2010 Cadillac Truck SRX AWD V6-2.8L Turbo Page 2034
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 control module for a short to ground. If the circuits test normal, replace the control module.
4. If equipped, ignition ON, verify that a test lamp illuminates between each ignition circuit terminal and ground.
瀚慖f the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance. If the circuit fuse is open, test
the control circuits of the control module for a short to ground. If the circuits test normal, replace the control module.
Note: Only the high speed GMLAN modules have a serial data communication enable circuit OR an accessory wake-up serial data circuit,
and the BCM is the output for these circuits. Refer to the control module schematics to identify which modules have these circuits.
5. If equipped, ignition ON, verify that a test lamp illuminates between the communication enable circuit terminal OR the accessory wake-up
circuit terminal and ground.
瀚慖f the test lamp does not illuminate, test the entire circuit, including the B+ circuit to the BCM, for an open/high resistance or short to
ground. If the circuits test normal, replace the BCM.
6. Ignition OFF for 60 seconds, test for less than 5 ohm between the serial data circuit terminals and the appropriate DLC terminal listed below:
* Class 2 serial data circuit terminal 2
* Low speed GMLAN serial data terminal 1
* High speed GMLAN serial data terminal 6 or 14
瀚慖f greater than the specified range, test the serial data circuit for an open/high resistance between the non communicating control module
and a module setting the DTC or a serial data splice pack.
7. If all circuits test normal, replace the control module that is not communicating.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* GMLAN Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic
Procedures/Wiring Repairs/GMLAN Wiring Repairs)
* Control Module References (See: Testing and Inspection/Programming and Relearning) for control module replacement, setup, and
programming
U0300
DTC U0300-U0336
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 Descriptors
DTC U0301 00
- Software Incompatibility with Engine Control Module
DTC U0302 00
- Software Incompatibility with Transmission Control Module
DTC U0315 00
- Software Incompatibility with Electronic Brake Control Module
Circuit/System Description
Some control modules must be configured with specific software, serial numbers, vehicle options, or other information. If a control module was not
properly configured after installation that module may set the appropriate U Code. No external circuit diagnosis is involved.
Conditions for Running the DTC
