I have an 84 crossfire the dash has always been a little weird but lately i've notice some weird surging in the voltage while rolling the widows to completely closed. Sometimes for some reason when the windows are all the way shut but i still have the electric to them it will make the rpms act funny and surge the dash lights. I've also notice this with the turning signal that when it palsies so does the dash. Does any one have any ideas, could it be an alternator problem? My instrument panel does have the voltage measurements and when the cars running the volts read close to 15 every time maybe 14.8 or around in that area. I've recently taken out the horn because it was dead just to through that in if it could effect anything i have not a clue.


'84 corvette crossfire (78,4xx mi.)
a/c smog delete
k&n filter /hypertech chip
true duel and muffler deletes

 

Could be several things, but assuming the battery is putting out normal voltage levels, here are the top 3 (general) possibilities:

Grounding:
Refer to the FSM and in particular you'll want to pay attention to the ground lugs to which several of the electronics, including the dash circuitry in particular, depend on a good connection.

Connections:

There is a rather large buss connector on the back of the cluster board. I have seen these connections become severely corroded or "frosted", due to reaction with the atmosphere. (I would replace them or use a contact cleaner to restore them as much as possible before applying a spray coat of connector protectant on the contacts. (Dry contacts...It's just a matter of time!)

Voltage Regulator:

The voltage regulator is located within the alternator. By measuring the voltage WITH A DIGITAL VOLT METER CONNECTED ACROSS THE BATTERY TERMINALS while revving the engine, should not affect the voltage more ±2-3 tenths ( will normally be 14.7 if under-hood temp is "cold", or about 13.8 if under-hood is hot after an extended run.

Now, the voltage regulator also depends on the field current which is provided by a number of connections, making its way back to the battery voltage when the power is ON. There should be a steady battery voltage at that connector. If it fluctuated or becomes intermittent, then the alternator output will also fluctuate.

Time to go troubleshooting!

P.

 

It is fairly common for the connector on the back of the dash to get hot because of a loose connection. That causes the solder connections to crystalize and go bad. Here's info on how to fix dashboard problems:

http://www.batee.com/corvette/dcrg/repair/