A little help please.

[BigEasy]

Hey guys, gotta question I tried several searches and came up with nothing.

 

2005 GMC Seirra Z71. 19k on the odometer.

 

This truck is on its way back to the dealer for the second time for this.

 

The problem.

 

After the truck warms up to operating temp( I don't know if this has anthing to do with it but, it's just when I notice it. after driving about 10 minutes)

 

When I go to accelerate, say, merging into traffic on the interstate and I have to accelerate fairly quick. Not a "pedal to the metal" move but, just a good quick acceleration (say from 40 to 70 mph) my headlights, dash lights and interior dome/map lights if I turn them on "Pulsate" to the point that it is very noticable and people have even moved to the shoulder of the road like I'm trying to get them to pull over. It does it on low and high beams and almost exclusively when accelerating. Sometimes i'll notice it at a steady speed.

 

First time at the dealership the service writer told me that the Battery and Alternator checked out fine and that it was normal I said "No way you'll convince me that is normal" She prceeds to tell me that there is a TSB stating such and that she would fax me a copy (which I have not seen, by the way, even after repeated calls)

 

is there anything that any of you guys think may be the culprit? On top of being anoying, it's dangerous. there is no telling what on coming traffic thinks as they meet me. It aint funny but I almost gotta laugh

[GM-Tech]

Sure doesn't sound normal to me. And I'm not aware of any TSB that says any such thing.

 

These things use a battery/generator control module nowadays. The generator is turned off when it's not needed, such as when crusing down the highway. You'll find this module clamped around your negative battery cable.

 

It could be that the generator is being turned on and off rapidly, which would not be normal. That's just a wild guess, mind you.

[BigEasy]

Good deal GM.

 

I'll politely suggest that they check the GCM when they call today. Really what needs to happen is they need to keep it overnight and let one of the tech's drive it home and drive it around tonight. Whether they will do that or not is another story