GM Service Manual Online
For 1990-2009 cars only

Step

Action

Yes

No

Schematic Reference: Exterior Lights Schematics

Connector End View Reference: Lighting Systems Connector End Views or Data Communication Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

Verify that the off-road lamps are inoperative.

Do the off-road lamps operate normally?

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 3

3

Is only one off-road lamp inoperative?

Go to Step 4

Go to Step 6

4

Test the supply voltage circuit of the inoperative lamp for high resistance, short to ground or an open. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 21

Go to Step 5

5

Test the ground circuit of the inoperative lamp for high resistance, or an open. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 21

Go to Step 13

6

Connect a test lamp between the battery positive voltage circuit of the off-road lamps switch, and a good ground.

Does the test lamp illuminate?

Go to Step 7

Go to Step 16

7

Connect a 3-amp fused jumper wire between the battery positive circuit and the off-road lamp relay control circuit of the off-road lamps switch.

Do the off-road lamps illuminate?

Go to Step 15

Go to Step 8

8

Connect a 3-amp fused jumper wire between the battery positive circuit and the off-road lamp supply voltage circuit of the off-road lamps relay.

Do the off-road lamps illuminate?

Go to Step 9

Go to Step 11

9

Test the off-road lamp relay control circuit of the off-road lamps switch for high resistance, short to ground or an open. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 21

Go to Step 10

10

Test the ground circuit of the off-road lamps relay for high resistance, or an open. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 21

Go to Step 11

11

Test the battery positive voltage circuit of the off-road lamps relay for high resistance, or an open. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 21

Go to Step 12

12

Test the ground circuit of the off-road lamps for high resistance, or an open. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 21

Go to Step 17

13

Inspect for poor connections at the harness connector of the off-road lamp. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 21

Go to Step 18

14

Inspect for poor connections at the harness connector of the off-road lamps relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 21

Go to Step 19

15

Inspect for poor connections at the harness connector of the off-road lamps switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 21

Go to Step 20

16

Repair the battery positive voltage circuit of the off-road lamps switch. Refer to Wiring Repairs .

Did you complete the repair?

Go to Step 21

--

17

Repair the supply voltage circuit of the off-road lamps. Refer to Wiring Repairs .

Did you complete the repair?

Go to Step 21

--

18

Replace the inoperative off-road lamp. Refer to Off Road Lamp Bulb Replacement .

Did you complete the replacement?

Go to Step 21

--

19

Replace the inoperative off-road lamps relay. Refer to Relay Replacement .

Did you complete the replacement?

Go to Step 21

--

20

Replace the off-road lamps switch. Refer to Off Road Lamp Switch Replacement .

Did you complete the replacement?

Go to Step 14

--

21

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 3