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Pinpoint Test H: DTC B1676

WARNING: This page is about a different car, the 2010 Lincoln Town Car. However, it is still accessible from the selected car via links, so may be relevant.
  1. H1 RETRIEVE ALL Continuous Memory Diagnostic Trouble Codes (CMDTCs) IN ALL MODULES 
    • Enter the following diagnostic mode on the diagnostic tool: Self Test - All CMDTCs
    • Is B1317, B1318 or B1676 present in more than one module AND P0563, P0620, P0625, P0626 or P065B present in the PCM? 
    1. YES  : REFER to CHARGING SYSTEM - GENERAL INFORMATION article for diagnosis of the battery and charging system. CLEAR all CMDTCs. TEST the system for normal operation.
    2. NO  : Go to  H2.
  2. H2 CHECK BATTERY CONDITION 
    • Refer to BATTERY, MOUNTING & CABLES article and carry out the Battery - Condition Test
    • Does the battery pass the condition test? 
    1. YES  : If the battery passed the condition test but required a recharge, REFER to CHARGING SYSTEM - GENERAL INFORMATION article to diagnose the charging system. CLEAR all CMDTCs. TEST the system for normal operation.
    2. If the battery passed the condition test and did not require a recharge, go to  H3.
    3. NO  : INSTALL a new battery. CLEAR all CMDTCs. TEST the system for normal operation.
  3. H3 CHECK CHARGING SYSTEM VOLTAGE 
    NOTE: Do not allow the engine speed to increase above 2,000 RPM while performing this step or the generator may self excite and result in default charging system output voltage. If engine speed goes above 2,000 RPM, shut the vehicle OFF and restart the engine before performing this step.
      Fig 1: Checking Charging System Voltage
      GF0001354Courtesy of FORD MOTOR CO.
    • Measure the voltage of the battery with and without a load on the charging system as follows:
      • Turn off all accessories and run the engine at 1,500 RPM for a minimum of 2 minutes while measuring battery voltage.
      • Turn on headlights and HVAC fan on high and run engine at 1,500 RPM for a minimum of 2 minutes while measuring battery voltage.
    • Are the voltages between 13 and 15.2 volts? 
    1. YES  : Go to  H4.
    2. NO  : REFER to CHARGING SYSTEM - GENERAL INFORMATION article to diagnose the charging system. CLEAR all CMDTCs. TEST the system for normal operation.
  4. H4 CHECK FOR VOLTAGE MONITORING THE MODULE SUPPLY VOLTAGE (VBAT_CC) HVAC PID 
    • Key in ON position.
    • Enter the following diagnostic mode on the diagnostic tool: VBAT_CC HVAC PID
    • Monitor the battery voltage VBAT_CC HVAC PID.
    • Is the battery voltage less than 9 or greater than 15.5 volts? 
    1. YES  : If voltage is less than 9 volts, go to  H5.

      If voltage is greater than 15.5 volts, INSTALL a new HVAC module. REFER to CLIMATE CONTROL article. CLEAR all CMDTCs. REPEAT the self-test.

    2. NO  : Go to  H8.
  5. H5 CHECK CIRCUIT 57 (BK) FOR AN OPEN 
    • Key in OFF position.
    • Disconnect: HVAC Module C228a
      • Fig 2: Measuring Resistance
      GF0047635Courtesy of FORD MOTOR CO.
    • Measure the resistance between HVAC module C228a-2, circuit 57 (BK), harness side and ground.
    • Is the resistance less than 5 ohms? 
    1. YES  : Go to  H6.
    2. NO  : REPAIR circuit 57 (BK) for an open. TEST the system for normal operation.
  6. H6 CHECK CIRCUIT 1566 (RD/YE) FOR B+ 
    • Disconnect: HVAC Module C228b
      • Fig 3: Measuring Voltage
      GF0047636Courtesy of FORD MOTOR CO.
    • Measure the voltage between HVAC module C228b-11, circuit 1566 (RD/YE), harness side and ground.
    • Is the voltage B+? 
    1. YES  : Go to  H7.
    2. NO  : VERIFY Central Junction Box (CJB) fuse 27 (10A) is OK. If OK, REPAIR circuit 1566 (RD/YE) for an open. TEST the system for normal operation. If not OK, REFER to SYSTEM WIRING DIAGRAMS article to identify the possible causes of the circuit short.
  7. H7 CHECK CIRCUIT 1812 (BN/WH) FOR B+ 
    • Key in ON position.
      • Fig 4: Measuring Voltage
      GF0047637Courtesy of FORD MOTOR CO.
    • Measure the voltage between HVAC module C228b-22, circuit 1812 (BN/WH), harness side and ground.
    • Is the voltage B+? 
    1. YES  : REFER to MODULE COMMUNICATIONS NETWORK article to diagnose a network concern.
    2. NO  : VERIFY CJB fuse 15 (10A) is OK. If OK, REPAIR circuit 1812 (BN/WH) for an open. TEST the system for normal operation. If not OK, REFER to the SYSTEM WIRING DIAGRAMS article to identify the possible causes of the circuit short.
  8. H8 CHECK THE MODULE CONNECTION 
    • Carry out the HVAC Module Cold Boot Process .
    • Carry out the HVAC Module - Electronic Automatic Temperature Control (EATC) and HVAC Module - Dual Automatic Temperature Control (DATC) On-Demand Self Test. Refer to HVAC Module Self-Test .
    • Operate the system.
    • Does the concern return? 
    1. YES  : INSTALL a new HVAC module. REFER to CLIMATE CONTROL article. TEST the system for normal operation.
    2. NO  : The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
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