This article will help you to test a BAD headlight switch in step-by-step manner. Specifically, you'll be able to troubleshoot a ‘no head lights’ or a ‘no park lights’ problem to the head light switch.
Testing the headlight switch (which GM calls the headlamp switch) is a very easy affair and can be done with a multimeter... and I'll show you how.
Before I continue, I want to let you know that there's one more article that may help you. This article deals with testing the Low-High Beam headlight dimmer switch and will help you test a ‘no low beams’ or a ‘no high beams’ problem and you can find it here: How to Test the Low-High Beam Headlight Dimmer Switch.
To help you make sure this article applies to your specific Chevrolet or GMC pickup, van, mini-van or SUV, this article will help you test the following headlight switch part #'s:
If this headlight switch tutorial does not apply to your GM pickup or SUV... there's one more headlight switch tutorial for 1994 and older GM pickups that you can find here: How to Test the Headlight Switch (GM 1990-1994).
To help you navigate this article, here are its main points:
The most common and the most obvious symptom of a BAD headlight switch is that the headlights (headlamps) will not work. You'll also see:
With the help of this ‘How to Test’ article, you'll be able to say without a doubt that either the headlamp dimmer switch is BAD or not.
Since the headlight switch is part of a much larger system... if the test results confirm the headlight switch is OK, then you can avoid having to waste time and money replacing it.
The cool thing is, is that you don't need any expensive tools to check the headlight switch yourself.
Here's a basic list of tools you'll need:
As you can see from the list above, it's nothing that's gonna' break the bank.
The headlamp dimmer switch has a total of 11 wires (circuits) sticking out of its connector.
Each one has a specific job to do... but don't worry, we don't have to test them all to find out why the headlamps (or park lamps) are not working.
If you look closely at the headlight switch connector, you'll see that the letters A-H are molded on the top row, and that letters J-S are molded onto the bottom row. I'll be using these same letters for the circuit descriptions (photo 2 of 2 shows the location of the letters on the connector).
These are the circuit descriptions of the headlight and dimmer switch
|Headlight Dimmer Switch Pin outs|
|C||Red||Battery Fused Feed|
|D||Pink||Ignition Fused Feed|
|E||Dark Green||Instrument Panel Lamps Dimmer Switch|
|G||Yellow||Headlamp Switch Output|
|H||Orange||Battery Fused Feed|
|L||Purple||Interior Lamp Defeat Switch|
|N||Purple w/ White Stripe||LED Dimming Signal|
|S||Brown||Park Lamp Feed|
“Math is fun, it teaches you life and death information... like when you’re cold,
you should go to a corner since it’s 90° there.”