For 1990-2009 cars

## Headlamps Inoperative - Low Beams Buick

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

1. Disconnect the lamp control module (LCM) connector C1.
2. Connect a DMM from the LCM connector C1 cavity G (RED) to ground.

Is the voltage within the specified range?

10-15V

Go to Step 3

Go to Step 7

3 |

1. Disconnect the LCM connector C2.
2. Connect a DMM from the LCM connector C1 cavity G (RED) to connector C2 cavity B4 (BLK/WHT).
3. Connect a DMM from the LCM connector C1 cavity G (RED) to connector C2 cavity B5 (BLK/WHT).

Is the voltage within the specified range for both ground cavities?

10-15V

Go to Step 4

Go to Step 8

4 |

1. Reconnect the following LCM connectors:

• | C1

• | C2

2. Disconnect the headlamp switch connector.
3. Connect a fused jumper from the headlamp switch connector cavity J (WHT) to ground.

Do the low beam headlamps light?

--

Go to Step 9

Go to Step 5

5 |

1. Disconnect the LCM connector C1.
2. Connect a fused jumper from the LCM connector C1 cavity G (RED) to cavity F (TAN).

Do the low beam headlights light?

--

Go to Step 11

Go to Step 6

6 | Repair the open in CKT 12 (TAN). Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Headlight System Check | --
7 | Repair the open CKT 242 (RED) between the LH underhood fuse block and the LCM. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Headlight System Check | --
8 | Repair the open in CKT 251 (BLK/WHT) between S293 and the LCM. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Headlight System Check | --
9 | Inspect for an open in CKT 251 (BLK/WHT) between S293 and the headlamp switch. Refer to Testing for Continuity in Wiring Systems. Is CKT 251 OK? | -- | Go to Step 10 | Go to Step 13
10 | Replace the headlamp switch. Refer to Instrument Cluster Trim Panel Replacement in Instrument Panel, Gauges and Console. Is the repair complete? | -- | Go to Headlight System Check | --
11 | Inspect for an open in CKT 103 (WHT) between the headlamp switch and the LCM. Refer to Testing for Continuity in Wiring Systems. Is CKT 103 OK? | -- | Go to Step 12 | Go to Step 13
12 | Replace the LCM. Is the repair complete? | -- | Go to Headlight System Check | --
13 | Repair the suspect wiring. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Headlight System Check | --

## Headlamps Inoperative - Low Beams Pontiac

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

1. Disconnect the lamp control module (LCM) connector C1.
2. Connect a DMM from the LCM connector C1 cavity E (RED) to ground.

Is the voltage within the specified range?

10-15V

Go to Step 3

Go to Step 9

3 | Use a test lamp in order to backprobe the headlamp switch connector from cavity A (RED) to ground. Does the test lamp light? | -- | Go to Step 4 | Go to Step 10
4 |

1. Disconnect the headlamp switch connector.
2. Connect a fused jumper from the headlamp switch cavity A (RED) to cavity D (YEL).

Do the low beam headlamps light?

--

Go to Step 11

Go to Step 5

5 |

1. Leave the fused jumper in place.
2. Use a test lamp in order to backprobe the headlamp dimmer switch connector C202 from cavity C5 (YEL) to ground.

Does the test lamp light?

--

Go to Step 6

Go to Step 12

6 | Is the vehicle equipped with lamp monitoring? | -- | Go to Step 7 | Go to Step 13
7 |

1. Place the headlamp dimmer switch in the LOW position.
2. Disconnect the following lamp monitor control module connectors:

• | C1

• | C2

3. Connect a fused jumper from the lamp monitor control module connector C2 cavity R (TAN) to connector C1 cavity A (TAN).

Do the low beam headlamps light?

--

Go to Step 8

Go to Step 15

8 | Replace the lamp monitor control module. Refer to Instrument Panel Lamp Dimmer Replacement in Instrument Panel, Gauges and Console. Is the repair complete? | -- | Go to Headlight System Check | --
9 | Repair the open in CKT 242 (RED) between S201 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 242 (RED) between S201 and the headlamp switch. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Headlight System Check | --
11 | Replace the headlamp switch. Refer to Instrument Cluster Trim Panel Replacement in Instrument Panel, Gauges and Console. Is the repair complete? | -- | Go to Headlight System Check | Go to Step 13
12 | Repair the open in CKT 10 (YEL) between the headlamp switch and the headlamp dimmer switch connector C202. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Headlight System Check | --
13 | Inspect for an open in CKT 12 (TAN) between S257 and the headlamp dimmer switch connector C202. Refer to Testing for Continuity in Wiring Systems. Is CKT 12 OK? | -- | Go to Step 14 | Go to Step 17
14 | Replace the headlamp dimmer switch. Refer to Dimmer Switch Assembly - Disassemble - Off Vehicle and Dimmer Switch Assembly - Assemble - Off Vehicle in Steering Wheel and Column-Tilt. Is the repair complete? | -- | Go to Headlight System Check | --
15 | Inspect for an open in CKT 12 (TAN) between S257 and the lamp monitor control module. Refer to Testing for Continuity in Wiring Systems. Is CKT 12 OK? | -- | Go to Step 16 | Go to Step 17
16 | Inspect for an open in CKT 1312 (TAN) between the lamp monitor control module and S258. Refer to Testing for Continuity in Wiring Systems. Is CKT 1312 OK? | -- | Go to Step 11 | Go to Step 17
17 | 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 headlights system check? | -- | Go to Step 2 | Go to Headlight System Check
2 |

1. Disconnect the lamp control module (LCM) connector C1.
2. Connect a DMM from the LCM connector C1 cavity E (RED) to ground.

Is the voltage within the specified range?

10-15V

Go to Step 3

Go to Step 9

3 | Use a test lamp in order to backprobe the headlamp switch connector from cavity D (RED) to ground. Does the test lamp light? | -- | Go to Step 4 | Go to Step 10
4 |

1. Remove the headlamp relay position J from the RH IP fuse block.
2. Connect a DMM from the headlamp relay position J cavity 30 (RED) to ground.

Is the voltage within the specified range?

10-15V

Go to Step 5

Go to Step 11

5 |

1. Place the headlamp switch in the HEAD position.
2. Connect a DMM from the headlamp relay position J cavity 85 (YEL) to ground.

Is the voltage within the specified range?

10-15V

Go to Step 6

Go to Step 12

6 | Connect a DMM from the headlamp relay position J cavity 30 (RED) to cavity 86 (BLK). Is the voltage within the specified range? | 10-15V | Go to Step 7 | Go to Step 14
7 | Connect a fused jumper from the headlamp relay position J cavity 30 (RED) to cavity 87 (LT BLU). Do the low beam headlamps light? | -- | Go to Step 15 | Go to Step 8
8 |

1. Leave the fused jumper in place.
2. Use a test lamp in order to backprobe the headlamp dimmer switch connector C202 from cavity C5 (LT BLU) to ground.

Does the test lamp light?

--

Go to Step 17

Go to Step 16

9 | Repair the open in CKT 242 (RED) between S201 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 242 (RED) between S201 and the headlamp switch. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Headlight System Check | --
11 | Repair the open in CKT 242 (RED) between S201 and the RH IP fuse block. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Headlight System Check | --
12 | Inspect for an open in CKT 10 (YEL) between the headlamp switch and the RH IP fuse block. Refer to Testing for Continuity in Wiring Systems. Is CKT 10 OK? | -- | Go to Step 13 | Go to Step 19
13 | Replace the headlamp switch. Refer to Instrument Cluster Trim Panel Replacement in Instrument Panel, Gauges and Console. Is the repair complete? | -- | Go to Headlight System Check | --
14 | Repair the open in CKT 1450 (BLK) between the RH IP fuse block and S308. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Headlight System Check | --
15 | Replace the headlamp relay position J in the RH IP fuse block. Is the repair complete? | -- | Go to Headlight System Check | --
16 | Repair the open in CKT 1346 (LT BLU) between the RH IP fuse block and the headlamp dimmer switch connector C202. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Headlight System Check | --
17 | Inspect for an open in the CKT 12 (TAN) wiring between the headlamp dimmer switch connector C202 and S257. Refer to Testing for Continuity in Wiring Systems. Is CKT 12 OK? | -- | Go to Step 18 | Go to Step 19
18 | Replace the headlamp dimmer switch. Refer to Dimmer Switch Assembly - Disassemble - Off Vehicle and Dimmer Switch Assembly - Assemble - Off Vehicle in Steering and Column-Tilt. Is the repair complete? | -- | Go to Headlight System Check | --
19 | Repair the suspect wiring. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Headlight System Check | --