flickering dash

[8cam]

I've noticed recently that at idle with my lights on, sometimes I'll get a slight flicker in the dash lights that goes away the second I bring the revs up even a little. No warning lights, battery is fully charged and everything works perfectly. Do you think this is a sign of a failing voltage regulator, or is the alternator on the way out?

[Billy Mild]

I have the same issue. It seems to happen more often when I have the A/C on. I just cleaned the main battery terminals last night. So I don't know if that made a difference or not.

I did clean all the grounds inside the cabin. This seems to have fixed my random ABS warning light.

[csavaglio]

My LT4 car does the same thing and I even get a split second drop on the voltage gauge when it happens. Seems like it does it more often when it's cold and more often when there's more load, like lights, AC, etc. I put on a new alternator, new battery, new battery terminals, made sure everything was tight, etc. There was never any corrosion on the cables or anything. The voltage reg is integrated on the alternator, so that's new too.

My feeling is that maybe it's the headlight switch, but it doesn't seem to be bothering anything other than being a nuisance, so after a couple of goes at trouble shooting, I gave up. The car still remains super reliable.....

My ZR-1 doesn't do it at all and none of the other 8 or 9 C4's I've owned have done it.

Chris

[Roadster]

I also have the same problem on the 94, but goes away as Mark mentioned.
Still it is noticeable, but doesn't effect how the Z runs or drives, which is a good thing.
Depending on the alternator, if I remember correctly, the stator has to be "excited" in order to maintain the proper voltage, and this does not happen until the engine reaches or is revved to a certain rpm. (usually around 1500 r's)
This was also prevalent on my 82, I would just make sure I brought the r's up, although the dash lights weren't flickering, the volts weren't where they were supposed to be.
IMO, if the flickering goes away after a few seconds and doesn't happen when your driving, I wouldn't worry about it. Just make sure, even with a "cold" engine you bring the r's up to 1500 and you shouldn't have any problem.
On the other hand, if it continues when driving at different speeds, then there is something that isn't right, which could be the brink of something "big", (like getting stuck on the highway) or something real "small", such as a short, possible wire break, etc., etc, which could turn into something "big", if you never check it out!!!.......

[ZR1North]

I had that issue as well. It disappeared completely when I replaced the five-year old battery.

I keep a tender on the battery if the car is going to sit for a couple of weeks. With the unit I replaced, I noticed the green (fully charged) light would be illuminated on the tender, but the battery was too weak to crank the engine. Replacing the battery addressed that issue and the flickering dash lights too.

[Schrade]

I'm betting it's grounds integrated into the display module in the dash.

I cleaned and di-electric greased ALL my engine bay ground straps when doing top end cleanup, and the flicker persisted.

I think the CCM ground connections are on the back of the block - are they not???

[csavaglio]

My LT4 has been doing it for the year and a half I've owned it and it doesn't seem to have gotten worse.....also doesn't seem to affect much except the occasional flicker. I daily drive it and I've put about 15k miles on it. The dash grounds sound like a possibility.

I can't remember if I put a new battery in it or not when I first got it....I guess I could go out and pop the hood to check. I shipped all the other cars up to Colorado already.....

[Roadster]

I had that issue as well. It disappeared completely when I replaced the five-year old battery.

I keep a tender on the battery if the car is going to sit for a couple of weeks. With the unit I replaced, I noticed the green (fully charged) light would be illuminated on the tender, but the battery was too weak to crank the engine. Replacing the battery addressed that issue and the flickering dash lights too.

My battery is from NAPA installed by a PO in 2012, and as soon as I rev the engine, it is gone. But checking all grounds is always a good thing.

[csavaglio]

Ok, the battery on my 96 was about 4 years old....long before I got the car.... and led a rough life....we had to jump it when I went to pick the car up and the car had spent a good portion of its life sitting. I put a new alternator and it was fine from then on.

I just put a new battery in since I'm moving where it's cold and it's good peace of mind. We'll see if it helps and I'll report back.

Chris

[Schrade]

Ok, the battery on my 96 was about 4 years old....long before I got the car.... and led a rough life....we had to jump it when I went to pick the car up and the car had spent a good portion of its life sitting. I put a new alternator and it was fine from then on.

I just put a new battery in since I'm moving where it's cold and it's good peace of mind. We'll see if it helps and I'll report back.

Chris

http://freesmileyface.net/smiley/food/eating-popcorn-04.gif

Got a new battery about to go in too - see if it makes a difference here...................................

[csavaglio]

Well, a couple days and about 150 miles and I haven't seen the flicker. I don't want to jinx it, but it seems like the battery did it. I'm surprised, because it never didn't have any other issues.....it always started fine and everything.

Chris

[Fully Vetted]

Mine did it until I replaced my battery about a month ago.

[Schrade]

New battery fixes dash flicker.

Sounds good to me; but I'd sure like to know how THAT works :confused:

Any electronics gurus here, can 'splain it??? Given ALL grounds are correct.......

Gotta' have somethin' to do with pulse width modulation?

[Billy Mild]

New battery fixes dash flicker.

Sounds good to me; but I'd sure like to know how THAT works :confused:

Any electronics gurus here, can 'splain it??? Given ALL grounds are correct.......

Gotta' have somethin' to do with pulse width modulation?

Take the battery terminals off and spray them liberally with some battery cleaner. Then spray some of the battery cleaner in the bolt hole. That should give you a nice clean connection.

[batchman]

I have found that when I get dash flickering (remembering I use a battery 1/4 the size of most) if I jiggle the "dimmer" it stabilizes, seems like a noisy pot in a circuit sensitive to signal to noise ie lower signal (battery V) same noise = higher ratio (maybe it is PWM). Moving the pot reduces the noise.

HTH,
- Jeff

[csavaglio]

Well, guys, I just made the move from Las Cruces to Colorado Springs....about 550 miles...in the LT4. The first half was in pouring rain with the lights on. No flicker.....

I'm gonna pronounce the flicker fixed.

Great suggestion on the battery. I've had previous cars do weird things when the headlight switches get iffy too, which I why it was my first thought after checking all the cable connections.

If I were the OP, I'd give the battery a shot. Worst case is it's good peace of mind having a fresh one in the car.

Chris

[Franke]

Well, guys, I just made the move from Las Cruces to Colorado Springs....about 550 miles...in the LT4. The first half was in pouring rain with the lights on. No flicker.....

I'm gonna pronounce the flicker fixed.

Great suggestion on the battery. I've had previous cars do weird things when the headlight switches get iffy too, which I why it was my first thought after checking all the cable connections.

If I were the OP, I'd give the battery a shot. Worst case is it's good peace of mind having a fresh one in the car.

Chris

Welcome back to Colorado O'wise one! :)

[8cam]

I know I replied to this thread, but apparently it flew into the ether somewhere. My battery is about 18 months old and since I drive the car almost every day, it should be in good shape. I'll check it with a real meter this afternoon. The only time I notice this flicker is at idle, usually when the a/c is running but I have seen it with the a/c off too. I've had voltage regulators fail before, but those really show symptoms when running. I wasn't sure if this flicker might be an early sign.

I have noticed that my a/c compressor creates a LOT of load on the engine, and it does make some noise. For such a big powerful engine, I wouldn't think the compressor would cause much of an impact. But it's definitely noticable - the engine is nowhere near as lively with the a/c on. So my other thought was compressor bearings on the way out, creating too much drag on the engine.

[Roadster]

I know I replied to this thread, but apparently it flew into the ether somewhere. My battery is about 18 months old and since I drive the car almost every day, it should be in good shape. I'll check it with a real meter this afternoon. The only time I notice this flicker is at idle, usually when the a/c is running but I have seen it with the a/c off too. I've had voltage regulators fail before, but those really show symptoms when running. I wasn't sure if this flicker might be an early sign.

I have noticed that my a/c compressor creates a LOT of load on the engine, and it does make some noise. For such a big powerful engine, I wouldn't think the compressor would cause much of an impact. But it's definitely noticable - the engine is nowhere near as lively with the a/c on. So my other thought was compressor bearings on the way out, creating too much drag on the engine.


We just got back from a 300 mile trip from Gettysburg with the ZR-1 and the flicker is still there slightly but once I am moving, it goes away, and doesn't seem to return. The A/C works great and my engine runs just as good with the A/C on or off, I haven't notice a difference in power or performance either way. It just gets up and goes when needed......:-D