For 1990-2009 cars

## Headlamps Inoperative - Low Beams Buick

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Did you perform the Headlight System Check? | -- | Go to Step 2 | Go to Headlight System Check
2 |

1. Disconnect the lamp control module (LCM) connector C2.
2. Connect a J 39200 digital multimeter (DMM) between the LCM connector C2 cavity G (ORN) and ground.

Is the voltage within the specified range?

10-15 V

Go to Step 3

Go to Step 9

3 | Connect the DMM between the LCM connector C2 cavity G (ORN) and cavity E (BLK). Is the voltage within the specified range? | 10-15 V | Go to Step 4 | Go to Step 10
4 |

1. Disconnect the LCM connector C1.
2. Connect the DMM between the LCM connector C2 cavity G (ORN) and the LCM connector C1 cavity B4 (BLK/WHT).

Is the voltage within the specified range?

10-15 V

Go to Step 5

Go to Step 11

5 | Connect the DMM between the LCM connector C2 cavity G (ORN) and the LCM connector C1 cavity B5 (BLK/WHT) Is the voltage within the specified range? | 10-15V | Go to Step 6 | Go to Step 11
6 |

1. Reconnect the LCM connector C1 and connector C2.
2. Disconnect the headlamp switch connector.
3. Connect a fused jumper between the headlamp switch connector cavity 6 (WHT) and ground.

Do the low beam headlights turn on?

--

Go to Step 12

Go to Step 7

7 |

1. Disconnect the LCM connector C2.
2. Connect a fused jumper between the LCM connector C2 cavity G (ORN) and cavity F (TAN).

Do the low beam headlights turn on?

--

Go to Step 14

Go to Step 8

8 | Repair the open in CKT 12 (TAN) between the LCM and S120. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Headlight System Check | --
9 | Repair the open in CKT 1740 (ORN) between the right rear fuse block and the LCM. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Headlight System Check | --
10 | Repair the open in CKT 150 (BLK) between S290 and the LCM. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Headlight System Check | --
11 | Repair the open in CKT 351 (BLK/WHT) between S263 and the LCM. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Headlight System Check | --
12 | Test for an open in CKT 150 (BLK) between S273 and the headlamp switch. Refer to Testing for Continuity in Wiring Systems. Is CKT 150 OK? | -- | Go to Step 13 | Go to Step 16
13 | Replace the headlamp switch. Refer to Headlamp Switch Replacement . Is the repair complete? | -- | Go to Headlight System Check | --
14 | Test for an open in CKT 103 (WHT) between the LCM and the headlamp switch. Refer to Testing for Continuity in Wiring Systems. Is CKT 103 OK? | -- | Go to Step 15 | Go to Step 16
15 | Replace the LCM. Is the repair complete? | -- | Go to Headlight System Check | --
16 | Repair the suspect wiring. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Headlight System Check | --

## Headlamps Inoperative - Low Beams Oldsmobile

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Did you perform the Headlight System Check? | -- | Go to Step 2 | Go to Headlight System Check
2 |

1. Disconnect the lamp control module (LCM) connector C2.
2. Connect a J 39200 digital multimeter (DMM) between the LCM connector C2 cavity E (ORN) and ground.

Is the voltage within the specified range?

10-15 V

Go to Step 3

Go to Step 11

3 |

1. Disconnect the LCM connector C1.
2. Connect the DMM between the LCM connector C2 cavity E (ORN) and the LCM connector C1 cavity A5 (BLK/WHT).

Is the voltage within the specified range?

10-15 V

Go to Step 4

Go to Step 12

4 | Connect the DMM between the LCM connector C2 cavity E (ORN) and the LCM connector C1 cavity B6 (BLK/WHT). Is the voltage within the specified range? | 10-15 V | Go to Step 5 | Go to Step 12
5 |

1. Place the headlamp switch in the ON position.
2. Connect the DMM between the LCM connector C2 cavity E (ORN) and connector C1 cavity B1 (WHT).

Is the voltage within the specified range?

10-15 V

Go to Step 6

Go to Step 13

6 | Connect a fused jumper between the LCM connector C2 cavity E (ORN) and cavity D (LT BLU). Do the low beam headlights light? | -- | Go to Step 18 | Go to Step 7
7 |

1. Disconnect the headlamp dimmer switch connector C202.
2. Connect a fused jumper between the LCM connector C2 cavity E (ORN) and the headlamp dimmer switch connector C202 cavity E12 (TAN).

Do the low beam headlights light?

--

Go to Step 9

Go to Step 8

8 | Repair the open in CKT 12 (TAN) between the headlamp dimmer switch connector C202 and S120. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Headlight System Check | --
9 | Test for an open in CKT 1346 (LT BLU) between the LCM and the headlamp dimmer switch connector C202. Refer to Testing for Continuity in Wiring Systems. Is CKT 1346 OK? | -- | Go to Step 10 | Go to Step 19
10 | Replace the headlamp dimmer switch. Refer to Multifunction Turn Signal Lever Replacement - On Vehicle in Steering Wheel and Column - Tilt. Is the repair complete? | -- | Go to Headlight System Check | --
11 | Repair the open in CKT 1740 (ORN) between the right rear fuse block and the LCM. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Headlight System Check | --
12 | Repair the open in CKT 351 (BLK/WHT) between S263 and the LCM. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Headlight System Check | --
13 | Use the DMM in order to backprobe the LCM connector C2 between cavity E (ORN) and the headlamp dimmer switch connector C202 cavity E9 (WHT). Is the voltage within the specified range? | 10-15 V | Go to Step 17 | Go to Step 14
14 | Use the DMM in order to backprobe the LCM connector C2 between cavity E (ORN) and the headlamp switch connector C202 cavity E6 (BLK/WHT). Is the voltage within the specified range? | 10-15 V | Go to Step 16 | Go to Step 15
15 | Repair the open in CKT 351 (BLK/WHT) between the headlamp switch connector C202 and S263. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Headlight System Check | --
16 | Replace the headlamp switch. Refer to Multifunction Turn Signal Lever Replacement - On Vehicle in Steering Wheel and Column - Tilt. Is the repair complete? | -- | Go to Headlight System Check | --
17 | Repair the open in CKT 103 (WHT) between the LCM and the headlamp switch connector C202. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Headlight System Check | --
18 | Replace the LCM. Is the repair complete? | -- | Go to Headlight System Check | --
19 | Repair the open in CKT 1346 (LT BLU) between the LCM and the headlamp dimmer switch connector C202. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Headlight System Check | --