2010 Cadillac Truck Escalade/ESV RWD V8-6.2L Page 2742
U182A
DTC U182A
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
DTC U182A 00
- Lost Communication With Accessory Power Module
Diagnostic Fault Information
Circuit/System Description
Modules connected to the high and low speed GMLAN serial data circuits monitor for serial data communications during normal vehicle operation.
Operating information and commands are exchanged among the modules. The modules have prerecorded information about what messages are
needed to be exchanged on the serial data circuits, for each virtual network. The messages are supervised and also, some periodic messages are
used by the receiver module as an availability indication of the transmitter module. Each message contains the identification number of the
transmitter module.
The serial data gateway module (SDGM) energizes the wake up signal to activate the accessory DC power control module (APM) when
communication is needed. The SDGM monitors the signal circuit for faults.
Conditions for Running the DTC
* The system voltage is between 9-16 V.
* The ignition in RUN.
Conditions for Setting the DTC
* The APM wake up signal is open.
* The APM does not receive battery voltage.
* The powertrain serial data circuits between the SDGM and the APM are open.
Action Taken When the DTC Sets
The modules is never signaled, therefore the specific subsystems may not function. Depending on the fault, the MIL, battery indicator may
illuminate and several DIC messages may be present.
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)).
* Different DTCs may set in different modules along with this DTC depending on where the fault occurs and the vehicle operating conditions
