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Reverse Lamps Malfunction — Automatic Transmission

Diagnostic Instructions
    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    • Diagnostic Procedure Instructions provides an overview of each diagnostic category.

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Park/Neutral Position (PNP) Switch B+

1

1

1

--

Reverse Lamps Control

1

1

1

--

Reversing Lamp - Left Ground

--

1

--

--

Reversing Lamp - Right Ground

--

1

--

--

1. Backup Lamps Malfunction

Circuit/System Description

Battery voltage is applied from the F19DA fuse located in the I/P fuse block to the park/neutral position (PNP) switch when the ignition switch is in the RUN or CRANK positions. When the transmission is placed in the REVERSE position, the park/neutral position (PNP) switch contacts close providing battery voltage to the reversing lamps. The reversing lamps are permanently grounded at G401 for the left and G400 for the right. With both power and ground the reversing lamps illuminate. Once the driver moves the gear selector out of the REVERSE position, the park/neutral position (PNP) switch contacts open and the reversing lamps turn OFF.

Circuit/System Testing
  1. Ignition OFF, disconnect the wiring harness plug at the inoperative reversing lamp.
  2. Ignition OFF, exterior lamps OFF, test for less than 5 Ω between the ground circuit terminal B and ground.
    3. ⇒If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Connect the wiring harness plug at the inoperative reversing lamp.
  4. Ignition OFF, disconnect the wiring harness plug at the park/neutral position (PNP) switch.
  5. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal 1 and ground.
    6. ⇒If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
  6. Verify that a test lamp does not illuminate between the control circuit terminal 5 and ground.
    7. ⇒If the test lamp illuminates, test the control circuit for a short to voltage.
  7. Connect a 10 A fused jumper wire between the B+ circuit terminal 1 and the control circuit terminal 5. Ignition ON, verify the reversing lamps are illuminated.
    8. ⇒If the reversing lamps do not illuminate, test the control circuit for a short circuit to ground or an open/high resistance. If the circuit tests normal, test or replace the inoperative reversing lamp.
  8. If all circuits test normal, replace the park/neutral position (PNP) switch.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Park/Neutral Position Switch Replacement
    •  Tail Lamp Replacement
   


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