2000 PCED OBD II Diesel
SECTION 5: Pinpoint Tests

QB: Glow Plug System (California)
  QB: Introduction  

 

QB1 CHECK FOR DTC P0671 DTC P0678

Is one or more of the following codes present: DTC P0671, DTC P0672, DTC P0673, DTC P0674, DTC P0675, DTC P0676, DTC P0677, DTC P0678?
YesNo
GO to QB2.GO to QB6.
 

QB2 CHECK FOR OPEN/SHORTED GLOW PLUG CIRCUIT

Is the resistance greater than 5 ohms? (Typical resistance value of a good glow plug and wiring is 1 ohm.)
YesNo
GO to QB3.INSTALL a new glow plug indicated by DTC. REFER to Glow Plug System in the workshop manual. RESTORE system. CLEAR DTC's and RETEST.
 

QB3 CHECK FOR OPEN GLOW PLUG CIRCUIT GPCM TO VALVE COVER CONNECTOR

Is the resistance greater than 5 ohms? (Typical resistance value is less than 1 ohm.)
YesNo
REPAIR open circuit between GPCM connector and valve cover connector. RESTORE system. CLEAR DTCs and RETEST.GO to QB4.
 

QB4 CHECK FOR OPEN GLOW PLUG CIRCUIT UNDER VALVE COVER (UVC) HARNESS

Is the resistance greater than 5 ohms? (Typical resistance value is less than 1 ohm.)
YesNo
Open is in valve cover gasket or under valve cover (UVC) harness. INSTALL new as necessary. RESTORE system. CLEAR DTCs and RETEST.GO to QB5.
 

QB5 CHECK FOR OPEN GLOW PLUG

Is the resistance greater than 5 ohms? (Typical cold resistance is less than 1ohm.)
YesNo
INSTALL a new failed glow plug. RESTORE system. CLEAR DTCs and RETEST.INSTALL a new GPCM. RESTORE system. CLEAR DTCs and RETEST.
 

QB6 CHECK FOR DTC P0670

Is DTC P0670 present?
YesNo
GO to QB7.GO to QB11.
 

QB7 CHECK FOR OPEN IN CONTROL LINE

Is the resistance greater than 5 ohms? (Typical resistance value is less than 1 ohm.)
YesNo
REPAIR open in circuit 1086 (PK/OG). RESTORE system. CLEAR DTCs and RETEST.GO to QB8.
 

QB8 CHECK FOR SHORT TO POWER IN CONTROL CIRCUIT

Is the voltage greater than 5 volts? (Typical voltage should be 0 volts.)
YesNo
REPAIR short to power in circuit 1086 (PK/OG). RESTORE system. CLEAR DTCs and RETEST.GO to QB9.
 

QB9 CHECK FOR SHORT TO GROUND IN CONTROL CIRCUIT

Is the resistance less than 1 ohm? (Typical voltage should be 12 volts.)
YesNo
REPAIR short to ground in circuit 1086 (PK/OG). RESTORE system. CLEAR DTCs and RETEST.GO to QB10.
 

QB10 CHECK MODULE FUNCTION

Is the voltage low (less than 1 V) when glow plugs are on and high (greater than 10 V) when glow plugs are off?
YesNo
INSTALL a new GPCM. RESTORE system. CLEAR DTCs and RETEST.INSTALL a new PCM. RESTORE system. CLEAR DTCs and RETEST.
 

QB11 CHECK FOR DTC P0683

Is DTC P0683 present? Clear DTCs and retest, make sure there is no DTC P0670 present. If DTC P0670 is present, perform DTC P0670 pinpoint test sequence and fix problem before performing DTC P0683 pinpoint tests.
YesNo
GO to QB12.END test if no further glow plug DTC detected.
 

QB12 CHECK FOR OPEN IN DIAGNOSTIC LINE

Is the resistance greater than 5 ohms? (Typical resistance value is less than 1 ohm.)
YesNo
REPAIR open in circuit 1277 (WH/LG). RESTORE system. CLEAR DTCs and RETEST.GO to QB13.
 

QB13 CHECK FOR SHORT TO POWER IN DIAGNOSTIC LINE

Is the voltage greater than 5 volts? (Typical voltage should be 0 volts.)
YesNo
REPAIR short to power in circuit 1277 (WH/LG). RESTORE system. CLEAR DTCs and RETEST.GO to QB14.
 

QB14 CHECK FOR SHORT TO GROUND IN DIAGNOSTIC LINE

Is the voltage a constant 0 volts? (Diagnostic signal that is not shorted to ground is a pulse train; 0 volts - 12 volts.)
YesNo
REPAIR short to ground in circuit 1277 (WH/LG). RESTORE system. CLEAR DTCs and RETEST.GO to QB15.
 

QB15 CHECK GPCM CIRCUIT

Is the frequency in the range of 5 to 10 Hz? (Typical frequency for diagnostic signal with all plugs functioning is maximum 7 Hz. Typical frequency for the signal with one or more glow plugs failed is maximum 15 Hz.)
YesNo
INSTALL a new PCM. RESTORE system. CLEAR DTCs and RETEST.INSTALL a new GPCM. RESTORE system. CLEAR DTCs and RETEST.