Pinpoint Test E: The Defrost System Will Not Shut Off Automatically

Glass, Frames and Mechanisms

Pinpoint Tests

Pinpoint Test E: The Defrost System Will Not Shut Off Automatically

Refer to Wiring Diagram Set 56, Heated Window for schematic and connector information. Diagrams By Number

Normal Operation

When the rear window defrost switch on the HVAC module is pressed, a ground signal is sent to the Smart Junction Box (SJB) on circuit 1426 (PK). The SJB then grounds circuit 1389 (WH) which energizes the rear window defrost relay. When the rear window defrost relay is active, voltage is supplied to the rear window defrost grid through circuit 186 (BN/LB). The rear window defrost grid is grounded by circuit 1205 (BK). The SJB provides rear window defrost status to the HVAC module through circuit 1427 (TN/LB).

This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Rear window defrost switch
- Rear window defrost relay
- SJB



PINPOINT TEST E: THE DEFROST SYSTEM WILL NOT SHUT OFF AUTOMATICALLY

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E1 CHECK THE REAR WINDOW DEFROST RELAY FOR AN OPEN OR INTERNAL SHORT


- Ignition ON.
- Disconnect: Rear Window Defrost Relay.
- Carry out the Rear Window Defrost Relay Component Test.
- Does the rear window defrost relay pass the component test?

Yes
GO to E2.

No
INSTALL a new rear window defrost relay. CLEAR the DTCs. REPEAT the self-test.

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E2 CHECK CIRCUIT 186 (BN/LB) FOR A SHORT TO VOLTAGE


- Disconnect: Rear Window Defrost C402A (coupe), C402 (convertible).
- Measure the voltage between heated rear window C402A-1 (coupe), C402-1 (convertible), circuit 186 (BN/LB), harness side and ground.




- Is the voltage greater than 10 volts?

Yes
REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.

No
GO to E3.

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E3 CHECK CIRCUIT 1389 (WH) FOR A SHORT TO GROUND


- Ignition OFF.
- Disconnect: SJB C2280C.
- Measure the resistance between the rear window defrost relay pin 86, circuit 1389 (WH), harness side and ground.




- Is the resistance greater than 10,000 ohms?

Yes
GO to E4.

No
REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.

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E4 CHECK THE SJB FOR CORRECT OPERATION


- Disconnect all of the SJB connectors.
- Check for:
- corrosion.
- pushed-out pins.
- Connect all of the SJB connectors and make sure they seat correctly.
- Operate the system and verify the concern is still present.
- Is the concern still present?

Yes
INSTALL a new SJB. REPEAT the self-test. TEST the system for normal operation.

No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.

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