For 1990-2009 cars

## Headlamps - Low Beams On with Headlamp Switch Off 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. Turn the ignition switch to the OFF position.
2. Disconnect the headlamps switch connector.

Do the headlamps go out?

--

Go to Step 7

Go to Step 3

3 | Disconnect the headlamp dimmer switch connector C202. Do the headlamps go out? | -- | Go to Step 10 | Go to Step 4
4 | Disconnect the lamp control module (LCM) connector C2. Do the headlamps go out? | -- | Go to Step 9 | Go to Step 5
5 | Disconnect the LCM connector C1. Do the headlamps go out? | -- | Go to Step 9 | Go to Step 6
6 | Repair the short to battery positive voltage (B+) in the following wiring:

• | Low beams: CKT 12 (TAN)

• | High beams: CKT 11 (LT GRN).

Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Headlight System Check

--

7 | Inspect for a short to ground in CKT 103 (WHT). Refer to Testing for Short to Ground in Wiring Systems. Is CKT 103 OK? | -- | Go to Step 8 | Go to Step 12
8 | 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 | --
9 | Replace the LCM. Is the repair complete? | -- | Go to Headlight System Check | --
10 | Inspect for a short to ground in CKT 524 (PPL). Refer to Testing for Short to Ground in Wiring Systems. Is CKT 524 OK? | -- | Go to Step 11 | Go to Step 12
11 | Replace the headlamp dimmer switch. Refer to Dimmer Switch Assembly - Disassemble - Off Vehicle or Dimmer Switch Assembly - Assemble - Off Vehicle in Steering Wheel and Column-Tilt. Is the repair complete? | -- | Go to Headlight System Check | --
12 | Repair the suspect wiring. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Headlight System Check | --

## Headlamps - Low Beams On with Headlamp Switch Off 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. Turn the ignition switch to the OFF position.
2. Disconnect the headlamp switch connector.

Do the headlamps go out?

--

Go to Step 6

Go to Step 3

3 | Remove the headlamp relay position J from the RH IP fuse block. Do the headlamps go out? | -- | Go to Step 7 | Go to Step 4
4 | Disconnect the lamp control module (LCM) connector C1. Do the headlamps go out? | -- | Go to Step 9 | Go to Step 5
5 | Disconnect the headlamp dimmer switch connector C202. Do the headlamps go out? | -- | Go to Step 10 | Go to Step 12
6 | 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 | --
7 | Inspect for a short to the battery positive voltage (B+) in CKT 10 (YEL). Refer to Testing for Continuity in Wiring Systems. Is CKT 10 OK? | -- | Go to Step 8 | Go to Step 13
8 | Replace the headlamp relay position J in the RH IP fuse block. Is the repair complete? | -- | Go to Headlight System Check | --
9 | Replace the LCM. Is the repair complete? | -- | Go to Headlight System Check | --
10 | Inspect for a short to the battery positive voltage (B+) in CKT 1346 (LT BLU). Refer to Testing for Continuity in Wiring Systems. Is CKT 1346 OK? | -- | Go to Step 11 | Go to Step 13
11 | Replace the headlamp dimmer switch. Refer to Dimmer Switch Assembly - Disassemble - Off Vehicle or Dimmer Switch Assembly - Assemble - Off Vehicle in Steering Wheel and Column-Tilt. Is the repair complete? | -- | Go to Headlight System Check | --
12 | Repair the short to the battery positive voltage (B+) in the following wiring:

• | Low beams: CKT 12 (TAN)

• | High beams: CKT 11 (LT GRN).

Refer to Wiring Repairs in Wiring Systems.

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 - Low Beams On with Headlamp Switch Off Pontiac

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. Turn the ignition switch to the OFF position.
2. Disconnect the headlamps switch connector.

Do the headlamps go out?

--

Go to Step 10

Go to Step 3

3 | Disconnect the lamp control module (LCM) connector C1. Do the headlamps go out? | -- | Go to Step 11 | Go to Step 4
4 | Disconnect the headlamp dimmer switch connector C202. Do the headlamps go out? | -- | Go to Step 12 | Go to Step 5
5 | Is the vehicle equipped with lamp monitoring? | -- | Go to Step 6 | Go to Step 14
6 | Disconnect the following lamp monitor control module connectors:

• | C1

• | C2

Do the headlamps go out?

--

Go to Step 7

Go to Step 9

7 | Inspect for a short to battery positive voltage (B+) in the following wiring:

• | Low beams: CKT 1312 (TAN)

• | High beams: CKT 1311 (LT GRN).

Refer to Wiring Repairs in Wiring Systems.

Is CKT 1312 or CKT 1311 OK?

--

Go to Step 8

Go to Step 9

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 short to the battery positive voltage (B+) in the following wiring:

• | Low beams: CKT 1312 (TAN)

• | High beams: CKT 1311 (LT GRN).

Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Headlight System Check

--

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 | Replace the LCM. Is the repair complete? | -- | Go to Headlight System Check | --
12 | Inspect for a short to the battery positive voltage (B+) in CKT 10 (YEL). Refer to Testing for Continuity in Wiring Systems. Is CKT 10 OK? | -- | Go to Step 13 | Go to Step 15
13 | Replace the headlamp dimmer switch. Refer to DTC P1133 HO2S Insufficient Switching Sensor 1 in Steering Wheel and Column-Tilt. Is the repair complete? | -- | Go to Headlight System Check | --
14 | Repair the short to the battery positive voltage (B+) in the following wiring:

• | Low beams: CKT 12 (TAN).

• | High beams: CKT 11 (LT GRN).

Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Headlight System Check

--

15 | Repair the short to the battery positive voltage (B+) in CKT 10 (YEL). Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Headlight System Check | --