when i have my heater is on and i turn on my head lights the heater blows weak and my passanger headlight is dim. why??? when head lights are off the heater is fine when heats off the lights are fine??? anyone know whats going on. but the car runs and every thing else is great but the lights and heater.

 

Alternator might be going out...

 

I would also vote for your alternator

 

yeah change your alternator, had the same prob here

 

really how does that work??? i dont understand how that effects the lights???? i guess thats why my starter works at will. lol some times it works 1st try some times it takes a few trys.

 

It could also be a bad ground somewhere.. I just replaced my alternator maybe 10k ago and my lights were still dimming at idle when the fan was on. I recently relocated my battery to the trunk and have 2 gauge for the battery ground, upgraded the 8 gauge tranny ground to 6 gauge, and have 8 gauge for the valve cover ground. No more lights dimming for me now. Although I still think my rebuilt alternator isn't at it's full potential.

 

ok i already re did the ground with 8g wire. the tranny and the othe ground only one i did not do was the one on the valve cover.

 

Well then 99% chance it's your alternator, the valve cover ground is close to useless

 

thanks to every one for the help. a will let you know if that takes care of the problem. any one got any da parts????.