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Ask 17 years GM tech Your Own Question
17 years GM tech
17 years GM tech, GM Master tech
Category: Buick
Satisfied Customers: 1918
Experience:  25 years automotive experience, 15 years with Saturn
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2002 buick regal: quit working..work fine..fine fuses and bulbs check

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2002 buick regal low beam headlights quit working ...Hi beams work fine fuses and bulbs check out ok.....Is it BCM?I forgot to include headlights would go off sometimes on there own and then come on a few minutes later......

17 years GM tech :

Hello and thank you for your post. I am a master certified GM tech and can help you to resolve your issue. do you have a 12V test light or a volt ohm meter?

Customer :

Yes I do

17 years GM tech :

OK. You will need some pinpoint test ideas...first, go to the bulbs and test for 12V and ground at the headlamp bulb and tell me which is missing. Check them both. let me knwo and we will go from there.

17 years GM tech :

I will be avail for about 20 more minutes, then on and off the rest of the day.

17 years GM tech :

are you there?

17 years GM tech :

OK i will switch out to q & A format.

Customer :

I will have to do this later I am going to work .....

17 years GM tech :

OK. get back when you know what is missing.

17 years GM tech :

I need the 8Th digit in the vin ...a 1 or a K in case something is different

i await your response

 

Customer: replied 6 years ago.

Ok I have 13.8 volts at headlight and no continuity at ground.....8th digit of VIN is K

 

I also have no symptoms of bad BCM @ least I think...

 

 

Is there a headlight relay for lowbeams? could that be bad?

looking at the headlamp circuit, the headlamp dimmer switch applies ground to whichever you select...lo or hi beams.
If the dimmer goes bad then you can lose ground to one or the other. The bcm and headlamp switch would affect both.
Go to the dimmer switch (the highbeam stalk)
the yellow is ground in and tan is ground out to low beams
With the headlamps switched on and low beams selected,both wires should have ground. If only the yellow has ground then the dimmer switch is bad. If both have ground,the problem may be the underhood fuse block because the ground wire passes through the fuse block and splits between the left and right headlamp in there.
It could also be a loose wire at either place so you need to start wiggling wires as well to see if the lights flicker.
I can't access connector views for the fuse block wiring until monday...so if you can check the switch first that will be a good place to start.
I will attach the wire diagram for you also.

here is the diagram
17 years GM tech and 3 other Buick Specialists are ready to help you