Dimming Dash & Headlights and more....HELP
Thread Starter
Le Mans Master
Joined: Dec 2005
Posts: 8,524
Likes: 914
From: Communist Colorado
Dimming Dash & Headlights and more....HELP
Ok, this is on a 95 6 speed, 55k miles. The other day my son noticed his headlights and dash lights dimming. I figured the alternator was about finished. Well, his voltage key on engine off is 12.6 volts. Running is between 13.8 & 14.3 That all seems normal to me.
Now the next part is really got me baffled. He said he experienced the engine stunbling really badly and it stalled. Started it up, ran fine for an hour or so & the same thing happened again.
Hes a Marine and out in the field for training for the next two weeks. Can someone help us out? Im in Colorado, hes in 29 Palms
Battery cables are tight
12 volt wire on the back of alt tight
Belt is good
Now the next part is really got me baffled. He said he experienced the engine stunbling really badly and it stalled. Started it up, ran fine for an hour or so & the same thing happened again.
Hes a Marine and out in the field for training for the next two weeks. Can someone help us out? Im in Colorado, hes in 29 Palms
Battery cables are tight
12 volt wire on the back of alt tight
Belt is good
Thread Starter
Le Mans Master
Joined: Dec 2005
Posts: 8,524
Likes: 914
From: Communist Colorado
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
The key here is that the voltmeter was used when the lights and engine were normal. My money is on low system voltage when the lights dim (the only cause if they come back to normal) and the engine stumbles. Look at the dash voltmeter when these symptoms occur, I am sure you will see low voltage. Finding the cause is difficult if the condition won't continue while you make more measurements to see if the alternator output quits (my money is on it quitting) or if there is significant voltage between the battery negative terminal and car frame (poor ground connection, should be less than 0.3 v), or significant voltage between the battery positive terminal and after the ignition switch (a good place to test is the center pin on the cigarette lighter, less than 0.4v). Intermittents are very hard to find and much easier to find if you are making measurements when they occur.
Last edited by jfb; May 5, 2010 at 11:23 PM.
Pro
Joined: May 2006
Posts: 637
Likes: 0
Well, I guess I´ll join the club with a 91 with the same symptoms.
Fairly new alternator (got a new one along with a new battery for about 3.5 years ago).
And it´s pretty much a W(eekly) D.
I´m wondering if the coil in the distributor could cause these weirdo´s, since I have never changed it and put 20K miles on it since I bought it.
I don´t think the prev. owner changed it either, changed the cap and rotor once and it didn´t look that nice in there.
I also have an occasional high rpm miss, but that is probably a module on it´s way out.
I will do some troubleshooting when I get home (have the FSM).
Sorry to jump in between, but I was just thinking about the coil might having to do something with it...
Maybe yours as well even though an LT1.
She´s at 75K miles now.
Fairly new alternator (got a new one along with a new battery for about 3.5 years ago).
And it´s pretty much a W(eekly) D.
I´m wondering if the coil in the distributor could cause these weirdo´s, since I have never changed it and put 20K miles on it since I bought it.
I don´t think the prev. owner changed it either, changed the cap and rotor once and it didn´t look that nice in there.
I also have an occasional high rpm miss, but that is probably a module on it´s way out.
I will do some troubleshooting when I get home (have the FSM).
Sorry to jump in between, but I was just thinking about the coil might having to do something with it...
Maybe yours as well even though an LT1.
She´s at 75K miles now.
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Burning Brakes
Joined: May 2010
Posts: 1,167
Likes: 2
From: Pittsburgh Pa
Definitely sounds like an alternator issue...bad brushes, bad diode or voltage regulator inside.
The pulsating issue above was definitely an alternator issue from my experience. Kind of strange the battery was the fix. That's a first. I've fixed quite a few cars with the pulsating and it was always the alternator....hm....weird.
Well, to fit in, I too am having voltage problems this week. I think my alternator is definitely takin a dump. Sporatic battery light, voltage drops here and there, dimming, etc. Must be a bad week for alternators. Figured I'd take a look in here in case there were any common Vette spook issues that present as a bad alternator.
The pulsating issue above was definitely an alternator issue from my experience. Kind of strange the battery was the fix. That's a first. I've fixed quite a few cars with the pulsating and it was always the alternator....hm....weird.
Well, to fit in, I too am having voltage problems this week. I think my alternator is definitely takin a dump. Sporatic battery light, voltage drops here and there, dimming, etc. Must be a bad week for alternators. Figured I'd take a look in here in case there were any common Vette spook issues that present as a bad alternator.
Instructor
Joined: Feb 2006
Posts: 176
Likes: 0
From: Pasadena MD
I have a 92 with the same problem my stumbling will go away if i turn the traction control off the lights i have not looked in to fixing yet but i think its a ground issue the weirs in these cars where not made to last.
