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Pinpoint Test C: The Charging System Warning Indicator is On With the Engine Running and No Charging System DTCs Present

WARNING: This page is about a different car, the 2009 Mercury Grand Marquis and 2009 Ford Crown Victoria. However, it is still accessible from the selected car via links, so may be relevant.

Refer to appropriate SYSTEM WIRING DIAGRAMS article, Charging System for schematic and connector information.

Normal Operation 

With the engine running, the charging system warning indicator is off. The A circuit 35 (OG/LB) from the battery B+ to the generator regulator is 13-15 volts. This voltage feedback is used by the regulator to maintain the battery voltage at the desired setpoint. The S (stator) circuit (internal to the generator) is used to monitor generator operation. This circuit and other regulator internal conditions are checked by the regulator to allow the PCM to turn off the charging system warning indicator by sending a message over the controller area network (CAN) bus to the instrument cluster (IC). The positive battery output (B+) circuit 38 (RD) is the generator output supplied to the battery and electrical system.

This pinpoint test is intended to diagnose the following:

PINPOINT TEST C: THE CHARGING SYSTEM WARNING INDICATOR IS ON WITH THE ENGINE RUNNING AND NO CHARGING SYSTEM DTCs PRESENT 

NOTE: Make sure battery voltage is greater than 12.2 volts prior to carrying out this pinpoint test.
NOTE: Do not have a battery charger attached during vehicle testing.
  1. C1 CHECK THE BATTERY CONDITION 
    • Carry out the Battery - Condition Test to determine if the battery can hold a charge and is OK for use. Refer to BATTERY, MOUNTING & CABLES article.
    • Does the battery pass the condition test? 
    1. YES  : Go to  C2.
    2. NO  : INSTALL a new battery. REFER to BATTERY, MOUNTING & CABLES article. TEST the system for normal operation.
  2. C2 CHECK THE GENERATOR B+ CONNECTION 
    • Key in OFF position.
    • Inspect generator C102b connection. Connection should be tight.
      • Fig 1: Checking Generator B+ Circuit For Voltage
      GF0004524Courtesy of FORD MOTOR CO.
    • Measure the voltage between generator C102b, circuit 38 (RD) and ground.
    • Is generator C102b connection tight and does the generator B+ measure battery voltage? 
    1. YES  : Go to  C3.
    2. NO  : TIGHTEN the generator B+ connection or REPAIR the circuit. CLEAR the any DTCs. REPEAT the self-test. TEST the system for normal operation.
  3. C3 CHECK THE VOLTAGE DROP IN THE B+ circuit 38 (RD)  
      Fig 2: Checking B+ Circuit
      GF0014500Courtesy of FORD MOTOR CO.
    • With the engine running, measure the voltage drop between generator B+ C102b, circuit 38 (RD) and the positive battery terminal.
    • Is the voltage drop less than 0.5 volt? 
    1. YES  : Go to  C4.
    2. NO  : CHECK for any corrosion in the B+ C102b, circuit 38 (RD), positive battery cable and/or connections. REPAIR as necessary. TEST the system for normal operation.
  4. C4 CHECK THE DTCs IN THE PCM 
    • Key in OFF position.
    • Connect the diagnostic tool.
    • Key in START position.
    • Enter the following diagnostic mode on the diagnostic tool: Retrieve PCM DTCs
    • Use the recorded PCM DTCs from the continuous and on-demand self tests.
    • Are any PCM DTCs recorded? 
    1. YES  : For all DTCs EXCEPT charging system DTCs, REFER to the Introduction - Gasoline Engines article. If any charging system DTCs are present, go to Pinpoint Test B . If referred here by the Introduction - Gasoline Engines , go to  C5.
    2. NO  : Go to  C5.
  5. C5 MONITOR PID GENFIL 
    • With the engine running, monitor PID GENFIL.
    • Does PID GENFIL show fault? 
    1. YES  : Go to  C6.
    2. NO  : REPAIR/INSTALL a new instrument cluster (IC), IC-to-PCM connection or the PCM. TEST the system for normal operation.
  6. C6 MONITOR PID VPWR 
    • With the engine running, monitor PIDS VPWR, GENFIL, GENVDSD.
    • Is PID VPWR greater than 15.6 volts? 
    1. YES  : Go to  C7.
    2. NO  : Go to  C8.
  7. C7 CHECK PCM VPWR PID 
      Fig 3: Checking Charging System Voltage
      GF0001354Courtesy of FORD MOTOR CO.
    • With the engine running, measure the battery voltage.
    • Monitor the VPWR PID.
    • Are the battery voltage and VPWR PID within 0.6 volt of each other? 
    1. YES  : Go to  C8.
    2. NO  : Go to  C9.
  8. C8 MEASURE PCM INPUT VOLTAGE 
    • Key in OFF position.
    • Disconnect: PCM C175b
    • Key in ON position.
      • Fig 4: Checking Circuit For Voltage
      GF0016081Courtesy of FORD MOTOR CO.
    • Measure the voltage between PCM input voltage pins 35, 36 and 45 to PCM ground pin 10.
    • Are voltages within 0.5 volt of PID VPWR? 
    1. YES  : INSTALL a new PCM.
    2. NO  : REPAIR high resistance or loose connections between C175b-35 circuit 361 (RD), C175b-36 circuit 361 (RD), C175b-45 circuit 729 (RD/WH) PCM power circuits or C175b-10, circuit 57 (BK), PCM ground circuit.
  9. C9 MONITOR THE PCM PID GENERATOR MONITOR WITH KEY ON/ENGINE RUNNING 
    • Key in START position.
    • With the engine at idle, wait 15 seconds for the GENVDSD PID to increase to greater than 13 volts.
    • Monitor PID GENMON at idle and 3,000 RPM.
    • Does the GENMON PID read between 3% and 98% at engine idle speed and at 3,000 RPM? 
    1. YES  : Go to  C10.
    2. NO  : Go to  C11.
  10. C10 MONITOR PID GENVDSD 
    • With the engine running, monitor PID GENVDSD.
    • Is PID GENVDSD greater than 15.2 volts? 
    1. YES  : REPAIR connection on circuit 35 (OG/LB). INSPECT generator C102a-3 for damage. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation. If no problems are found, INSTALL a new generator. REFER to GENERATOR & REGULATOR article. TEST the system for normal operation.
    2. NO  : REFLASH or INSTALL a new PCM.
  11. C11 CHECK FOR SHORTED CIRCUITS 
    • Key in OFF position.
    • Disconnect: Generator C102a
    • Verify that PID GENMON reads 100%.
    • Carry out the Wiggle Test of wiring to determine if PID GENMON changes from 100%.
    • Does PID GENMON change from 100%? 
    1. YES  : REPAIR short circuit on C102a-1 1817 (YE).
    2. NO  : Go to  C12.
  12. C12 CHECK THE PCM PID GENERATOR MONITOR INPUT TO THE PCM 
      Fig 5: Connecting Fused Jumper Wire
      GF0016079Courtesy of FORD MOTOR CO.
    • Connect a fused (10A) jumper wire between generator C102a-1, circuit 1817 (YE), harness side and ground.
    • Key in ON position.
    • Monitor the GENMON PID while carrying out a Wiggle Test on the wire harness.
    • Does the GENMON PID read 0%? 
    1. YES  : REPAIR open connection on circuit 1817 (YE) C102a-1, and PCM C175e-26. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
    2. NO  : INSTALL a new generator. REFER to GENERATOR & REGULATOR article. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
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