For 1990-2009 cars

### Circuit Description

The driver window switch signal circuits provide inputs to the intelligent switching unit (ISU) when the driver window switch is activated to the UP or DOWN position. These inputs allow the ISU to detect a window UP or DOWN request. The ISU provides power and ground to the driver window switch. When the driver window switch is activated to the express DOWN position, power is supplied through the window switch to the signal circuit, which is pulled high. When the ISU detects high voltage on the signal circuit, it will command the window in the DOWN direction. When the switch is pressed again, the command ceases.

### Conditions for Setting the DTC

• | The ISU detects an open or short to voltage on a driver window motor feed circuit.

• | Condition must be present for greater than 20 seconds.

### Action Taken When the DTC Sets

Stores a current and history DTC 029 in ISU memory.

### Conditions for Clearing the DTC

• | The ISU no longer detects an open or short to voltage on a driver window motor circuit.

• | A history DTC will clear after 40 consecutive ignition cycles if the condition for the malfunction is no longer present.

### Diagnostic Aids

• | A short to ground condition will cause the ISU Power Window Fuse to blow, causing an open condition to the driver window circuits.

• | If the DTC does not reset after the code is cleared, then the problem may be intermittent. Refer to Testing for Intermittent Conditions and Poor Connections .

### Test Description

The numbers below refer to the step numbers on the diagnostic table.

1. This step tests for normal operation of the window switch.

2. This step tests for an open in the window circuit.

Step | Action | Values | Yes | No
--- | --- | --- | --- | ---
Schematic Reference: Moveable Window Schematics Connector End View Reference: Window Systems Connector End Views
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle
2 | Inspect the 20A ISU Power Window Fuse E. Is the fuse open? | -- | Go to Step 4 | Go to Step 3
3 |

1. Turn OFF the ignition.
2. Disconnect the intelligent switching unit (ISU).
3. Connect a DVM between the window motor circuits at the ISU connector.

Does the resistance measure within the specified value?

0.8-1.2 ohms

Go to Step 6

Go to Step 5

4 | Test the motor feed circuits of the driver window motor for a short to ground. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 10 | Go to Step 9
5 | Test the motor feed circuits of the driver window motor for an open. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 7
6 | Inspect for poor connections at the harness connector of the ISU. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 8
7 | Inspect for poor connections at the harness connector of the window motor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 9
8 | Important: Perform the program procedure for the ISU. Replace the ISU. Did you complete the replacement? | -- | Go to Step 11 | --
9 | Replace the driver window motor. Did you complete the replacement? | -- | Go to Step 11 | --
10 | Replace the 20A ISU Power Window Fuse E. Did you complete the replacement? | -- | Go to Step 11 | --
11 |

1. Use the scan tool in order to clear the DTCs.
2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

--

Go to Step 2

System OK