For 1990-2009 cars

Step | Action | Yes | No
--- | --- | --- | ---
Schematic Reference: Headlights/Daytime Running Lights (DRL) 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 low or high beam headlamps are always ON. Do the low and high beam headlamps operate normally? | Go to Testing for Intermittent Conditions and Poor Connections | Go to Step 3
3 | Does the wiper activated headlamp (WAH) function of the wiper system operate normally? | Go to Step 6 | Go to Step 4
4 | With the key in RUN and the wiper switch in the OFF position, use the scan tool to monitor the Front Wipers Active input parameter. Does the scan tool parameter display Inactive? | Go to Step 13 | Go to Step 5
5 | Test the windshield wiper switch signal 1 circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 21 | Go to Step 20
6 | Can you illuminate both low and high beam headlamps at the same time when activating the headlamp dimmer switch? | Go to Step 15 | Go to Step 7
7 |

1. Place the headlamp and panel dimmer switch in the OFF position.
2. Turn the ignition ON with the engine OFF.
3. With a scan tool, observe the Headlamp OFF Switch data parameter in the Body Control Module (BCM) data list.

Does the scan tool display Active?

Go to Step 10

Go to Step 8

8 |

1. Disconnect the headlamp and panel dimmer switch. Refer to Headlamp Switch Replacement .
2. Place a fused jumper between the headlamp switch headlamps OFF signal circuit and low reference circuit terminals.

Does the scan tool display Active?

Go to Step 14

Go to Step 9

9 | Test for an open or high resistance in one of the following headlamp and panel dimmer switch circuits. Refer to Circuit Testing and Wiring Repairs .

• | The headlamp switch headlamps OFF signal

• | The low reference circuit

Did you find and correct a condition?

Go to Step 21

Go to Step 13

10 | Remove the headlamp relay. Refer to Relay Replacement . Do the low or high beam headlamps remain always ON? | Go to Step 16 | Go to Step 11
11 | Test for a ground signal at the headlamp relay control circuit connector terminal. Refer to Circuit Testing and Electrical Center Identification Views . Is a ground control signal present? | Go to Step 12 | Go to Step 18
12 | Test for a short to ground in the headlamp relay control circuit. Refer to Circuit Testing and Electrical Center Identification Views . Did you find and correct a condition? | Go to Step 21 | Go to Step 13
13 | Inspect for poor connections at the harness connector of the BCM. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 21 | Go to Step 17
14 | Inspect for poor connections at the harness connector of the headlamp and panel dimmer switch. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 21 | Go to Step 19
15 | Repair the short to ground in the right or left low or high beam headlamp ground circuit. Refer to Circuit Testing and Wiring Repairs . Did you complete the repair? | Go to Step 21 | --
16 | Repair the short to voltage in the right or left low beam headlamp supply voltage circuit. Refer to Wiring Repairs . Did you complete the repair? | Go to Step 21 | --
17 | Replace the BCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | Go to Step 21 | --
18 | Replace the headlamp relay. Refer to Relay Replacement . Did you complete the repair? | Go to Step 21 | --
19 | Replace the headlamp and panel dimmer switch. Refer to Headlamp Switch Replacement . Did you complete the repair? | Go to Step 21 | --
20 | Replace the turn signal/multifunction switch. Refer to Turn Signal Multifunction Switch Replacement . Did you complete the repair? | Go to Step 21 | --
21 |

1. Use the scan tool in order to clear any induced DTCs.
2. Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 3