Pinpoint Test A: A Single Power Window Is Inoperative - LF

Glass, Frames and Mechanisms

Pinpoint Tests

Pinpoint Test A: A Single Power Window is Inoperative - LF

Refer to Wiring Diagram Set 100, Power Windows for schematic and connector information. Diagrams By Number

Normal Operation

Under normal operation, the LF power window motor microprocessor receives power at all times through circuit SBP01 (RD) and from the accessory delay relay through circuit CBP41 (BU). Ground is provided at all times through circuit GD143 (BK/VT). The master window control switch provides voltage input to the power window motor microprocessor through circuit CPW10 (YE/VT) to operate the driver window down, and voltage input through circuit CPW11 (BU/GY) to operate the driver window up.

This pinpoint test is intended to diagnose the following:
- Fuse(s)
- Wiring, terminals or connectors
- Window control switch
- Front door window regulator motor

PINPOINT TEST A: A SINGLE POWER WINDOW IS INOPERATIVE - LF

NOTICE: Use the correct probe adapter(s) from the Flex Probe Kit when making measurements. Failure to use the correct probe adapter(s) may damage the connector.

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A1 CHECK THE POWER TO THE WINDOW MOTOR

- Ignition OFF.
- Disconnect: LF Window Power Window Motor C540.
- Measure the voltage between LF power window motor C540-3, circuit SBP01 (RD), harness side and ground.

- Is the voltage greater than 10 volts?

Yes
GO to A2.

No
VERIFY the Smart Junction Box (SJB) fuse 1 (30A) is OK. If OK, REPAIR circuit SBP01 (RD) for an open. DE-INITIALIZE, then INITIALIZE the LF power window motor. REFER to Window Motor Initialization Service and Repair. TEST the system for normal operation.

If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short. REPAIR the circuit. DE-INITIALIZE, then INITIALIZE the LF power window motor. REFER to Window Motor Initialization Service and Repair. TEST the system for normal operation. Diagrams By Number

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A2 CHECK THE LF WINDOW MOTOR DELAYED ACCESSORY FEED

- Ignition ON.
- Measure the voltage between LF power window motor C540-2, circuit CBP41 (BU), harness side and ground.

- Is the voltage greater than 10 volts?

Yes
GO to A3.

No
VERIFY SJB fuse 41 (15A) is OK. If OK, REPAIR circuit CPB41 (BU) for an open. DE-INITIALIZE, then INITIALIZE the LF power window motor. REFER to Window Motor Initialization Service and Repair. TEST the system for normal operation.

If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short. REPAIR the circuit. DE-INITIALIZE, then INITIALIZE the LF power window motor. REFER to Window Motor Initialization Service and Repair. TEST the system for normal operation. Diagrams By Number

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A3 CHECK THE LF MOTOR GROUND

- Ignition OFF.
- Open the front door to disable delayed accessory power.
- Measure the resistance between LF power window motor C540-8, circuit GD143 (BK/VT), harness side and ground.

- Is the resistance less than 5 ohms?

Yes
For Expedition, GO to A4. For Navigator, GO to A5.

No
REPAIR circuit GD143 (BK/VT) for an open. DE-INITIALIZE, then INITIALIZE the LF power window motor. REFER to Window Motor Initialization Service and Repair. TEST the system for normal operation.

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A4 CHECK THE FRONT WINDOW SWITCH TO LF MOTOR FEEDS

- Disconnect: Master Window Control Switch C504A.
- Measure the resistance between LF power window motor C540, harness side and master window control switch C504A, harness side using the following chart:

- Is the resistance less than 5 ohms?

Yes
GO to A6.

No
REPAIR circuit CPW11 (BU/GY), CPW10 (YE/VT) or CPW29 (VT/GY) for an open. DE-INITIALIZE, then INITIALIZE the LF power window motor. REFER to Window Motor Initialization Service and Repair. TEST the system for normal operation.

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A6 CHECK THE MASTER WINDOW CONTROL SWITCH

- Carry out the window control switch component test.
Refer to Wiring Diagrams for component testing. Diagrams By Number

- Did the window control switch pass the component test?

Yes
INSTALL a new LF power window motor. REFER to Window Regulator Motor - Front Door Window Regulator Motor - Front Door. INITIALIZE the LF door window motor. REFER to Window Motor Initialization Service and Repair. TEST the system for normal operation.

No
INSTALL a new master window control switch. REFER to Window Control Switch Service and Repair. TEST the system for normal operation.

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