2010 Cadillac Truck Escalade EXT AWD V8-6.2L Page 327

2010 Cadillac Truck Escalade EXT AWD V8-6.2L Page 327

Diagnostic Aids

* A TRUE B+ has enough current to light a test light.

* A DIAGNOSTIC B+ is a low current circuit that DOES NOT have enough current to light a test light.

* A short to ground on the AWD indicator control circuit will cause the AWD indicator to remain ON at all times.

* An open or high resistance on the AWD indicator control circuit will cause the AWD indicator to be inoperative during the 2 second bulb

inspection.

* An open in the indicator dimming control circuit will cause the 2 High, AWD, 4 High and 4 Low mode indicators to be inoperative during

the 2 second bulb inspection.

* The EL-49741 - harness is a good source for 9 V.

* The EL-49742 - harness is a good source for B+ and ground.

* With key REMOVED - opening a door puts a true B+ on the indicator dimming control circuit, TCSCS X1 pin 4. Other possible voltages are

listed below:

- Door open, key removed - indicator dimming control circuit voltage = true B+.

- Door open, key in, key OFF - indicator dimming control circuit voltage = true B+.

- Door open, key ON, engine OFF - indicator dimming control circuit voltage = diagnostic B+.

- All doors closed, key OFF - indicator dimming control circuit voltage = B+ (high current - enough to light a test light).

- All doors closed, key ON, engine OFF - indicator dimming control circuit voltage = diagnostic B+.

- Key ON, engine OFF. Place a shop light on the DRL sensor. When the DRL sensor commands the headlights OFF, the indicator dimming

control circuit voltage, TCSCS X1 pin 4, will go from a diagnostic B+ to a true B+.

Reference Information

Schematic Reference

Transfer Case Control Schematics (See: Transmission and Drivetrain/Transfer Case/Diagrams/Electrical Diagrams/MP 3023/3024-NQH -

Transfer Case)

Connector End View Reference

Component Connector End Views (See: Diagrams/Connector Views)

Electrical Information Reference

* Circuit Testing (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic Procedures/Circuit

Testing/Circuit Testing)

* Connector Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic

Procedures/Connector Repairs/Connector Repairs)

* Testing for Intermittent Conditions and Poor Connections (See: Testing and Inspection/Component Tests and General Diagnostics/General

Electrical Diagnostic Procedures/Circuit Testing/Testing for Intermittent Conditions and Poor Connections)

* Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic Procedures/Wiring

Repairs/Wiring Repairs)

Scan Tool Reference

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

Special Tools

* EL-49741 - 9 V+ Power Source Harness

* EL-49742 - Battery Voltage B+ and Ground Source Harness

* J 35616 - GM-Approved Terminal Test Kit

Circuit/System Verification

Key ON, engine OFF. The TCCM runs a 2 second bulb test on all indicators of the TCSCS at key ON.

Circuit/System Testing

Note: When test probing harness terminals, it is imperative to use the proper test probe from the most current version of the J 35616 - kit.

Use of an improper test probe may deform the terminal, resulting in intermittent open conditions.

1. Remove key. Disconnect the X1 connector at the transfer case shift control switch (TCSCS).

2. Door Open, key ON, engine OFF.

3. Using the L-BU probe J 35616-64B, test for a diagnostic B+ (+0.0/-1.0 V) between the indicator dimming control circuit, TCSCS X1 pin 4

and a good ground, such as the ground terminal of the EL-49742 - harness, black terminal.

瀚慖f the voltage is less than the specified range, test the affected circuit for an open/high resistance, short to ground, or short to voltage. If

all circuits and connections test normal, test the body control module (BCM) for proper operation.

4. Using the L-BU probe J 35616-64B, test for a diagnostic B+ (+0.0/-1.0 V) between the indicator dimming control circuit, TCSCS X1 pin 4

and the AWD indicator control circuit, TSCSC X1 pin 7.