Pinpoint Test

CHECK FOR A SHORT TO VOLTAGE IN THE REAR WINDOW DEFROST GRID POWER CIRCUIT
1. Disconnect: Rear Window Defrost Relay.
2. Disconnect: Rear Window Defrost Grid C402A.
3. Ignition ON.
4. Measure:
  
  Fig 1: Checking For Short To Voltage In Rear Window Defrost Grid Power Circuit
  Courtesy of FORD MOTOR CO.
  - Is any voltage present?
  - Yes: REPAIR the circuit.
  - No: GO to step 2 .
CHECK THE REAR WINDOW DEFROST RELAY CONTROL CIRCUIT FOR A SHORT TO GROUND
NOTE: The following step uses a test light to simulate normal circuit loads. Use only the test light recommended in the Special Tool(s) . To avoid connector terminal damage, use the Flex Probe Kit for the test light probe connection to the vehicle. Do not use the test light probe directly on any connector.
1. Start the engine.
2. Measure:
  
  Fig 2: Checking Rear Window Defrost Relay Control Circuit For Short To Ground
  Courtesy of FORD MOTOR CO.
  - Does the test light illuminate?
  - Yes: GO to step 3 .
  - No: INSTALL a new rear window defrost relay.
CHECK THE REAR WINDOW DEFROST RELAY CONTROL CIRCUIT FOR A SHORT TO GROUND WITH THE Heating, Ventilation, and Air Conditioning (HVAC) MODULE DISCONNECTED
NOTE: The following step uses a test light to simulate normal circuit loads. Use only the test light recommended in the Special Tool(s) . To avoid connector terminal damage, use the Flex Probe Kit for the test light probe connection to the vehicle. Do not use the test light probe directly on any connector.
1. Ignition OFF.
2. Disconnect: Heating, Ventilation, and Air Conditioning (HVAC) Module C228A.
3. Ignition ON.
4. Measure:
  
  Fig 3: Checking Rear Window Defrost Relay Control Circuit For Short To Ground
  Courtesy of FORD MOTOR CO.
  - Does the test light illuminate?
  - Yes: REPAIR short to ground in circuit CH122 (WH/OG).
  - No: GO to step 4 .
CHECK FOR CORRECT Heating, Ventilation, and Air Conditioning (HVAC) MODULE OPERATION
1. Inspect the Heating, Ventilation, and Air Conditioning (HVAC) module connectors.
2. Repair:
  - corrosion (install new connector or terminals - clean module pins)
  - damaged or bent pins - install new terminals/pins as necessary
  - pushed-out-pins - install new pins as necessary
3. Reconnect the Heating, Ventilation, and Air Conditioning (HVAC) module connectors. Make sure they seat and latch correctly.
4. Operate the system and determine if the concern is still present.
  - Is the concern still present?
  - Yes: CHECK On-Line Automotive Service Information System (OASIS) for any applicable Technical Service Bulletins (TSBs). If a Technical Service Bulletin (TSB) exists for this concern, DISCONTINUE this test and FOLLOW Technical Service Bulletin (TSB) instructions. If no Technical Service Bulletins (TSBs) address this concern, INSTALL a new Heating, Ventilation, and Air Conditioning (HVAC) module. REFER to HEATING VENTILATION AIR CONDITIONING (HVAC) MODULE (Electronic Manual Temperature Control (EMTC)) or REFER to HEATING VENTILATION AIR CONDITIONING (HVAC) MODULE (Dual Automatic Temperature Control (DATC)).
  - No: The system is operating correctly at this time. The concern may have been caused by module connections. ADDRESS the root cause of any connector or pin issues.