I have an 84 T/A the engine was redone about three years ago. Runs great no issues at all. We don't have any emissions hooked up and haven't for a long time. The engine now has a vacuum distributor instead of electric. We also have a full electronic dash now. Here's what's happening.

I hope someone can help. Never had this happen. has been running great until after we drove to a cruise in the other night. It started with the speedometer board and dash monitors randomly shutting off and back on. Then it went to the entire dash flashing off and then the car just dying while we were driving. No signs that the car was going to die. The dash went out and car died. No headlights, flashers, or anything. Then after about a minute the interior lights would work, then another minute the headlights, and after several minutes the car would start again. We'd drive a little and it would do it again. We'd pull off and let the car sit for a little while and back on. Then it got worse. The dash started to flicker and lights flashing on them, they'd get dim and only half way light up with some not coming on, and the car would start to loose power. It would all go out then car die again.
We have checked the battery connection as wires and can't find anything loose or bad.

Anyone have anything like this happen to them? Very nerve recking trying to make it home. The engine runs fine but one when the dash starting going haywire, the engine started to act a little strange and hesitate but once the dash stopped going crazy it was back to acting fine. Long trip home.

 

Get your alternator tested or check the voltage yourself at the battery when it starts acting up. Get a voltmeter from wal-mart. One of the best investments you'll ever make.

Steve

 

Exactly what I was going to suggest.

 

Check ALL of your grounds inside and outside of your car.
also check positive wire to starter.

 

For grounds you should have 3 major underhood grounds:

1) neg batt cable to block
2) groundstrap from pass head rear to firewall
3) smaller wire from batt neg to fender

 

thanks guys. I'll look into the other grounds and check them out tomorrow. hopefully it is one of those.

 

Also grounds from the back of the drivers side heads. At least on my car. Make sure all the ground wires are tight where they attach and you cannot wiggle them.

 

Might have grounds from the rear of both heads. Many GMs do.

 

Checked all grounds and they are all tight and clean. No issues with them. Checked on the starter ground as well.I'm starting to lean towards ignition switch maybe.

 

The ignition switch is possible but heat related failure of a switch or even wiring connections is less common then something like a voltage regulator. In fact, when I tried to modify my C130 alternator to produce 130amps, it caused my car to do exactly what yours seems to be doing. It was worse when I ran my sound system, vent fan, and lights all together at night. The regulator was overheating and shutting down the alternator. After a rest, it would cool down and work for a while until it heated up and shut down again. I installed a higher output alternator and solved the problem.

 

thanks for the info on that. We are running a lot of electronics on the car now. Maybe our issue as well.

 

Yeah. My problems started when I added 480 watt Hella headlamps, and 2,300watts worth of sound system. I'd turn on the headlamps and stereo and watch the volt gauge drop. Tried the 130watt upgrade on the alternator and an Optima yellow top, that's when the alternator started overheating. Finally, went with the Powermaster 230 amp alternator, bolts right in with a small modification of the stock bracket, and the Optima yellow top. (Be sure to install a 6 gauge charge wire directly from the alt output to batt+ or you'll blow the fuse link in the OE wiring) I have no electrical system issues now.

 

A bad ECM can cause this also.

 

The ECM has absolutely nothing to do with the dash lights or the alternator. The ECM is often blamed and rarely the cause of drivability or electrical issues.

 

o.k. here's my update on this thing. I checked every ground wire on the car and they are great. Nice and tight and clean. cleaned the battery cables just in case, had battery and alternator tested and was told they were good, checked for loose wires or any wires that were melted and no issues. no blown fuses or relays that are hot. I replaced the ignition switch ( never again...that was a nightmare)
I thought it was fixed. drove it for about an hour around town and no issues at all. I take the car out about once a week. took it today and did fine until i was coming home after about ten minutes. the dash lights all flickered off. I get in the driveway and shut the car of. then turned it back on and it was fine. I had the door opened and shut it off then tried to turn it back on and nothing.
I could turn the key and no sound and no dash lights but the interior lights work and the radio would flicker on/ off real quick. I could turn to the acc mode and only have radio but still no lights on the dash. Now my dash is switched to all digital gauges. We also have a separate power so we can turn just the dash on at car shows. I could turn the power on for that and the dash will come on but when i turn the key there is no power to start or for the dash lights to come on. After about ten minutes the power was back to start the car. Again, the car had power for everything else including all lights but not to the ignition.
Not happy with this gremlin that has come about.

 

I had a similar problem with my 87 trans-am, kept popping the dash light fuse then the car would die. I didnt know that the alternator runs through your digital dash to charge your battery. So if your dash is out for long enough your battery will go dead.

 

Maybe your printed circuit is fried behind your digital dash.

 

a couple of things to check, the fuse links at the starter may be going bad. usually tugging on them will revel if they are bad.
the bulkhead connector on the firewall where the underhood harness connects to the in-car harness. with the car idling in park and the parking brake on, wiggle the wiring at the bulkhead connector. if it acts up, unbolt the connector and check for problems. the bulkhead connector has a tar like substance in it, so it can be messy and hard to see any problems with it.

 

thanks, I'll check into those.

 

tried to replicate the issue with no luck. Ran the car for about 30 minutes, turned everything off and on, pulled panels and wiggled wires around on everything I could find, even on the starter as it was running, moved it in the driveway but to no avail. It seems very random when it wants to do this issue. I thought maybe heat but it is very hot outside and I ran the car with it constantly having the fan come on to cool it off and no luck causing it to do the same issue.