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Axle · 12-31-2022, 09:39 AM

Thermal overload in the headlight switch probably.
Do your lights a favor and wire up an external relay harness for your headlights, might as well get the most out of those H4's.

12-31-2022, 09:39 AM	#4
Axle Registered User Join Date: Jul 2011 Location: SW Ontario Posts: 1,221	Re: where is the headlight relay on a 1977 gmc 3500 Thermal overload in the headlight switch probably. Do your lights a favor and wire up an external relay harness for your headlights, might as well get the most out of those H4's.