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Service Information
2007 Chevrolet Silverado - 4WD |
Sierra, Silverado VIN C/K Service Manual | Document ID: 2549100
#PIP3586G: Diesel Engine Glow Plugs Trouble Codes - (Dec 1, 2010)
Subject:
Models: 2006-2010 Chevrolet Express, Kodiak, Silverado 2006-2007 Silverado Classic 2006-2010 GMC Savana, Sierra, Topkick 2006-2007 GMC Sierra Classic Equipped with the 6.6L Diesel Engine RPO LBZ, LLY, or LMM This PI was superseded to add pictures. Please discard PIP3586F.
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Condition/Concern: A dealer may encounter a customer concern of the SES light on, a Glow Plug Control Module (GPCM) DTC, or individual cylinder glow plug DTCs.
A loose battery feed connection at the battery, starter, alternator, or the Glow Plug Control Module (GPCM) may induce glow plug concerns. This PI will describe and assist with concerns related to GPCM and/or Glow Plug DTCs.
Recommendation/Instructions: The first portion of this PI will discuss GPCM diagnostics and repairs.
If a vehicle has been brought in with GPCM concerns or DTC P064C the GPCM battery positive cable will need to be inspected. Inspect for loose connections at the GPCM Connector (squeeze type terminal number C1 or X1) and at the power source/mega fuse. If the squeeze type terminal is damaged, the complete cable would need replaced. If the GPCM terminal is damaged, the GPCM would need replaced. Retorque loose mega fuse/power source connections using current SI specifications. The ignition voltage supply from the under hood fuse block must be consistent. Loss of voltage from the under hood fuse block may induce a P064C.
Note: The source or main power feed to the GPCM differs depending on the vehicle being serviced. Use the current SI power feed distribution schematics for power feed location.
If a 2007-2008 GMT900 C/K truck has DTC P064C, and both ends of the main power feed terminal have been inspected it's possible to have a cable crimping concern. The crimp may not make a positive This PI was superseded to add pictures. Please discard PIP3586F. connection, and will not be easily detected. If necessary replace the GPCM Battery Positive Cable on 2007-2008 GMT900 C/K trucks.
Evaluate DTC P064C after connections are inspected and repaired. Complete the following steps twice to see if P064C resets
Start the engine let the engine run for at least 2 minutes, turn the ignition off for at least 2 minutes, and then restart the engine to verify P064C has not returned. If P064C resets after all connections have been repaired (GPCM has NOT been replaced yet) replace the GPCM.
This section of the PI discusses Glow Plug diagnostics and repairs.
Glow plug circuit DTCs P0671-P0678 may be caused by an out-of-tolerance glow plug resistance. During the individual glow plug replacement inspect the glow plug tip for damage. Only replace the individual glow plug (related to circuit code) unless there is damage to the glow plug tip. Compare the glow plug damage to the two pictures found below. If the tip of the glow plug is missing (figure 1) or there is external damage to the glow plug tip (figure 2), replace all eight glow plugs.
Figure 1
Figure 2
If any of the glow plug tips are missing, the cylinder head must be removed. All debris must be removed from the cylinder. When the tip of a glow plug enters the cylinder, engine damage may occur. Make any engine mechanical repairs as needed.
There are certain electrical concerns that may induce the glow plug to go open. If the glow plug system senses a certain electrical "noise" on the power feed, it could induce glow plug concerns. This electrical "noise" may be induced by jump starting, loose connections, disconnecting the batteries with the ignition in the ON position, or a battery charger being used during a module reprogramming event.
Complete all electrical circuit inspections and engine repairs as described. On 2006 model year vehicles be sure the updated calibration was installed into the GPCM per Campaign 06522. After installing the new GPCM software, complete the Fuel Injector Flow Rate Programming following SI procedures.
Note: Do not replace the GPCM for any one or combination of the following internal open glow plug codes: P0671, P0672, P0673, P0674, P0675, P0676, P0677 or P0678 when not accompanied by GPCM Diagnostic Trouble Codes. GPCMs have been returned and inspected with no problem found.
Note: Aftermarket Add-on remote starter or alarm kits must be removed before any glow plugs are replaced. Interruptions to normal starting procedures may induce glow plug concerns.
Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.
GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.
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