GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

1

Check the DRL fuse for an open.

Is the DRL fuse open?

--

Go to Step 2

Go to Step 3

2

Repair short to ground in circuit 1239.

Is the repair complete?

--

Go to Exterior Lights System Check or Headlight System Check

--

3

Check the HVAC fuse for an open.

Is the HVAC fuse open?

--

Go to Step 4

Go to Step 5

4

Repair short to ground in circuit 41.

Is the repair complete?

--

Go to Exterior Lights System Check or Headlight System Check

--

5

Check for a poor connection or open in circuit 10.

Is circuit 10 OK?

--

Go to Step 7

Go to Step 6

6

Repair poor connection or open in circuit 10.

Is the repair complete?

--

Go to Exterior Lights System Check or Headlight System Check

--

7

Check for Body Control Module (BCM) Diagnostic Trouble Codes (DTCs). Refer to Diagnostic Trouble Code (DTC) Displaying in Body Control System for more information.

Are there any BCM DTCs preset?

--

Go to Body Control Module Diagnostic Information in Body Control System

Go to Step 8

8

  1. Turn the ignition switch to the ON position.
  2. Release the parking brake.
  3. Apply a bright light to the daytime running lamps ambient light sensor.

Do the front turn signal lamps turn on?

--

Go to Step 21

Go to Step 9

9

With a test lamp, backprobe between the daytime running lamps control module harness connector C2 terminal C to ground.

Is the test lamp on?

--

Go to Step 11

Go to Step 10

10

Repair poor connection or open in circuit 1239.

Is the repair complete?

--

Go to Exterior Lights System Check or Headlight System Check

--

11

Using a test lamp, backprobe between the daytime running lamps control module harness connector C2 terminal F to ground.

Is the test lamp on?

--

Go to Step 13

Go to Step 12

12

Repair poor connection or open in circuit 41 between fuse block terminal B4 and the daytime running lamps control module harness connector C2 terminal F.

Is the repair complete?

--

Go to Exterior Lights System Check or Headlight System Check

--

13

Using a test lamp, backprobe between the daytime running lamps control module harness connector C2 terminal C and terminal A.

Is the test lamp on?

--

Go to Step 15

Go to Step 14

14

Repair poor connection or open in circuit 1750 between the daytime running lamps control module harness connector and G201.

Is the repair complete?

--

Go to Exterior Lights System Check or Headlight System Check

--

15

Using a test lamp, backprobe between B+ and the daytime running lamps control module harness connector C1 terminal F.

Is the test lamp on?

--

Go to Step 16

Go to Step 14

16

With a test lamp, backprobe between B+ and the daytime running lamps control module harness connector C2 terminal E.

Is the test lamp on?

--

Go to Step 17

Go to Step 20

17

  1. Disconnect the park brake indicator switch.
  2. Leave the test lamp in the same place.

Is the test lamp on?

--

Go to Step 19

Go to Step 18

18

Adjust or replace the park brake indicator switch. Refer to Parking Brake Indicator Switch Replacement in Park Brake for service procedure.

Is the repair complete?

--

Go to Exterior Lights System Check or Headlight System Check

--

19

Repair short to ground in circuit 1830.

Is the repair complete?

--

Go to Exterior Lights System Check or Headlight System Check

--

20

Replace the daytime running lamps control module. Refer to Daytime Running Lights (DRL) Control Module Replacement for service procedure.

Is the repair complete?

--

Go to Exterior Lights System Check or Headlight System Check

--

21

Disconnect the daytime running lamps ambient light sensor.

Do the low beam headlamps and park lamps turn on?

--

Go to Step 23

Go to Step 22

22

Check for a short to ground in circuit 1137.

Is there a short in circuit 1137?

--

Go to Step 25

Go to Step 24

23

Replace the daytime running lamps ambient light sensor. Refer to Daytime Running Lamp (DRL) Ambient Light Sensor Replacement for service procedure.

Is the repair complete?

--

Go to Exterior Lights System Check or Headlight System Check

--

24

Repair short to ground in circuit 1137.

Is the repair complete?

--

Go to Exterior Lights System Check or Headlight System Check

--

25

Check for a short to ground in circuit 1138.

Is there a short in circuit 1138?

--

Go to Step 26

Go to Step 20

26

Repair short to ground in circuit 1138.

Is the repair complete?

--

Go to Exterior Lights System Check or Headlight System Check

--