2010 Cadillac Truck SRX AWD V6-3.0L Page 2161

2010 Cadillac Truck SRX AWD V6-3.0L Page 2161

Conditions for Setting the DTC

The control module setting the DTC has attempted to establish communications on the serial data circuits more than 3 times in 5 seconds.

Action Taken When the DTCs Sets

* The control module suspends all message transmission.

* The control module uses default values for all parameters received on the serial data circuits.

* In the TCM, DTC U0073 will cause the transmission to go into default gears.

* In the ECM and TCM, DTC U0073 will cause the malfunction indicator lamp (MIL) to illuminate.

* The control module inhibits the setting of all other communication DTCs.

Conditions for Clearing the DTC

* The ECM/TCM modules turn OFF the MIL after 4 consecutive ignition cycles that the diagnostic runs and does not fail.

* 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.

Circuit/System Verification

1. Refer to Data Link References (See: Powertrain Management/Computers and Control Systems/Information Bus/Testing and

Inspection/Initial Inspection and Diagnostic Overview) to determine which serial data system is used for a specific control module.

2. This DTC cannot be retrieved with a current status. Diagnosis is accomplished using the symptom. Refer to Symptoms - Data

Communications (See: Powertrain Management/Computers and Control Systems/Information Bus/Testing and Inspection/Symptom Related

Diagnostic Procedures/Symptoms - Data Communications).

U0074

DTC U0074

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 U0074 00

- Control Module Communication Bus B Off

Diagnostic Fault Information

Circuit/System Description

Control modules connected to the mid speed or chassis high speed GMLAN serial data circuits monitor for serial data communications during