Electrical malfunction

gmc
canyon

#1

One morning the truck wouldn’t start. Even with the key removed, the needles on the instrument panel twitched and buzzed like dying flies. Mechanic solution is to replace the entire instrument panel due to its cluster being bad. Does this sound right?


#2

It sounds more like guessing at the problem to me. Until the problem area has been confirmed by using proper testing methods I wouldn’t replace anything. There are a lot of shops around that really don’t have the skilled techs needed for problems like this. If the tech is guessing at the problem area then it will cost you more in the end for needless parts replacement and extra tech time.

I would first suspect a faulty ignition switch causing the trouble. Another possible trouble spot is the alternator may be backfeeding power to the electrical system due to a faulty blocking diode. If removing the wiring to the alternator solves the trouble then you most likely will need to replace it.


#3

A low battery can cause all kinds of weird gremlins with modern computer controls, including electronic gauges. Was the battery bad or low, and has the problem with the gauges gone away?


#4

We had a similar problem in a GMC Sonoma. The first issue was determined to be a bad door switch for a battery drain, but the gauges 20 seconds after turning off the engine gauges would activate. Off to the dealer, new instrument cluster, still the same symptoms, the dealer referred to level 2, level 2 that is normal. Look for a battery drain first.


#5

The mechanic attached a handheld gauge to the battery which showed normal range charging when the engine was running. When turned off, the battery would hold a charge for several hours and turn over as normal. No buzzing of instrument panel when key is removed. But after setting overnight, a turn of the key results in nothing. The gauges seem now to be still.


#6

Thanks for the language to use with the mechanic. I spoke with him again and he says he’s certain it is the cluster. Said he’d “eat” the cost if it wasn’t. We’ll see.


#7

So, did you keep the new cluster, and live with twitching needles, or did they end up replacing something else? Did you end up replacing the battery or could it be fully charged?