Pinpoint Test N: The Defrost System Will Not Shut Off Automatically - On At All Times

WARNING: This page is about a different car, the 2004 Mercury Mountaineer and 2004 Ford Explorer. However, it is still accessible from the selected car via links, so may be relevant.

N1 CHECK CIRCUIT 186 (BN/LB) FOR A SHORT TO VOLTAGE
- Disconnect: Heated Backlight Relay.
- Key in ON position.
- Is the rear window defrost ON?
Yes

REPAIR the circuit. TEST the system for normal operation.

No

GO to N2.
N2 CHECK THE REAR WINDOW DEFROST RELAY
- Key in OFF position.
- Disconnect: Rear Window Defrost Relay.
- Carry out the rear window defrost relay component test.
  Refer to COMPONENT TESTING for schematic and connector information.
- Is the rear window defrost relay OK?
Yes

GO to N3.

No

INSTALL a new rear window defrost relay. TEST the system for normal operation.
N3 CHECK THE REAR WINDOW DEFROST RELAY
- Key in OFF position.
- Measure the resistance between rear window defrost relay socket pin 86, circuit 1009 (OG/YE) harness side and ground.
  
  Fig 1: Measuring Resistance Between Window Defrost Relay Pin 86 And Ground
  Courtesy of FORD MOTOR CO.
- Is the resistance greater than 10,000 ohms?
Yes

GO to N5.

No

GO to N4.
N4 CHECK CIRCUIT 1009 (OG/YE) FOR A SHORT TO GROUND
- Disconnect: ICM C220a.
- Measure the resistance between rear window defrost relay socket pin 86, circuit 1009 (OG/YE) harness side and ground.
  
  Fig 2: Measuring Resistance Between Window Defrost Relay Pin 86 And Ground
  Courtesy of FORD MOTOR CO.
- Is the resistance greater than 10,000 ohms?
Yes

INSTALL a new ICM. REFER to INFORMATION, GAUGES & WARNING DEVICES . TEST the system for normal operation.

No

REPAIR the circuit. TEST the system for normal operation.
N5 CHECK CIRCUIT 688 (GY/LB) FOR A SHORT TO GROUND
- Disconnect: Function Selector Switch C294b (Manual A/C Only) or DATC Module C228a..
- If equipped with manual A/C, measure the resistance between function selector switch C294b-12, circuit 688 (GY/LB) harness side and ground.
  
  Fig 3: Measuring Resistance Between Function Selector Switch C294B-12 And Ground
  Courtesy of FORD MOTOR CO.
- If equipped with DATC, measure the resistance between DATC module C228a-12, circuit 688 (GY/LB) harness side and ground.
  
  Fig 4: Measuring Resistance Between DATC Module C228A-12 And Ground
  Courtesy of FORD MOTOR CO.
- Is the resistance greater than 10,000 ohms?
Yes

If equipped with manual A/C, INSTALL a new manual climate control assembly.

If equipped with DATC, INSTALL a new DATC climate control assembly. REFER to CLIMATE CONTROL SYSTEM .

No

REPAIR the circuit. TEST the system for normal operation.