2010 Cadillac Truck SRX FWD V6-3.0L Page 2154
* The battery positive voltage input circuits
* The battery positive voltage output circuits
* The ignition voltage input circuits
* The ignition voltage output circuits
* The switched battery positive voltage supply circuits
瀚慖f the test lamp does not illuminate, test the circuit for an open/high resistance. If the circuit fuse is open, test the circuit for a short to
ground. If the circuit tests normal, replace the applicable control module.
5. Ignition OFF, test for less than 5 ohm between the non-communicating modules GMLAN serial data circuits and the module reporting DTC
U0002.
瀚慖f greater than the specified range, test the circuit for an open/high resistance.
6. If all circuits test normal, replace the applicable control module.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* Control Module References (See: Testing and Inspection/Programming and Relearning) for module replacement, setup, and programming
* GMLAN Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic
Procedures/Wiring Repairs/GMLAN Wiring Repairs)
U02FF
DTC U0100-U02FF
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 data link connector (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 control 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
