This is probably a real longshot. But worth keeping in mind if things worsen for you. Even minor corrosion at the BCM connector can cause a multitude of unrelated symptoms. Here's the bulletin:
#09-06-03-004B: Intermittent No Crank/No Start, No Module Communication, MIL, Warning Lights, Vehicle Messages or DTCs Set by Various Control Modules (Disconnect Affected Connector and Apply Dielectric Lubricant) - (Sep 1, 2009)
Subject: Intermittent No Crank/No Start, No Module Communication, MIL, Warning Lights, Vehicle Messages or DTCs Set by Various Control Modules (Disconnect Affected Connector and Apply Dielectric Lubricant)
Models: 2005-2010 GM Passenger Cars and Trucks (including Saturn)
2005-2010 HUMMER H2, H3
2005-2009 Saab 9-7X
This bulletin is being revised to update the subject line and Condition information. Please discard Corporate Bulletin Number 09-06-03-004A (Section 06 - Engine).
Some customers may comment on any of the following conditions:
• An intermittent no crank/no start
• Intermittent malfunction indicator lamp (MIL) illumination
• Intermittent service lamp illumination
• Intermittent service message(s) being displayed
This condition may be caused by a buildup of nonconductive insulating oxidized debris known as fretting corrosion, occurring between two electrical contact surfaces. This may be caused by any of the following conditions:
• Thermal cycling
• Poor connection/terminal retention
• Micro motion
• 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.
Representative List of Control Modules
The following is only a representative list of control modules that may be affected by this condition and does not include every possible module 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 (ESC) Module
• Engine Control Module (ECM)
• Heating, Ventilation and Air Conditioning (HVAC) Control Module
• Inflatable Restraint Sensing and Diagnostic Module (SDM)
• Powertrain Control Module (PCM)
• Remote Control Door Lock Receiver (RCDLR)
• Transmission Control Module (TCM)
Important: DO NOT replace the control module, wiring or component for the following reasons:
• The condition is intermittent and cannot be duplicated.
• The condition is present and by disconnecting/reconnecting the connector the condition can no longer be duplicated.
Use the following procedure to correct the conditions listed above.
Install a scan tool and perform the Diagnostic System Check - Vehicle. Retrieve and record any existing history or current DTCs from all of the control modules (refer to SI).
⇒ If any DTC(s) are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle to identify the connector(s) of the control module/component which may be causing the condition (refer to SI).
⇒ If DTCs are not set, refer to Symptoms - Vehicle to identify the connector(s) of the control module/component which may be causing the condition (refer to SI).
When identified, use the appropriate DTC Diagnostics, Symptoms, Schematics, Component Connector End Views and Component Locator documents to locate and disconnect the affected harness connector(s) which are causing the condition.
Note: Fretting corrosion looks like little dark smudges on electrical terminals and appear where the actual electrical contact is being made. In less severe cases it may be unable to be seen or identified without the use of a magnifying glass.
Important: Use ONLY a clean nylon brush that is dedicated to the repair of the conditions in this bulletin.
DO NOT apply an excessive amount of dielectric lubricant 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 the harness side of the affected connector(s).
Reconnect 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.
⇒ If the condition can be duplicated, then follow the appropriate DTC, Symptom or Circuit/System Testing procedure (refer to SI).
Repair Order Documentation
Important: The following information MUST be documented on the repair order. Failure to do so may result in a chargeback.
• Customer vehicle condition.
• Was a Service Lamp or Service Message illuminated? If yes, specify which Service Lamp or Service Message.
• Was a DTC(s) set? If yes, specify which DTC(s) were set.
• After following the procedure contained within this bulletin, could the condition be duplicated?
⇒ If the condition was not duplicated, then document the affected module/component connector name and number on the repair order.
• If the condition was duplicated after the procedure contained within this bulletin was followed, and additional diagnosis led to the replacement of a module or component, the SI Document ID Number MUST be written on the repair order.