For 1990-2009 cars

Step | Action | Yes | No
--- | --- | --- | ---
Schematic Reference: Interior Lights Schematics
1 | Did you review the Lighting System Description and Operation and perform the necessary inspections? | Go to Step 2 | Go to Symptoms - Lighting Systems
2 | Verify that the back up lamps are inoperative. Does the system operate normally? | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3
3 |

1. Turn the ignition switch to the ON position.
2. Disconnect the park/neutral position (PNP) switch connector.
3. Using a test lamp inspect the corresponding cavities of the appropriate drivetrain:

• | Cavity 4 (4 SP A/T)

• | Cavity 6 (3 SP A/T)

Does the test lamp illuminate?

Go to Step 5

Go to Step 4

4 |

1. Turn the ignition switch to the ON position.
2. Disconnect the backup lamp switch connector.
3. Using a test lamp inspect cavity 2 of the backup lamp switch.

Does the test lamp illuminate?

Go to Step 7

Go to Step 6

5 | Repair the open in the battery positive voltage circuit between the SP258, C2 and the park/neutral position switch connector. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 17 | --
6 | Repair the open in the battery positive voltage circuit between the SP258, C2 and the backup lamp switch connector cavity 2. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 17 | Go to Step 8
7 | Repair the open in the battery positive voltage circuit between cavity C1 of SP258 and cavity 9 of connector C2 of junction block 2. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 17 | --
8 | With the park/neutral position switch connector still disconnected;

1. Put the vehicle into reverse.
2. Test for high resistance between cavities:

• | 4 and 8 (4 SPD A/T)

• | 5 and 6 (3 SPD A/T)

Did you find any high resistance in the circuit?

Go to Step 14

Go to Step 9

9 | With the park/neutral position switch connector still disconnected;

1. Put the vehicle into reverse.
2. Test for high resistance between cavities 1 and 2 of the backup lamp switch.

Did you find any high resistance in the circuit?

Go to Step 11

Go to Step 10

10 | Replace the park/neutral position switch. Refer to Park/Neutral Position Switch Replacement in Automatic Transmission. Is the replacement complete? | Go to Step 17 | --
11 | Test for open between cavity 9 of connector C3 of junction block 1 and connector cavities:

• | 8 (4 SPD A/T)

• | 5 (3 SPD A/T)

Is an open condition present?

Go to Step 13

Go to Step 12

12 | Replace the backup lamp switch. Refer to Backup Lamp Switch Replacement . Is the replacement complete? | Go to Step 17 | --
13 | Test for an open between cavity 9 of connector C3 of junction block 1 and connector cavity 1 of the backup lamp switch. Is an open condition present? | Go to Step 15 | Go to Step 16
14 | Repair the open in the backup lamp supply voltage circuit between cavity 9 of connector C3 of junction block 1 and the park/neutral position switch (PNP) connector. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | Go to Step 17 | --
15 | Repair the open in the backup lamp supply voltage circuit between cavity 9 of connector C3 of junction block 1 and cavity 1 of the backup lamp switch. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | Go to Step 17 | --
16 | Repair the open in the backup lamp supply voltage circuit between the junction block 1, connector C3 cavity 9 and SP450. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | Go to Step 17 | --
17 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 3