage spike. This usually kills a few of the microprocessors in the process, no pun intended. Some of today's cars have a sacrificial relay/fuse that will take the hit and save the rest, yours doesn't. If you jump start your car and REVERSE the polarity, you can cook everything.
Your tach filter won't fix it and you can't see the damage because it happens inside the processor(s). We repair 2 -3 clusters per week and are finding more and more chip problems. Your cluster will have to be repaired/replaced. I know it isn't practical, but a slow charge battery charger is the ticket and I would replace my battery every 3 years, no matter how it checks out, just to have a fresh battery and no problems. If you think you got problem snow, wait til you get a C-5 and start having electrical problems.

 

[iambutch1]

Thanks Ken

Thanks Ken. Your right it isnt exactlly what I wanted to hear but facts are facts. I didn't reverse the polarity but did jump it with another car. I just wanted to get it started as I had an appointment and did what I had to do. The bad thing is how much it will cost to repair my impatience.

Oh well.

Thanks