Technical Service Bulletins

Intermittent no-crank/no-start GM

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Intermittent no-crank/no-start GM

This bulletin applies to 2005-2010 GM passenger cars and trucks (including Saturn), 2005-2010 Hummer H2 and H3, and 2005-2009 Saab 9-7X. Some customers may comment on any of the following conditions, where the technician may determine that he is unable to duplicate the intermittent condition:

* Intermittent no-crank/no-start

* Intermittent malfunction indicator lamp illumination

* Intermittent service lamp illumination

* Intermittent service message(s) being displayed

This condition may be caused by a buildup of non-conductive insulating oxidized debris known as fretting corrosion, occurring between two electrical contact surfaces of the connection or connector. This may be caused by vibration, thermal cycling, poor connection/terminal retention, micro-motion, and/or a connector, component or wiring harness not properly secured, resulting in movement.

On low current signal circuits, this condition may cause high resistance, resulting in intermittent connections. On high current power circuits, this condition may cause permanent increases in the resistance and may cause a device to become inoperative.

The following is only a representative list of control modules and components that may be affected by this connection or connector condition and does not include every possible module or component for every vehicle:

* Blower control module

* Body control module (BCM)

* Communication Interface Module (CIM)

* Cooling fan control module

* Electronic Brake Control Module (EBCM)

* Electronic Brake and Traction Control Module (EBTCM)

* Electronic Suspension Control module (ESC)

* Engine Control Module (ECM)

* Heating, Ventilation and Air Conditioning Control module (HVAC)

* Inflatable Restraint Sensing and Diagnostic Module (SDM)

*  Any air bag module

* Seatbelt Lap Anchor Pretensioner

* Seatbelt Retractor Pretensioner

* An SIR system connection or connector condition resulting in the following DTCs: B0015, B0016, B0019, B0020, B0022 or B0023

* Powertrain Control Module (PCM)

* Remote Control Door Lock Receiver (RCDLR)

* Transmission Control Module (TCM)

 Install a scan tool and perform the diagnostic system check. Retrieve and record any existing history or current DTCs from all of the control modules. If any DTCs are set, refer to the DTC list. When identified, use appropriate DTC diagnostics to locate and disconnect the affected harness connector(s) which are causing the condition.

Fretting corrosion looks like little dark smudges on electrical terminals and appear where actual electrical contact is being made. In less severe cases it may be difficult to see without the use of a magnifying glass.

Use only a clean nylon brush that is dedicated to the repair of the conditions. Do not apply an excessive amount of dielectric grease to the connectors, as hydrolock may result when attempting to mate the connectors.

With a one-inch nylon bristle brush, apply dielectric lubricant to both the module/component side and harness side of the affected connector(s). Re-connect the affected connector(s) and wipe away any excess lubricant that may be present.

Attempt to duplicate the condition by using the following information:

 * DTC diagnostic procedure

* Circuit/system description

* Conditions for running the DTC

* Conditions for setting the DTC

* Diagnostic aids

* Circuit/system verification

 If the condition cannot be duplicated, the repair is complete.




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