2004 Chevy Silverado Dimming Dash Lights

UOFMSILVER

MEMBER
2004 CHEVROLET SILVERADO
V8
2WD
AUTOMATIC
52,000 MILES

If accelerating hard, my dash lights dim, and I seem to have a lag in power. I believe all other lights dim too, but I don't know for sure. This happens as the transmission is getting ready to shift. I really notice it when passing and if merging into fast traffic on highways, or if I just want to have a little fun. This does not happen if I accelerate slowly (normal?).
Alternator has been replaced, the "Big 3" have been upgraded to 2 guage wire, stock battery tested good, serpentine belt (main) has been changed twice, along with the belt tensioner. The remaining pulleys have been checked for grease or dirt.
I have tested with all accessories off, and with most on. The same problem always occurs. And I don't have my tunes blasting when going down the road.
It will always do this between 1st and 2nd, and 2nd and 3rd gears, but I have never noticed when shifting from 3rd to 4th.
It doesn't matter if the engine is hot or cold. I can drive it for 5 hours and it will still do it when I "punch" it.
I have even taken to a dealer - they can replicate the problem but can't fix or tell me why it's happening (I should probably go to a different dealer).
I am worried that I will get plastered on the road when merging onto a highway or passing someone.
Any help is appreciated.

2 Replies

BUDDYCRAIGG

MECHANIC
2,262 POSTS

It sounds like you have done everything on the Positive side of the circuit that you can.

Now how about the ground side.
It's a stretch, but lets say you have some poor body grounds at the cables and the frame and body are getting their ground through engine mounts or something.

And when the engine is under load and the torque is rotating the engine over, you are loosing some of your ground.

Perhaps add some additional wires between the engine and the body and or frame.

Good luck