2008 F-250 2008 PCED 6.4L Diesel SECTION 5: Pinpoint Tests Report a problem with this article Procedure revision date: 03/09/2010 AF: Glow Plug System AF: Introduction AF1 PRELIMINARY DIAGNOSIS te: If DTCs P0670 and P0684 are present, carry out DTC P0670 diagnosis before diagnosing DTC P0684. Carry out a visual inspection. Record the freeze frame data. Clear the PCM DTCs. GPCM-Black connector disconnected. GPCM-Green connector disconnected. Visually inspect for: pushed out pins corrosion Apply dielectric compound. GPCM-Black connector connected. GPCM-Green connector connected. Verify all glow plug electrical connectors are connected. Carry out the KOER Glow Plug Monitor self-test. Are DTCs P0670, P0671, P0672, P0673, P0674, P0675, P0676, P0677, P0678, or P0684 present? For DTCs P0671, P0672, P0673, P0674, P0675, P0676, P0677 or P0678, GO to AF2. If no symptoms are present, RETURN the vehicle to the customer. For DTC P0670, GO to AF7. For DTC P0684, GO to AF12. The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. If a symptom is present, REFER to Section 3, https://www.motologic.com/car/f18368d0-ca4d-012b-1090-fbb1677812c1/article/7e5ca640-ead5-012d-a214-00259000351c?returnpath=%2fcar%2ff1 1/9
Diagnostic Trouble Codes (DTCs) Present Symptom Chart Index. AF2 DIAGNOSTIC TROUBLE CODES (DTCS) P0671, P0672, P0673, P0674, P0675, P0676, P0677, OR P0678 te: Glow plugs are numbered front to rear with even numbers on the left side of the engine. Glow Plug connector disconnected. Check for loose, damaged, or backed out terminals. ( + ) Glow Plug Connector, Component Side ( - ) Is the resistance between 0.5-2 ohms? GO to AF3. INSTALL a new Glow Plug. REFER to the Workshop Manual Section 303-07, Glow Plug System. Clear the PCM DTCs. AF3 CHECK THE GLOW PLUG VOLTAGE Disconnect the suspect GPCM connector. ( + ) Vehicle Battery ( - ) Vehicle Battery Positive terminal Negative terminal ( + ) Suspect GPCM Connector, Harness Side ( - ) VBAT https://www.motologic.com/car/f18368d0-ca4d-012b-1090-fbb1677812c1/article/7e5ca640-ead5-012d-a214-00259000351c?returnpath=%2fcar%2ff1 2/9
Is the VBAT circuit voltage within plus or minus 0.5 V of the battery voltage? GO to AF4. AF4 CHECK THE GLOW PLUG CIRCUIT FOR AN OPEN ( + ) Suspect GPCM Connector, Harness Side ( - ) Glow Plug Connector, Harness Side Is the resistance less than 5 ohms? GO to AF5. AF5 CHECK THE GLOW PLUG CIRCUIT FOR A SHORT TO GROUND ( + ) Suspect GPCM Connector, Harness Side ( - ) Is the resistance greater than 10K ohms? GO to AF6. AF6 CHECK THE GLOW PLUG CIRCUIT FOR A SHORT TO VOLTAGE https://www.motologic.com/car/f18368d0-ca4d-012b-1090-fbb1677812c1/article/7e5ca640-ead5-012d-a214-00259000351c?returnpath=%2fcar%2ff1 3/9
( + ) Suspect GPCM Connector, Harness Side ( - ) Is any voltage indicated? INSTALL a new GPCM. REFER to the Workshop Manual Section 303-07, Glow Plug System. Clear the PCM DTCs. AF7 DTC P0670: CHECK THE GPE CIRCUIT FOR AN OPEN IN THE HARNESS PCM-E connector disconnected. GPCM-Green connector disconnected. ( + ) GPCM-Green Connector, Harness Side ( - ) PCM-E Connector, Harness Side GPE - Pin 8 GPE - Pin 45 Is the resistance less than 5 ohms? GO to AF8. AF8 CHECK THE GPE CIRCUIT FOR A SHORT TO GROUND IN THE HARNESS ( + ) GPCM-Green Connector, Harness Side ( - ) GPE - Pin 8 Is the resistance greater than 10K ohms? https://www.motologic.com/car/f18368d0-ca4d-012b-1090-fbb1677812c1/article/7e5ca640-ead5-012d-a214-00259000351c?returnpath=%2fcar%2ff1 4/9
GO to AF9. AF9 CHECK THE GPE CIRCUIT FOR A SHORT TO POWER IN THE HARNESS ( + ) GPCM-Green Connector, Harness Side ( - ) GPE - Pin 8 Is any voltage indicated? GO to AF10. AF10 CHECK THE GPCM FOR VOLTAGE GPCM-Black connector disconnected. ( + ) GPCM-Black Connector, Harness Side ( - ) VPWR - Pin 9 Is the voltage greater than 10 V? GO to AF11. AF11 CHECK THE GPE CONTROL CIRCUIT te: With the key ON, engine OFF the PCM provides a path to ground for the GPE circuit. GPCM-Black connector connected. https://www.motologic.com/car/f18368d0-ca4d-012b-1090-fbb1677812c1/article/7e5ca640-ead5-012d-a214-00259000351c?returnpath=%2fcar%2ff1 5/9
PCM-E connector connected. ( + ) Vehicle Battery ( - ) GPCM-Green Connector, Harness Side Positive terminal GPE - Pin 8 Is the voltage greater than 10 V? INSTALL a new GPCM. REFER to the Workshop Manual Section 303-07, Glow Plug System. GO to AF17. Clear the PCM DTCs. AF12 DTC P0684: CHECK THE GPD CIRCUIT FOR AN OPEN IN THE HARNESS PCM-E connector disconnected. GPCM-Green connector disconnected. ( + ) GPCM-Green Connector, Harness Side ( - ) PCM-E Connector, Harness Side GPD - Pin 9 GPD - Pin 83 Is the resistance less than 5 ohms? GO to AF13. AF13 CHECK THE GPD CIRCUIT FOR A SHORT TO GROUND IN THE HARNESS ( + ) GPCM-Green Connector, Harness Side ( - ) GPD - Pin 9 https://www.motologic.com/car/f18368d0-ca4d-012b-1090-fbb1677812c1/article/7e5ca640-ead5-012d-a214-00259000351c?returnpath=%2fcar%2ff1 6/9
Is the resistance greater than 10K ohms? GO to AF14. AF14 CHECK THE GPD CIRCUIT FOR A SHORT TO POWER IN THE HARNESS ( + ) GPCM-Green Connector, Harness Side ( - ) GPD - Pin 9 Is any voltage indicated? GO to AF15. AF15 CHECK THE GPCM FOR VOLTAGE GPCM-Black connector disconnected. ( + ) GPCM-Black Connector, Harness Side ( - ) VPWR - Pin 9 Is the voltage greater than 10 V? GO to AF16. AF16 CHECK THE GPCM OPERATION https://www.motologic.com/car/f18368d0-ca4d-012b-1090-fbb1677812c1/article/7e5ca640-ead5-012d-a214-00259000351c?returnpath=%2fcar%2ff1 7/9
GPCM-Black connector connected. GPCM-Green connector connected. Connect a 5 amp fused jumper wire between the following: Point A PCM-E Connector, Harness Side GPE - Pin 45 Point B ( + ) PCM-E Connector, Harness Side ( - ) GPD - Pin 83 Is the voltage between 5-12 V? GO to AF17. INSTALL a new GPCM. REFER to the Workshop Manual Section 303-07, Glow Plug System. Clear the PCM DTCs. AF17 CHECK FOR CORRECT PCM OPERATION Disconnect all the PCM connectors. Visually inspect for: pushed out pins corrosion Connect all the PCM connectors and make sure they seat correctly. Carry out the PCM self-test. Verify the concern is still present. Is the concern still present? INSTALL a new PCM. REFER to Section 2, Flash Electrically Erasable Programmable Read Only Memory (EEPROM). The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. https://www.motologic.com/car/f18368d0-ca4d-012b-1090-fbb1677812c1/article/7e5ca640-ead5-012d-a214-00259000351c?returnpath=%2fcar%2ff1 8/9
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