Diagnostic Routine AL

Diagnostic Routine AL

Diagnostic Overview

The Trailer Lamps Are On Continuously

Refer to Wiring Diagram Set 11 for schematic and connector information Electrical Diagrams.

Refer to Wiring Diagram Set 95 for schematic and connector information Electrical Diagrams.

Normal Operation and Fault Conditions

REFER to Trailer Stop-Turn Lamps .

REFER to Trailer Parking Lamps .

REFER to Trailer Reversing Lamps .

DTC Fault Trigger Conditions






Visual Inspection and Diagnostic Pre-checks

- Inspect the vehicle exterior lamps for correct operation.

- Inspect the trailer tow connector for damage.

Pinpoint Test

NOTE: Before beginning diagnostics, visually inspect the trailer tow connector mounted on the bumper for signs of corrosion or damage. Repair or install a new trailer tow connector as required.

1. CHECK FOR VOLTAGE AT THE TRAILER TOW CONNECTOR

1. Ignition ON.

2. For a trailer tow 4-pin connector, measure:





3. For a trailer tow 7-pin connector, measure:





Is any voltage present?








2. CHECK THE RELAY OUTPUT CIRCUIT TO THE TRAILER TOW CONNECTOR FOR A SHORT TO VOLTAGE

1. Ignition OFF.

2. Disconnect: Suspect Trailer Tow Relay.

3. Ignition ON.

4. For a trailer tow 4-pin connector, measure:





5. For a trailer tow 7-pin connector, measure:





Is any voltage present?








3. CHECK FOR VOLTAGE TO THE TRAILER TOW RELAY COIL

1. For the trailer tow left stop/turn lamp, measure:





2. For the trailer tow right stop/turn lamp, measure:





Is any voltage present?








4. CHECK THE BCM (Body Control Module) OUTPUT CIRCUIT FOR A SHORT TO VOLTAGE

1. Ignition OFF.

2. Disconnect: BCM (Body Control Module) C2280D.

3. Ignition ON.

4. For the trailer tow left stop/turn lamp, measure:





5. For the trailer tow right stop/turn lamp, measure:





Is any voltage present?








5. CHECK FOR CORRECT BCM (Body Control Module) OPERATION

1. Disconnect and inspect all BCM (Body Control Module) connectors.

2. Repair:

- corrosion (install new connector or terminals- clean module pins)
- damaged or bent pins- install new terminals/pins
- pushed-out pins- install new pins as necessary

3. Reconnect the BCM (Body Control Module) connectors. Make sure they seat and latch correctly.

4. Operate the system and determine if the concern is still present.

Is the concern still present?