2010 Cadillac Truck Escalade RWD V8-6.0L Hybrid Page 3188

2010 Cadillac Truck Escalade RWD V8-6.0L Hybrid Page 3188

Circuit/System Verification

Verify that DTC U1814, U2099, B1428, B1370, B1380, B1440, or B1441 is not set.

If any of the DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle (See: Diagnostic Trouble Code Descriptions/Diagnostic

Trouble Code (DTC) List - Vehicle).

Circuit/System Testing

Danger: Always perform the High Voltage Disabling procedure prior to servicing any High Voltage component or connection. Personal

Protection Equipment (PPE) and proper procedures must be followed.

The High Voltage Disabling procedure will perform the following tasks:

* Identify how to disable high voltage.

* Identify how to test for the presence of high voltage.

* Identify condition under which high voltage is always present and personal protection equipment (PPE) and proper procedures must

be followed.

Before working on any high voltage system, be sure to wear the following Personal Protection Equipment:

* Safety glasses with appropriate side shields when within 50 feet of the vehicle, either indoors or outdoors.

* Certified and up-to-date Class "0" Insulation gloves rated at 1000V with leather protectors.

- Visually and functionally inspect the gloves before use.

- Wear the Insulation gloves at all times when working with the high voltage battery assembly, whether the system is energized or

not.

Failure to follow the procedures exactly as written may result in serious injury or death.

Note: Use the schematic to identify the following:

* Control modules the vehicle is equipped with

* Control module locations on the low and high speed GMLAN serial data circuits

* The control modules B+, ignition, ground, communication enable and serial data circuit terminals

1. Determine the control module that is not communicating. Refer to Control Module U Code List (See: Diagnostic Trouble Code

Descriptions/Control Module U Code List).

2. Using the Hybrid High Voltage Module Chart below, verify that the non-communicating control module is not a high voltage module. If the

control module is a high voltage module, perform the High Voltage Disabling (See: Hybrid Drive Systems/Battery System, Hybrid

Drive/Testing and Inspection/Initial Inspection and Diagnostic Overview/High Voltage Disabling) procedure before proceeding with this

diagnostic.

3. If high voltage disabling is required, reconnect the 12 V battery after performing the high voltage disabling procedure.

4. Ignition OFF, disconnect the harness connector of the control module that is not communicating.

5. Test for less than 10 ohm between each ground circuit terminal and ground.

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

6. If equipped, verify that a test lamp illuminates between each B+ circuit terminal 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 fuse is open, test the

control circuits of the control module for a short to ground. If the circuits test normal, replace the control module.

7. If equipped, ignition ON, verify that a test lamp illuminates between each ignition circuit terminal and ground.

瀚慖f the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance. If the circuit fuse is open, test

the control circuits of the control module for a short to ground. If the circuits test normal, replace the control module.

Note: Only the high speed GMLAN modules have a serial data communication enable circuit OR an accessory wakeup serial data circuit,

and the BCM is the output for these circuits. Refer to the module schematics to identify which modules have these circuits.

8. If equipped, ignition ON, verify that a test lamp illuminates between the communication enable circuit terminal OR the accessory wakeup

circuit terminal and ground.

瀚慖f the test lamp does not illuminate, test the circuit for an open/high resistance. If the circuits test normal, replace the BCM.