Daytime Running Lamps (DRL) On with Headlamp Switch On. Chevrolet Blazer

For 1990-2009 cars only

Makes 🢒 Chevrolet 🢒 2002 🢒 Blazer - 4WD 🢒 Body and Accessories 🢒 Lighting Systems 🢒 Daytime Running Lamps (DRL) On with Headlamp Switch On

Daytime Running Lamps (DRL) On with Headlamp Switch On Standard

Step

Action

Yes

Schematic Reference: Headlights/Daytime Running Lights (DRL) Schematics

Did you perform the Lighting Systems Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Lighting Systems

Verify that the DRL headlamps are always on.

Do the DRL headlamps operate normally?

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 3

Use the scan tool to inspect for the following related Body Control Module (BCM) Data/ Input Parameters and Output Controls. Refer to Scan Tool Data List for typical values and definitions:

•	Headlamp Ambient Light Sensor

•	Park Brake Switch

•	Auto Headlamps

•	Headlamp Relay Feedback

•	Daytime Running Lamps Relay

•	Headlamp Power Relay

•	Left Turn Signal

•	Right Turn Signal

•	High Beam Switch

•	Flash to Pass Switch

Did you find and correct a condition?

Go to Step 9

Go to Step 4

Remove the DRL relay from the underhood fuse block.

Do the daytime running lamps remain on?

Go to Step 7

Go to Step 5

Make sure the ignition switch is in the OFF position.
Remove the headlamp grounding relay in the body relay block.
Disconnect the BCM connector C1.
Using the J 39200 digital multimeter (DMM), check for continuity to ground in the DRL relay control circuit. Refer to Circuit Testing in Wiring Systems.

Is continuity present?

Go to Step 6

Go to Step 8

Repair the short to ground in the DRL relay control circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 9

Repair the short to ground in the left headlamp high beam supply voltage circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 9

Replace the DRL relay.

Did you complete the repair?

Go to Step 9

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 3

Daytime Running Lamps (DRL) On with Headlamp Switch On ZR2

Step

Action

Yes

Schematic Reference: Headlights/Daytime Running Lights (DRL) Schematics

Did you perform the Lighting Systems Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Lighting Systems

Verify that the DRL headlamps are always on.

Do the DRL headlamps operate normally?

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 3

Use the scan tool to inspect for the following related Body Control Module (BCM) Data/ Input Parameters and Output Controls. Refer to Scan Tool Data List for typical values and definitions:

•	Headlamp Ambient Light Sensor

•	Park Brake Switch

•	Auto Headlamps

•	Headlamp Relay Feedback

•	Daytime Running Lamps Relay

•	Headlamp Power Relay

•	Left Turn Signal

•	Right Turn Signal

•	High Beam Switch

•	Flash to Pass Switch

Did you find and correct a problem?

Go to Step 9

Go to Step 4

Remove the DRL (ZR2) relay.

Do the daytime running lamps remain on?

Go to Step 6

Go to Step 5

Make sure the ignition switch is in the OFF position.
Disconnect the BCM connector C 1.
Using the J 39200 digital multimeter (DMM), check for continuity to ground of the DRL relay control circuit at the BCM connector. Refer to Circuit Testing in Wiring Systems.

Is continuity present?

Go to Step 7

Go to Step 8

Repair the short to ground in the headlamp dimmer switch low beam signal circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 9

Repair the short to ground in the DRL relay control circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 9

Replace the DRL relay.

Did you complete the repair?

Go to Step 9

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 3