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Reverse Lamps Malfunction - MT

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

Reverse Gear Signal

1

1

2

--

1. Reverse Gear Lamp Inoperative

2. Reverse Gear Lamp Always ON

Circuit/System Description

When the transmission is placed in the reverse position, the engine control module (ECM) sends a serial data message to the body control module (BCM). The message indicates that the gear selector is in the reverse position. The BCM applies battery voltage to the reverse lamps. The reverse lamps are permanently grounded. Once the driver moves the gear selector out of the reverse position, a message is sent by the ECM via serial data requesting the BCM to remove battery voltage from the reverse lamp control circuit.

Reference Information

Schematic Reference

Exterior Lamps Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Exterior Lighting Systems Description and Operation

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Ignition ON, perform the Reverse Lamps Relay test. The reverse lamp should be ON/OFF.

Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector at the B16 Reverse Lamp Switch.
  2. Test for less than 5 Ω between the ground circuit harness connector terminal B and ground.
  3. If greater than the specified value, test the ground circuit for an open/high resistance.
  4. Disconnect the X2 harness connector at the K20 Engine Control Module.
  5. Ignition ON, test for less than 0.3 V at the B16 Reversing Light Switch signal circuit harness connector terminal A and ground.
  6. If greater then the specified value, test the signal circuit for a short to voltage.
  7. Ignition OFF, test for infinite resistance between the B16 Reverse Lamp Switch signal circuit harness connector A and ground.
  8. If lower then the specified value, test the signal circuit for a short to ground.
  9. Connect the harness connector at the B16 Reverse Lamp Switch.
  10. Reverse gear engaged, test for less than 5.0 Ω between the K20 Engine Control Module X2 harness connector terminal listed below and ground:
  11. • Terminal 16 with LNP
    • Terminal 87 with 2H0
    • Terminal 23 with LAF
    If greater then the specified value, test the signal circuit for an open/high resistance. If the circuit test normal, test or replace the B16 Reverse Lamp Switch.
  12. Reverse gear disengaged, test for infinite resistance between the K20 Engine Control Module X2 harness connector terminal listed below and ground:
  13. • Terminal 16 with LNP
    • Terminal 87 with 2H0
    • Terminal 23 with LAF
    If lower then the specified value, test or replace the B16 Backup Lamp Switch.
  14. If all the circuits test normal, replace the K20 Engine Control Module.

Component Testing

Static Test

  1. Ignition OFF, disconnect the harness connector at the B16 Reverse Lamp Switch. Reverse gear engaged, test for less than 5.0 Ω at the B16 Reversing Light Switch terminal A and terminal B.
  2. If greater than the specified value replace the B16 Reverse Lamp Switch.
  3. Reversing gear disengaged, test for infinite resistance at the B16 Reverse Lamp Switch terminal A and terminal B.
  4. If less than the specified value replace the B16 Reverse Lamp Switch.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Tail Lamp Replacement
    • Control Module References for BCM replacement, setup and programming
   


© Copyright Chevrolet. All rights reserved
   


© Copyright Chevrolet. All rights reserved