Diagnostic Instructions

DTC Descriptors

DTC U1500 01: Inter-Device Dedicated Bus 1 Short to Battery

DTC U1500 02: Inter-Device Dedicated Bus 1 Short to Ground

DTC U1511 00: Inter-device Dedicated Bus Lost Communication With Device 1

DTC U1512 00: Inter-device Dedicated Bus Lost Communication With Device 2

Diagnostic Fault Information

Circuit	Short to Ground	Open/High Resistance	Short to Voltage
B+ - Window Motor	U1511, U1512	U1511, U1512	--
Ignition - Electronic Compass Module	U1511	U1511	--
Serial Data - Electronic Compass Module, Terminal 3	U1511	U1511	U1511
Serial Data- Driver Window Motor, Terminal 5	U1500 02	U1511	U1500 01
Serial Data - Passenger Window Motor, Terminal 5	U1500 02	U1512	U1500 01
Ground - Electronic Compass Module	--	U1511	--
Ground - Window Motor	--	U1511¹, U1512¹	--
¹ Either or both DTC may set depending on the location of the open/high resistance.

Circuit/System Description

The driver door module (DDM) and the front passenger door module (FPDM) communicate with window regulator motors on the local interconnect network bus 1 and the local interconnect network bus 2 circuits respectively. When the driver power window switch is activated to a desired position, the DDM examines the request and checks for messages from other vehicle control modules prohibiting window movement. If no prohibitive messages have been received, the DDM will send a LIN serial data message to the driver door window motor to move the window to the desired position.

When the DDM receives a request to operate one of the right side passenger windows from the driver master control, a GMLAN serial data message is sent to the PDM. The PDM examines the request and checks for messages from other vehicle control modules prohibiting the window movement. If no prohibitive messages have been received, the PDM will send a LIN serial data message to the appropriate window motor to move the window as requested.

The DDM and PDM supply their respective rear power window switches with a 12-volt reference and signal circuit. The rear power window switches contain separate resistors for each switch position. When a rear power window switch is activated, the associated door control module interprets the signal and checks for messages from other vehicle control modules prohibiting the window movement. If no prohibitive messages have been received, the door control module sends a LIN serial data message to the appropriate power window motor commanding the requested window position.

The driver information center (DIC) displays the compass based on serial data message from the BCM. The compass module communicates with the body control module (BCM) through a bi-directional data circuit (LIN). The instrument panel cluster (IPC) receives compass information from the BCM via the serial data circuit.

Conditions for Running the DTC

The system voltage is between 9-16 volts.

Conditions for Setting the DTC

U1500 01

When there is a short to voltage in the local interconnect network bus circuit.

U1500 02

When there is a short to ground in the local interconnect network bus circuit.

U1511, U1512

The DTC will set when there is an open/high resistance in the local interconnect network bus circuit, or an open in the voltage or ground circuits of the motor or module.

Action Taken When the DTC Sets

U1500

The individual LIN bus will be inoperative, disabling all windows on one side of the vehicle.

U1511

U1512

No window on the specific side of the vehicle will operate if the open is before the first splice from the door module, and both DTC U1511 and U1512 should set. If open after the first splice, the individual window will be inoperative and a single DTC should set.

Conditions for Clearing the DTC

Diagnostic Aids

Reference Information

Schematic Reference

Data Communication Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Data Link Communications Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for Scan Tool Information

Circuit/System Verification

1. With a scan tool, verify that DTC U1511 is not set in the BCM.

⇒	If DTC U1511 is set in the BCM, perform the Compass Malfunction Test.

2. Perform the Window Malfunction Test

Circuit/System Testing

Compass Malfunction Test

1. Ignition OFF, disconnect the harness connector at the electronic compass module.
2. Ignition OFF, test for less than 5.0 ohm between the ground circuit terminal 2 and ground.

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

3. Ignition ON, verify a test lamp illuminates between the ignition voltage circuit terminal 1 and ground.

⇒	If the test lamp does not illuminate, test the ignition voltage circuit for a short to ground or an open/high resistance.

4. Test for 6.0-7.0 volts between the LIN circuit terminal 3 and ground.

⇒	If greater than the specified range, test the LIN circuit for a short to voltage. If the circuit tests normal, replace the BCM.

⇒	If less than the specified range, test the LIN circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.

5. If all circuits test normal, replace the electronic compass module.

Window Malfunction Test

1. Ignition OFF, disconnect the harness connector at the appropriate window motor.
2. Ignition OFF, test for less than 2.0 ohm between the ground circuit terminal 4 and ground.

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

3. Ignition ON, verify a test lamp illuminates between the B+ circuit terminal 3 and ground.

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

4. Test for 6.0-7.0 volts between the LIN circuit terminal 5 and ground.

⇒	If greater than the specified range, test the LIN circuit for a short to voltage. If the circuit tests normal, replace the applicable door module.

⇒	If less than the specified range, test the LIN circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the applicable door module.

5. Ignition OFF, reconnect the harness connector at the window motor.
6. Ignition ON, observe the appropriate scan tool Window Motor Fault Status parameter while raising and lower the window. The parameter should read No Fault.

⇒	If the parameter displays Not Normalized, refer to Window Regulator Motor Programming and Setup.

⇒	If the parameter reads Motor Fault, Hall Fault, Memory Fault, LIN Fault, Anti-Trap Fault or Thermo Active, test or replace the appropriate power window motor.

7. If all circuits test normal, replace the appropriate door module.

Repair Instructions

Important: Each window regulator motor or front window and door lock switch, if replaced needs to be setup for proper operation.

Perform the Diagnostic Repair Verification after completing the repair.