Left Front Door Module

U0037 - Lin Bus Circuit Low






For a complete wiring diagram, refer to.

• When Monitored: Continuously when the ignition is on.

• Set Condition: The module detects a short to ground on the LIN Bus circuit.






Test Step 1 - VERIFY DTC IS ACTIVE

• Turn the ignition on.

• With the scan tool, read active Door Module DTCs.

Is this DTC active?

Yes

• Go to Test Step 2

No

• Refer to => Non-DTC Based Diagnostics and perform the Stored Lost Communication DTCs diagnostic procedure. Stored Lost Communication DTCs

Test Step 2 - CHECK THE LIN BUS CIRCUIT







• Turn the ignition off.

• Disconnect the Driver Window/Door Lock Switch C1 connector.

• Turn the ignition on.

• Measure the voltage between the (D903) LIN Bus circuit (Cavity 3 or Cavity 6) and the (Q911) Driver Window Switch Sense Return circuit.

Is the voltage above 7.0 volts?

No

• Go to Test Step 3

Yes

• Replace the Driver Window/Door Lock Switch.

• Perform the Body Verification Test. Refer to => Non-DTC Based Diagnostics. Body Interior

Test Step 3 - (D903) LIN BUS CIRCUIT SHORTED TO GROUND







• Turn the ignition off.

• Disconnect the Driver Door Module C5 connector.

• Measure the resistance between Ground and the (D903) LIN Bus circuit in the Door Module C5 connector.

Is the resistance below 10,000 Ohms?

Yes

• Repair the (D903) LIN Bus circuit for a short to the ground.

• Perform the Body Verification Test. Refer to => Non-DTC Based Diagnostics. Body Interior

No

• Go to Test Step 4

Test Step 4 - (D903) LIN BUS CIRCUIT SHORTED TO THE (Q911) DRIVER WINDOW SWITCH SENSE RETURN CIRCUIT

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• Measure the resistance between the (D903) LIN Bus circuit and the (Q911) Driver Window Switch Sense Return circuit in the Door Module C5 connector.

Is the resistance below 10,000 Ohms?

Yes

• Repair the (D903) LIN Bus circuit for a short to the (Q911) Driver Window Switch Sense Return circuit.

• Perform the Body Verification Test. Refer to => Non-DTC Based Diagnostics. Body Interior

No

• Replace the Driver Door Module.

• Perform the Body Verification Test. Refer to => Non-DTC Based Diagnostics. Body Interior