2010 Cadillac Truck Escalade EXT AWD V8-6.2L Page 2854
* Supply voltage to the modules are in the normal operating range.
* The ignition switch in any position other than START.
Conditions for Setting the DTC
The module setting the DTC has attempted to establish communications on the PTLAN serial data circuits more than 3 times.
Action Taken When the DTCs Sets
* The module suspends all message transmission.
* The MIL and battery indicators will illuminate, along with several DIC messages.
* The vehicle may continue to run for several minutes, then will stall and not start.
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, without a repeat of the malfunction.
Circuit/System Verification
Verify that U0074 is not set.
If the DTC is set, refer toDTC U0074 (See: U Code Charts/U0074)
U0181
DTC U0100-U02FF (without 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
