For 1990-2009 cars

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• | Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• | Diagnostic Procedure Instructions provides an overview of each diagnostic category.

### 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 | Signal Performance
--- | --- | --- | --- | ---
Linear Interconnect Network Bus 1 | U1500 02 | U1511 00, U1512 00* | U1500 01 | --
Linear Interconnect Network Bus 2 | U1500 02 | U1511 00, U1512 00* | U1500 01 | --
Battery Positive Voltage (front window motor) | U1511 00** | U1511 00 | -- | --
Battery Positive Voltage (rear window motor) | U1512 00** | U1512 00 | -- | --
Ground (front window motor) | -- | U1511 00 | -- | --
Ground (rear window motor) | -- | U1512 00 | -- | --
* An open between a door module and the splice will cause both DTCs, and an open between the splice and the window motor will cause only 1 DTC. ** A short to ground on B+ to any window motor will cause all windows to be inoperative due the use of a single circuit breaker for all window motors. DTC U1511 and U1512 will be set in both the driver and passenger door modules.

### 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. The DDM LIN bus is connected to all window regulator motors on its side of the vehicle, while the FPDM LIN bus is connected to the other window regulator motors. Communication on this network is only between the door modules and the window regulator motors. The window regulator motors are in effect modules. The window regulator motors do not communicate on any other data bus; therefore the door modules, which also communicate on the low speed GMLAN serial data bus will perform all communication with each other. If the driver depresses any passenger side window switch on the driver window switch the DDM communicates the information to the FPDM for operation. These DTCs will set in the DDM for driver side concerns or the FPDM for passenger side concerns.

### Conditions for Running the DTC

The system voltage is between 9-16 volts.

### Conditions for Setting the DTC

#### U1511 00

• | The local interconnect network bus circuit of the front window motor has an open/high resistance.

• | The B+ circuit of the front window motor is open or shorted to ground.

• | The ground circuit of the front window motor is open.

#### U1512 00

• | The local interconnect network bus circuit of the rear window motor has an open/high resistance.

• | The B+ circuit of the rear window motor is open or shorted to ground.

• | The ground circuit of the rear window motor is open.

#### U1500 02

The local interconnect network bus circuit is a shorted to ground.

#### U1500 01

The local interconnect network bus circuit is a shorted to voltage.

### Action Taken When the DTC Sets

#### U1511 00

The front window will operate.

#### U1512 00

The rear window will operate.

#### U1500

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

### Conditions for Clearing the DTC

• | The current DTC will clear when the malfunction is no longer present.

• | A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.

### Diagnostic Aids

• | Both DTC U1511 and U1512 will set if an open/high resistance in the local interconnect network bus circuit is between the door module and the first splice.

• | Only 1 DTC (U1511 or U1512) will set if an open/high resistance in the local interconnect network bus circuit is between the splice and the window motor.

### Reference Information

#### Schematic Reference

Door Control Module Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

Data Link Communications Description and Operation

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

Control Module References for scan tool information

### Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the appropriate front window motor.
2. Test for less than 2.0 ohms 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 1 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 5.5-7.0 volts between the LIN circuit terminal 6 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, command the appropriate power window UP/DOWN with a scan tool. The window should go UP/DOWN.

⇒ | If the window fails to go UP/DOWN, check the serial data circuit terminal 6 for a short to ground or an open/high resistance. If the circuit tests normal, replace the appropriate window motor.

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

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for DDM or PDM replacement, setup, and programming