Check gauges light randomly flickers
Thread Starter
Joined: Jan 2002
Posts: 4,069
Likes: 74
From: Casselberry FL
Check gauges light randomly flickers About a week after I got my '98 Camaro back from the shop for a cam sensor replacement, the check engine gauges light has started flickering and fading in and out. Not a steady repeating blinking like with a misfire. It can be on somewhat solid, and while driving and idling the flickering pattern will change. Poor ground? something else?
Last edited by JimMueller; Jul 24, 2025 at 01:45 PM.
First off I'd check for codes. If you have a code, then it is supposed to just be solid on, and it is possible the bulb (or LED, I forget which it is) is loose and/or going bad, causing it to flicker.
If you have no codes then start digging into wiring issues.
If you have no codes then start digging into wiring issues.
Thread Starter
Joined: Jan 2002
Posts: 4,069
Likes: 74
From: Casselberry FL
Voltmeter gauge looks normal, not in the red, steady around 12'o'clock position. I haven't scanned the PCM voltage or performed a charging system check, but I'm taking it into the shop tomorrow AM. I swear they commented to me they found something unusual with the alternator wiring and had to make changes, but it's not on the invoice or text messages.
I do have this Mechman alternator, maybe they messed up this custom blue/green/yellow harness.
250 Amp Elite Series Cast Alternator for GM Truck - Mechman Alternators
They also found corrosion inside the OEM engine harness, and I'm not finding a way to buy new or rebuild it, any ideas without swapping to '99+ PCM?
I do have this Mechman alternator, maybe they messed up this custom blue/green/yellow harness.
250 Amp Elite Series Cast Alternator for GM Truck - Mechman Alternators
They also found corrosion inside the OEM engine harness, and I'm not finding a way to buy new or rebuild it, any ideas without swapping to '99+ PCM?
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From: Schiller Park, ILL Member: #317
Only time I've ever had a "flickering" check gauges light is when voltage was dipping just barely into the red (and that was a wiring issue in my case). But my voltmeter confirmed this, so there was no question as to the source.
Does oil pressure also look good and steady?
What do you mean by "corrosion inside the OEM engine harness"? What is meant by "inside"? Are you referring to the actual pins where the PCM connects to the harness? There is a gasket there, and I seem to recall reading somewhere that this gasket is supposed to be changed any time that the PCM harness is disconnected (not sure how many folks actually do that, but I recall it being recommended somewhere in the service manual - if this wasn't done, and this is where the corrosion is, then it might explain why there is corrosion).
But either way, if there is corrosion at various vital connection points and/or marginal wiring/connectors, etc., then I would certainly start there in terms of any electrical diagnostics.
Does oil pressure also look good and steady?
But either way, if there is corrosion at various vital connection points and/or marginal wiring/connectors, etc., then I would certainly start there in terms of any electrical diagnostics.
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From: Schiller Park, ILL Member: #317
What happened to initially compromise the insulation (i.e. why was it being repaired in the first place)? Was there an event with rodents, or did something partially melt from a short or contact with exhaust, etc.? Was the car in a flood event?
Just trying to figure out how deep the issue might run. If it's just one wire or one area, I don't think you need a whole new engine harness.
Just trying to figure out how deep the issue might run. If it's just one wire or one area, I don't think you need a whole new engine harness.
Thread Starter
Joined: Jan 2002
Posts: 4,069
Likes: 74
From: Casselberry FL
It's never been flooded... once in a while I'm forced to drive in heavy rain. Hydralocked the original engine in roughly 2000. The car spends most of its life outdoors. No known rodent issues. Had a fire ant infestation years ago. A couple symptoms happened about the same time early this year... brake master coupling broke, emptying reservoir. But after the repair it still ran rougher than normal. A few days later it seemed down on power, thought it was related to recent brake repair. Had noise in the B2 valve train, found a loose rocker arm & broken aftermarket rocker arm bolt. I found both ends of the bolt in the top of the head and repaired that. Still won't run so I tow it back. They find a few different things... broken cam position sensor, damaged knock sensor connectors due to header heat, 'stretched' Hinson C7 timing chain, shorts in the #4/#5/#8 injector/ignition harness, etc. While putting the car back together they stumbled across the harness concern.
Thread Starter
Joined: Jan 2002
Posts: 4,069
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From: Casselberry FL
The shop could duplicate the check gauges issue but couldn't locate any wiring faults in the engine bay, and alternator is connected per diagram. I do have all LED bulbs behind the dash, I guess I can try swapping the bulb in that area. Will also review Helms manual. They did ask a couple questions whose answers escaped me whether are normal behavior.
1) OP gauge, when engine stopped and key immediately to off, gauge doesn't drop to zero, key on/off again psi goes to 0.
2) fuel level drops a little (1/8-1/4) on key off, goes back up on key on.
1) OP gauge, when engine stopped and key immediately to off, gauge doesn't drop to zero, key on/off again psi goes to 0.
2) fuel level drops a little (1/8-1/4) on key off, goes back up on key on.
Joined: Nov 2001
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From: Schiller Park, ILL Member: #317
The insulation must've been compromised somehow, perhaps by heat, but it stands to reason that other wires in the area might be compromised too (especially since you mentioned shorts in the injector & ignition harness). Still though, it's a big job to re-wire the whole engine bay. Not sure if that's needed if everything is working now other than a flickering check gauges light (perhaps it does have to do with the LED cluster bulb(s)?
This is exactly how the gauges in my stock, very low mile (19K) '98 Z28 have always behaved. The only gauges that zero out on immediate "key off" is the voltmeter and tach. Fuel gauge drifts down just a bit as you described, and the OP gauge actually drifts up just a touch usually.
This is exactly how the gauges in my stock, very low mile (19K) '98 Z28 have always behaved. The only gauges that zero out on immediate "key off" is the voltmeter and tach. Fuel gauge drifts down just a bit as you described, and the OP gauge actually drifts up just a touch usually.
Teching In
Joined: Sep 2016
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From: Camp lejeune NC
About a week after I got my '98 Camaro back from the shop for a cam sensor replacement, the check engine gauges light has started flickering and fading in and out. Not a steady repeating blinking like with a misfire. It can be on somewhat solid, and while driving and idling the flickering pattern will change. Poor ground? something else?