Hello everyone. I have a 2008 H3 Alpha that when i start the truck the lights pulse interior and exterior. I had the alternator tested and that was ok. I replaced the battery and still same issue. I cleaned all the battery terminals to make sure the connection is good. This just started happening recently. I am wondering if its a bad ground wire. Do you know where the ground is located on a 2008 H3?

 

What's the battery voltage at startup?

 

FYI, startup voltage should be +15v!
After you verify voltage, Check:

 

About 15V, I also remove alarm system cpu to see but no different.

 

 

Here is a vid of the headlights blinking

 

Here is what I found. When I start the truck the battery voltage is about 15.2 then it dropped to 14.4. After a while I did the same test and at start battery is at 14.6 never 15 could it be the alternator? I did pull the negative off the battery while car was on and it ran for a few min then I shut off.

 

Not the alternator, The GM regulated voltage control system(GBCM) can vary from 11.5 –15.5 volts.
Notice any difference when you rotate the HL switch?

 

Are you still using the crappy azzed OEM Battery Terminal Connectors??????????? If so, hack them off and replace with a quality aftermarket set like Stingers or your favorite brand. First mod to be done to every H3/H3T.

 

i am using stock terminals but they are clean. I also check the HL switch and no difference. Also If the engine is not running the lights don't pulse.