2010 Cadillac Truck Escalade EXT AWD V8-6.2L Page 658

2010 Cadillac Truck Escalade EXT AWD V8-6.2L Page 658

Control Module References (See: Testing and Inspection/Programming and Relearning) for scan tool information

Circuit/System Testing

1. Ignition OFF, disconnect the fog lamp relay.

2. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal 87 and ground.

瀚慖f the test lamp illuminates, test the control circuit for a short to voltage.

3. Verify that a test lamp illuminates between the B+ circuit terminal 30 and ground.

瀚慖f the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the

B+ circuit fuse is open, test the control circuit terminal 87 for a short to ground. If the circuit tests normal, test or replace the fog lamp

relay.

4. Verify that a test lamp illuminates between the B+ circuit terminal 85 and ground.

瀚慖f the test lamp does not illuminate, test the B+ circuit for an open/high resistance.

5. Disconnect the harness connector at the appropriate fog lamp front.

6. Test for less than 5 ohm between the fog lamp front ground circuit terminal B and ground

瀚慖f greater than the specified range, test the ground circuit for an open/high resistance.

7. Connect the harness connector at the fog lamp front.

8. Connect a 15 A fused jumper wire between the B+ circuit terminal 30 and the control circuit terminal 87. Verify the fog lamp front is

activated.

瀚慖f the fog lamp front does not activate and the circuit fuse is good, test the control circuit for an open/high resistance. If the circuit tests

normal, test or replace the fog lamp front.

瀚慖f the fog lamp front does not activate and the circuit fuse is open, test the control circuit for a short to ground. If the circuit tests normal,

test or replace the fog lamp front.

9. Connect a test lamp between the B+ circuit terminal 85 and the control circuit terminal 86.

10. Command the Fog Lamps ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded

states.

瀚慖f the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM.

瀚慖f the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace

the BCM.

11. If all circuits test normal, test or replace the fog lamp relay.

Repair Instructions

Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.

* Relay Replacement (Attached to Wire Harness) (See: Power and Ground Distribution/Power Distribution Relay/Service and Repair/Relay

Replacement (Attached to Wire Harness))Relay Replacement (Within an Electrical Center) (See: Power and Ground Distribution/Power

Distribution Relay/Service and Repair/Relay Replacement (Within an Electrical Center))

* Front Fog Lamp Replacement (Tahoe, Avalanche) (See: Lighting and Horns/Fog/Driving Lamp/Service and Repair/Removal and

Replacement/Front Fog Lamp Replacement (Tahoe, Avalanche))Front Fog Lamp Replacement (Yukon) (See: Lighting and

Horns/Fog/Driving Lamp/Service and Repair/Removal and Replacement/Front Fog Lamp Replacement (Yukon))Front Fog Lamp

Replacement (PLATINUM) (See: Lighting and Horns/Fog/Driving Lamp/Service and Repair/Removal and Replacement/Front Fog Lamp

Replacement (Platinum))

* Control Module References (See: Testing and Inspection/Programming and Relearning) for BCM replacement, setup, and programming

B2540

DTC B2540

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System

Check - Vehicle) prior to using this diagnostic procedure.

* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an

overview of the diagnostic approach.

* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure

Instructions) provides an overview of each diagnostic category.