Conditions for Running the DTC
* The system voltage is between 9-16 volts.
* The vehicle power mode master requires serial data communication to occur from this specific module.
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
The modules is never signaled, therefore the specific subsystems will not function.
Conditions for Clearing the DTC
* A current DTC clears when the malfunction is no longer present.
* A history DTC clears when the module ignition cycle counter reaches the reset threshold of 50, without a repeat of the malfunction.
Diagnostic Aids
* When testing circuits to the SDGM access can be accomplished by removing the instrument panel center trim panel. Note that this procedure
does not allow removal of the SDGM, only access to the connector. Refer to Instrument Panel Center Trim Panel Replacement (Cadillac) (
See: Body and Frame/Interior Moulding / Trim/Dashboard / Instrument Panel/Service and Repair/Instrument Panel Center Trim Panel
Replacement (Cadillac))Instrument Panel Center Trim Panel Replacement (Except Cadillac) (See: Body and Frame/Interior Moulding /
Trim/Dashboard / Instrument Panel/Service and Repair/Instrument Panel Center Trim Panel Replacement (Except Cadillac)).
* If the ECM is inoperative due to an open in the voltage or ground circuits then DTC U0100 will be set current in the power steering control
module (PSCM).
* Different DTCs may set in different modules along with this DTC depending on where the fault occurs and the vehicle operating conditions
when the fault occurs.
Reference Information
Schematic Reference
* Data Communication Schematics (See: Powertrain Management/Computers and Control Systems/Information Bus/Diagrams/Electrical
Diagrams)
* Control Module References (See: Testing and Inspection/Programming and Relearning)
Connector End View Reference
Component Connector End Views (See: Diagrams/Connector Views)
Description and Operation
Data Link Communications Description and Operation (See: Powertrain Management/Computers and Control Systems/Information
Bus/Description and Operation)
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)
Circuit/System Verification
Verify the following DTCs are not set in the modules as follows:
* PSCM - U0100
* SDGM - U189A
If any listed DTC is present, refer to Diagnostic Trouble Code (DTC) List - Vehicle (See: Diagnostic Trouble Code Descriptions/Diagnostic
Trouble Code (DTC) List - Vehicle) to diagnose that DTC prior to this diagnostic.
Circuit/System Testing
1. Ignition OFF, disconnect harness connector X1 of the APM and the EBCM.
2. Test for less than 1.0 ohm between the APM and the EBCM on the following circuit terminals.
