Help about headlights an ac

Asked by GuruLSL2M Apr 09, 2019 at 09:45 AM about the 2004 GMC Envoy XL SLE 4WD

Question type: Maintenance & Repair

I need help trying to figure out what's wrong with my
headlights they work fine on bright  an only work when they
want to on regular an for my ac heater an defroster I can
only run them without using the circulating an the frost
button if I turn the 2 on my car will die out

1 Answer

26,640

Note the diagram for headlamp. I'm talking about manual headlamps, not automatic. With intermittent issues need to do testing when problem is ongoing, voltage and ground, you can use test light to check. Any applicable trouble codes? I did see some headlamp trouble codes. These were B type codes, to check codes, at the least, you need an obd2 code reader that will work with your vehicle and read manufacturer specific codes. The headlamp switch and dimmer grounds a circuit from the bcm, letting the bcm know what your doing with head lamps. The bcm controls the hdm relay. The problem could be almost anywhere for that system? Any codes and your testing may narrow down the problem. Hopefully

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