2010 Cadillac Truck SRX AWD V6-2.8L Turbo Page 2049

2010 Cadillac Truck SRX AWD V6-2.8L Turbo Page 2049

* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure

Instructions) provides an overview of each diagnostic category.

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 body control module (BCM) activates the high speed GMLAN serial data wake up and the accessory wake up serial data circuits by applying

voltage when the ignition key is in ACC, ON or START. The high speed GMLAN serial data wake up circuit wakes up the electronic brake control

module (EBCM) for bus communication and the accessory wake up serial data circuit wakes up the engine control module (ECM) and transmission

control module (TCM).

Conditions for Running the DTC

* The system voltage is between 9-16 volts.

* The vehicle power mode requires serial data communication to occur.

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 module uses a default value for the missing parameters.

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

* Use the DTC Descriptor list above to determine the module which is not communicating.

* If there are multiple non-communicating modules choose the one closest to the data link connector (DLC).

* Use Data Link References (See: Powertrain Management/Computers and Control Systems/Information Bus/Testing and Inspection/Initial

Inspection and Diagnostic Overview) to determine if the module uses high or low speed GMLAN serial data communications

* Some modules may not have internal protection for specific voltage outputs and may open a battery positive voltage or ignition voltage

source fuse. If a voltage input fuse is open and no short is found in that circuit, ensure that no module output voltage circuit is shorted to

ground before replacing the module.

* This diagnostic can be used for any module that should communicate with high or low speed GMLAN serial data providing the vehicle is

equipped with the option that uses that module.

Reference Information

* 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/Connector End Views By Name)

Description and Operation