2010 Cadillac Truck SRX FWD V6-3.0L Page 2173

2010 Cadillac Truck SRX FWD V6-3.0L Page 2173

* 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).

Circuit/System Description

The serial data is transmitted over a Local Interconnect Network (LIN) single wire network circuit bus between a master control module and other

control modules within a particular subsystem. If serial data communication is lost between any of the control modules on the LIN bus network, a

no communication code against the non-communicating control module will be set. A master control module is the one that reports the non

communication code. Note: a loss of serial data communications DTC does not represent a failure of the master control module that set it.

Diagnostic Aids

* A control module may have a U-code stored in history that does not require any repairs. Issues with late or corrupted messages between

control modules can be temporary with no apparent symptom or complaint; this does not mean the control module is faulty. Do not replace a

control module based only on a history U-code.

* 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 will be available between the master control module and the scan tool if there is a loss of communications with any of the

other control modules on the LIN bus network.

* An open in the LIN bus serial data circuit between the splice pack and a module will only affect that specific module. This type of failure will

set a loss of communication DTC for each control module affected and the other control modules will still communicate.

Reference Information

Schematic Reference

Data Communication Schematics (See: Powertrain Management/Computers and Control Systems/Information Bus/Diagrams/Electrical Diagrams)

Connector End View Reference

Component Connector End Views (See: Diagrams/Connector Views/Connector End Views By Name)

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:

* Use the schematic to identify the following:

- Control modules and LIN devices the vehicle is equipped with

- Control module and LIN device locations on the serial data circuit

- The control module serial data circuit terminals and LIN device B+, ignition, ground, and serial data circuit terminals

* Use the Control Module U-Code list to determine which control module is not communicating with the master control module. Refer to

Control Module U Code List (See: Diagnostic Trouble Code Descriptions/Control Module U Code List).

* A loss of serial data communications DTC does not represent a failure of the master control module that set it.

1. Ignition OFF, disconnect the harness connector at a LIN device that is not communicating.

2. Test for less than 5 ohm between each ground circuit terminal and ground.

瀚慖f greater than the specified range, test the ground circuit for an open/high resistance.

3. If equipped, verify that a test lamp illuminates between each B+ circuit terminal and ground.

瀚慖f the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit fuse is open, test the

control circuits of the LIN device for a short to ground. If the circuits test normal, replace the LIN device.