Hello everyone! I need help. Stumped on a problem.

[jczernicki]

Hello everyone. I am new to the site. I have done some checking on this site but never joined. I am perplexed with a problem and have had multiple people try and help. I am trying to avoid a huge expense having to take it to a dealer. I am an electrician by trade so as you will read my problem frustrates me........

 

I have a 2008 GMC Sierra Denali 1500. I love the truck. Had it since new and now have 120,000 miles on it.

I have recently developed a problem with my headlights, tail lights, interior lights, every illuminated thing on/in the truck except for the radio is flickering. Its intermittent. Sometimes its very noticeable and sometimes not so much and sometimes not at all. It seems to be in time with the engine RPM's.

 

I have replaced the original alternator with a remanufactured one from Auto Zone. 160 amp.

I have cleaned battery connections and tightened. Battery is a couple years old.

I checked the 2 wires coming off negative battery terminal to frame. Removed and cleaned the ground connections on the frame.

I replaced the battery current sensor clamped around the positive wire coming off the battery.

Today I replaced the headlight/fog light/dome light cluster switch in dash.

 

Still have the same problem. I have done a lot of research and found a bunch of good tips and as you can see I've been trying with no success. Help please???? I welcome any expertise or past experience on this.

 

Jim

 

 

[justin.flev01]

Could be a problem with your BCM

 

 

Sent from my iPhone using Tapatalk

[jczernicki]

Well This morning it really is showing itself. We are having a blizzard here in the Northeast and on my way to work this morning is the worst I've seen it. My headlights go from being nice and bright to dim. When it dims I notice the voltage gauge on the console going from 14+ volts down to 12. Then the lights come back bright and the voltage gauge climbs back up. They are very noticeably flickering.

 

Could the BCM cause this?

It acts exactly like a bad alternator.

 

Now I'm at work with it and hoping I can get it home through the crazy snow. :-(

 

 

 

[Coby7]

Did you check the ground on the firewall, it's usually the one that affects the lights. It has a tendency to come loose because of constant movement.

[BigBadSierra]

Did you check the ground on the firewall, it's usually the one that affects the lights. It has a tendency to come loose because of constant movement.

 

This is my first thought as well.

 

Sound like a loose or corroded grounding point.