This tutorial 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:
- AC Delco Part # D1530F.
- AC Delco Part # D1523H.
- AirTex, Wells Part # 1S1356.
- Standard Motor Products Part # DS876.
- Standard Motor Products Part # DS876T.
- OEM (Original Engine Management) Part # HLS31.
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).
Contents of this tutorial:
- Symptoms Of A Bad Headlamp Switch.
- What Tools Do I Need To Test The Headlight Switch?
- Circuit Descriptions Of The Headlight Switch Connector.
- TEST 1: Checking Power (Headlight Circuit).
- TEST 2: Fused Jumper Wire (Headlight Circuit).
- TEST 3: Checking Power (Park Lights Circuit).
- TEST 4: Fused Jumper Wire (Park Lights Circuit).
Symptoms Of A Bad Headlight Switch
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:
- Park lights do not come On.
- instrument cluster illumination does not work.
With the help of this ‘how to test’ tutorial, 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.
What Tools Do I Need To Test The Headlight Switch?
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:
- The multimeter can either be a digital one or an analog one.
- If you need to upgrade or buy a multimeter, check out my recommendation: Buying A Digital Multimeter For Automotive Diagnostic Testing (found at: easyautodiagnostics.com).
- A jumper wire.
- Ideally, this jumper wire should have an inline fuse attached to it.
- Now, a fused jumper is not necessary since you can use a regular wire as a jumper wire.
- Wire piercing probe.
- Although this tool is not an absolute must, if you do buy one, you'll realize just how easy it makes testing the voltages inside the wires.
- If you need to see what this tool looks like, you can see it here: Wire Piercing Probe.
As you can see from the list above, it's nothing that's gonna' break the bank.
Circuit Descriptions Of The Headlight Switch Connector
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.
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|