2001 GMC Truck headlamp trouble.

2001 GMC TRUCK
60,000 MILES • AUTOMATIC
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YUNMI LEE
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  • 1 POST
GMC T8500(2001)
headlamp Lo switch on...... High On(A little bright) + Low On(very bright)

headlamp Hi switch on...... High On(very bright) + Low On(A little bright)

high dimmer (normally)

Selection switch, the brightness varies only.
Low switch On: High lamp Off <------I think that this is normal.
I can not help anyone.
I need an electrical circuit diagram.
I will waiting for your advice.


Jul 22, 2014 at 8:10 AM
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HMAC300
  • ✓ASE Certified Mechanic
  • 48,601 POSTS
  • ASE Certified Mechanic
if this is a medium duty truck we have no diagrams for that. however check underhood fuse box for fuses and relays as well as grounds to headlights
Jul 22, 2014 at 9:31 AM
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