Pinpoint Test J: The Defrost System Is Inoperative

WARNING: This page is about a different car, the 2006 Mercury Milan, 2006 Lincoln Zephyr, and 2006 Ford Fusion. However, it is still accessible from the selected car via links, so may be relevant.

J1 CHECK THE DIAGNOSTIC TROUBLE CODES (DTCS)
- Refer to the results from the previous smart junction box (SJB) self-test
- Was DTC B1345 retrieved?
Yes : GO to J2.

No : GO to J3.
J2 CHECK CIRCUIT CH122 (WH/OG) FOR A SHORT TO GROUND
- Key in OFF position.
- Disconnect: SJB C2280D.
- Disconnect: EATC C228A or EMTC C2357A.
- Measure the resistance between SJB C2280D-16, circuit CH122 (WH/OG), harness side and ground.
  
  Fig 1: Checking Circuit CH122 (WH/OG) For Short To Ground
  Courtesy of FORD MOTOR CO.
- Is the resistance greater than 10,000 ohms?
Yes : INSTALL a new EATC or EMTC module. REFER to CLIMATE CONTROL . TEST the system for normal operation.

No : REPAIR the circuit. TEST the system for normal operation.
J3 CHECK THE SJB HEATED BACKLIGHT REQUEST PID
- Key in ON position.
- Monitor the SJB heated backlight request PID while pressing the rear defrost switch.
- Does the SJB heated backlight request PID value agree with the rear defrost switch when pressed?
Yes : GO to J5.

No : GO to J4.
J4 CHECK CIRCUIT CH122 (WH/OG) FOR AN OPEN CIRCUIT
- Key in OFF position.
- Disconnect: SJB C2280D.
- Disconnect: EATC C228A or EMTC C2357A.
- Measure the resistance between SJB C2280D-16, circuit CH122 (WH/OG), harness side and EATC C228A-10 or EMTC C2357A-10, circuit CH122 (WH/OG), harness side.
  
  Fig 2: Checking Circuit CH122 (WH/OG) For Open Circuit
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
Yes : INSTALL a new EATC or EMTC module. REFER to CLIMATE CONTROL . TEST the system for normal operation.

No : REPAIR the circuit. TEST the system for normal operation.
J5 CHECK THE SJB OUTPUT
- Turn the rear defroster ON. Measure the voltage across the rear window defrost grid as shown.
  
  Fig 3: Checking SJB Output
  Courtesy of FORD MOTOR CO.
- Is the voltage greater than 10 volts?
Yes : REPAIR the rear window defrost grid or INSTALL a new rear window glass. REFER to WINDOW GRID WIRE REPAIR , WINDOW GLASS - REAR . TEST the system for normal operation.

No : GO to J6.
J6 CHECK FOR POWER TO THE SJB HEATED BACKLIGHT CIRCUIT
- Key in OFF position.
- Disconnect: SJB C2280A.
- Measure the voltage between SJB C2280A-29, circuit SBB06 (BN/RD), harness side and ground.
  
  Fig 4: Checking For Power To SJB Heated Backlight Circuit
  Courtesy of FORD MOTOR CO.
- Is the voltage greater than 10 volts?
Yes : GO to J7.

No : VERIFY battery junction box (BJB) fuse 6 (40A) is OK. If OK, REPAIR the circuit. TEST the system for normal operation.
J7 CHECK CIRCUIT A_CLS38 (VT/WH) VOLTAGE
- Key in OFF position.
- Connect: SJB C2280A.
- Disconnect: Antenna module C402B.
- Key in ON position.
- Turn the rear defroster ON.
- Measure the voltage between antenna module C402B, circuit CLS38 (VT/WH), harness side and ground.
  
  Fig 5: Checking Circuit A_CLS38 (VT/WH) Voltage
  Courtesy of FORD MOTOR CO.
- Is the voltage greater than 10 volts?
Yes : INSPECT antenna module jumper harness for damage and repair as necessary. If jumper harness is OK, INSTALL a new antenna module.

No : VERIFY SJB fuse 8 (30A) is OK. If OK, GO to J8.
J8 CHECK CIRCUIT A_CLS38 (VT/WH) FOR AN OPEN
- Disconnect: SJB C2280E.
- Key in OFF position.
- Measure the resistance between SJB C2280E-1, circuit CLS38 (VT/WH), harness side and antenna module C402B, circuit CLS38 (VT/WH), harness side.
  
  Fig 6: Checking Circuit A_CLS38 (VT/WH) For Open
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
Yes : GO to J9.

No : REPAIR the circuit(s). TEST the system for normal operation.
J9 CHECK FOR CORRECT SJB OPERATION
- Disconnect all SJB connectors.
- Check for:
  - Corrosion.
  - Pushed-out pins.
- Connect all 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. REFER to MULTIFUNCTION ELECTRONIC CONTROL MODULES for the removal and installation procedure. TEST the system for normal operation.

No : The system is operating correctly at this time. Concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.