I bet i'll get ya on this one...

[mixtapesyndicate]

97 Tahoe 4wd 5.7 vortec.

The headlights and dashlights are pulsing while in drive. When put in part it either stops or goes to a state that I can't notice it. I have a big 3 upgrade in place.

I know most of you will be thinking alternator, that was my first thought too. Took it up to autozone and had them put their meters on it. tested out fine both in park and in drive.


Any other ideas or have you had something similar happen?

 

[haks310]

It's the alternator, voltage regulator is spiking.

 

[blackcoffee]

Freaky. Don't drive it tell you get it fixed.

 

[mixtapesyndicate]

It's the alternator, voltage regulator is spiking.

Thats what I thought, but when it was hooked up the the meters everything check out fine. Still think that could be the issue? I'm sure its the original alternator (over 200K miles) so I guess I wouldnt be surprised.

 

[2yukons]

My friend was having similar issues with his car. Got the alternator checked out and was told that it was fine but he was still having the same issues. He ended up replacing the alternator and all the problems went away.

 

[Grebbler]

Their meters may not have a quick enough sampling rate (if digital) or sensitivity.

Also, the battery will act as a filter further tricking the meter. Unfortunately, the spikes could be quite high and the battery can only take so much abuse before failing.

If the battery, which is absorbing the spikes, should fail or become disconnected while the engine is running - the spikes will fry the on-board computers and whatever else is on at the time.

It ain't pretty.

 

[haks310]

Thats what I thought, but when it was hooked up the the meters everything check out fine. Still think that could be the issue? I'm sure its the original alternator (over 200K miles) so I guess I wouldnt be surprised.

Yes sir.

Meters wont pick up the spikes. If you want to test it yourself pick up an analog voltage gauge and hook it up to the alternator. You will see the needle spike while driving.

 

[mixtapesyndicate]

Well, I guess we are all in agreement. Its going to be an alternator. Would you guys suggest upgrading to a high output alternator? If so where would you suggest i get it and how big of an alternator would you suggest?

 

[MUDDER TRUCKER]

ok before u get a alternator check your ground from batt to fender well or body, this happend to me, that ground will make your dash and inter lights do that , the bolt holding the wire in place was loose.i tested my alt, it was good too. try that.

 

[mixtapesyndicate]

Heres a few pictures of the engine compartment and mostly charging system. Also a close up picture of the batt ground to chassis.