For 1990-2009 cars

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
Important: A short to ground will cause an open fuse(s). Before performing this diagnostic procedure, inspect the fuse(s) for an open.
1 |

1. Inspect the body control module (BCM) for DTCs. Refer to Body Control Module System Check in Body Control System.
2. Correct any of the current DTCs before preceding with this diagnosis.

Are all of the code setting conditions corrected?

--

Go to Step 2

Go to Step 12

2 |

1. Connect a Scan Tool to the data link connector (DLC).
2. Use the Scan Tool in order to command the headlamps ON.

Do the headlamps light?

--

Go to Step 12

Go to Step 3

3 | Backprobe the turn/headlamp switch assembly with a test lamp between terminal 36 of connector C1 and ground. Does the test lamp light? | -- | Go to Step 4 | Go to Step 5
4 |

1. Exchange the automatic lamp control relay with a known good relay from the underhood junction block.
2. Use the Scan Tool in order to command the headlamps ON.

Do the headlamps light?

--

Go to Step 6

Go to Step 7

5 | Replace the turn/headlamp switch assembly. Refer to Multifunction Turn Signal Lever Replacement - On Vehicle in Steering Wheel and Column-Standard. Is the repair complete? | -- | Go to Daytime Running Lights (DRL) System Check | --
6 | Replace the faulty relay. Is the repair complete? | -- | Go to Daytime Running Lights (DRL) System Check | --
7 | Backprobe the underhood junction block with a test lamp between terminal B3 of connector C3 and ground. Does the test lamp light? | -- | Go to Step 8 | Go to Step 9
8 | Backprobe the underhood junction block using a J 39200 DMM and measure the resistance between terminal A10 of connector C3 and ground. Is the resistance measured within the specified range? | 0-2 ohms | Go to Step 10 | Go to Step 11
9 | Repair the open in CKT 306 between the underhood junction block and the turn/headlamp switch assembly. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Daytime Running Lights (DRL) System Check | --
10 | Backprobe the underhood junction block with a fused jumper between terminal A9 of connector C3 and ground. Do the headlamps light? | -- | Go to Step 12 | Go to Step 13
11 | Repair the open in CKT 150 between the underhood junction block and ground splice pack G201. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Daytime Running Lights (DRL) System Check | --
12 | Replace the BCM. Refer to Body Control Module Replacement in Body Control Systems. Is the repair complete? | -- | Go to Daytime Running Lights (DRL) System Check | --
13 | Replace the underhood junction block. Refer to Underhood Fuse Block Replacement in Engine Electrical. Is the repair complete? | -- | Go to Daytime Running Lights (DRL) System Check | --