2010 Cadillac Truck Escalade RWD V8-6.0L Hybrid Page 3249

2010 Cadillac Truck Escalade RWD V8-6.0L Hybrid Page 3249

Repair Instructions

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

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

Procedures/Wiring Repairs/GMLAN Wiring Repairs)

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

programming

U0422

DTC U0100-U02FF (with HP2)

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.

DTC Descriptor

Refer to Control Module U Code List (See: Diagnostic Trouble Code Descriptions/Control Module U Code List).

Diagnostic Fault Information

Circuit/System Description

The serial data circuit is the means by which the control modules in the vehicle communicate with each other. Once the scan tool is connected to the

serial data circuit through the DLC, the scan tool can be used to monitor each control module for diagnostic purposes and to check for diagnostic

trouble codes (DTCs). When the ignition switch is in RUN, each control module communicating on the serial data circuit sends a state of health

(SOH) message to ensure that the control module is operating properly. When a control module stops communicating on the serial data circuit, for

example if the module loses power or ground, the SOH message it normally sends on the serial data circuit disappears. Other control modules on

the serial data circuit, which expect to receive that SOH message, detect its absence; those control modules in turn set a DTC associated with the

loss of SOH of the non-communicating control module. The DTC is unique to the control module which is not communicating and one or more

control modules may set the same exact code. A loss of serial data communications DTC does not represent a failure of the control modules that

contain the stored code.

Conditions for Running the DTC

The system voltage is between 9-16 V.

Conditions for Setting the DTC

A supervised periodic message that includes the transmitter module availability has not been received.

Action Taken When the DTC Sets

* Specific subsystems will not function.

* DTC U0100 in the TCM will cause the transmission to go into default gears.

* Both DTC U0100 in the TCM and DTC U0101 in the ECM will cause the malfunction indicator lamp (MIL) to illuminate.