For 1990-2009 cars

## Backup Lamps Inoperative Buick

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

1. Disconnect the park/neutral position switch connector.
2. Set the ignition switch to RUN.
3. Measure the voltage to ground at the park/neutral position switch connector C1 cavity B (PNK).

Is the voltage within the specified range?

10-15 V

Go to Step 3

Go to Step 5

3 | Connect a fused jumper between the park/neutral position switch connector C1 cavity B (PNK) and cavity F (LT GRN). Do the backup lamps turn on? | -- | Go to Step 4 | Go to Step 6
4 | Replace the park/neutral position switch. Refer to Park/Neutral Position Switch Replacement in Automatic Transaxle-4T65-E. Is the repair complete? | -- | Go to Backup Lamp System Check | --
5 | Repair the open or short to ground in CKT 139 (PNK). Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Backup Lamp System Check | --
6 | Inspect CKT 24 (LT GRN) for an open between S432 and the park/neutral position switch. Refer to Testing for Continuity in Wiring Systems. Is CKT 24 OK? | -- | Go to Step 7 | Go to Step 8
7 | Repair the open in CKT 1250 (BLK) between S425 and G401. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Backup Lamp System Check | --
8 | Repair the suspect wiring. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Backup Lamp System Check | --

## Backup Lamps Inoperative Oldsmobile

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

1. Disconnect the park/neutral position switch connector.
2. Set the ignition switch to RUN.
3. Measure the voltage between the park/neutral position switch connector C114 cavity D (PNK) and ground.

Is the voltage within the specified range?

10-15 V

Go to Step 3

Go to Step 5

3 | Connect a fused jumper between the park/neutral position switch connector C114 cavity D (PNK) and cavity F (LT GRN). Do the backup lamps turn on? | -- | Go to Step 4 | Go to Step 6
4 | Replace the park/neutral position switch. Refer to PNP Switch Replacement in Automatic Transaxle-4T80-E. Is the repair complete? | -- | Go to Backup Lamp System Check | --
5 | Repair the open or short to ground in CKT 139 (PNK). Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Backup Lamp System Check | --
6 | Test CKT 24 (LT GRN) for an open between S432 and the park/neutral position switch. Refer to Testing for Continuity in Wiring Systems. Is CKT 24 OK? | -- | Go to Step 7 | Go to Step 8
7 | Repair the open in CKT 1250 (BLK) between S425 and G401. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Backup Lamp System Check | --
8 | Repair the suspect wiring. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Backup Lamp System Check | --