2010 Cadillac Truck Escalade RWD V8-6.0L Hybrid Page 3004

2010 Cadillac Truck Escalade RWD V8-6.0L Hybrid Page 3004

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.

Diagnostic Aids

* Sometimes, while diagnosing a specific customer concern or after a repair, you may notice a history U-code present. However, there is no

associated "current" or "active" status. Loss-of- communication U-codes such as these can set for a variety of reasons. Many times, they're

transparent to the vehicle operator and technician, and/or have no associated symptoms. Eventually, they will erase themselves automatically

after a number of fault-free ignition cycles. This condition would most likely be attributed to one of these scenarios:

- A control module on the data communication circuit was disconnected while the communication circuit is awake.

- Power to one or more modules was interrupted during diagnosis

- A low battery condition was present, so some control modules stop communicating when battery voltage drops below a certain threshold.

- Battery power was restored to the vehicle and control modules on the communication circuit did not all re-initialize at the same time.

- If a loss-of-communication U-code appears in history for no apparent reason, it is most likely associated with one of the scenarios above.

These are all temporary conditions and should never be interpreted as an intermittent fault, causing you to replace a part.

* Do not replace a control module reporting a U code. The U code identifies which control module needs to be diagnosed for a communication

issue.

* Communication may be available between the BCM and the scan tool with the Powertrain High Speed GMLAN serial data system

inoperative. This condition is due to the BCM using both the high and low speed GMLAN systems.

* The engine will not start when there is a total malfunction of the Powertrain High Speed GMLAN serial data bus.

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 Testing

Note: Each control module may need to be disconnected to isolate a circuit fault. Use the schematic to identify the following:

* Control modules the vehicle is equipped with

* Powertrain High Speed GMLAN serial data circuit terminating resistors

* Control module locations on the Powertrain High Speed GMLAN serial data circuits

* Each control module's Powertrain High Speed GMLAN serial data circuit terminals