New Diagnostic Strategy: Reprogram Control Modules Before Replacement

As Over-the-Air (OTA) updates and Vehicle-Wide-Programming become more commonplace on GM vehicles, a new diagnostic strategy is being implemented to better address performance concerns related to control module updates and replacements. Based on the latest data from the service engineering teams, the new strategy directs technicians to reprogram a control module with the latest software using SPS before replacing the module in all GM vehicles. (Fig. 1) If the updated software corrects the issue, no further repairs, including module replacement, are needed.

 

Fig. 1

 

The new diagnostic focus is reflected in updated Strategy-Based Diagnosis and Diagnostic System Check documents in Service Information.

Strategy-Based Diagnosis

The steps in Strategy-Based Diagnosis have been updated (Fig. 2) with the following:

Note: If a diagnostic procedure indicates to replace a programmable control module, the control module must be reprogrammed with the latest available software and retested before replacement:

• If updated control module software is available, reprogram the control module and re-test to verify if updated software has corrected the concern. If the updated software has corrected the concern, no further action is required; Do not replace the control module. If the concern persists after programming the control module with the latest software, continue following the diagnostic instructions.
• If updated control module software is not available, continue following the diagnostic instructions.
• If the scan tool is unable to communicate with the suspected control module, attempt to reestablish communication by removing and reconnecting power to the control module. This may be performed by removing the fuse or fuses powering the control module or by disconnecting the electrical connector(s) at the control module. If communication with the control module is reestablished after removing and reconnecting power, reprogram the control module with the latest software (if available) and re-examine the concern.

 

Fig. 2

 

Diagnostic System Check

Here is the new Updating Control Module Software information that can be found under Diagnostic System Check:

Control module software is an integral part of the operation and function of the control module. More than just the physical component, numerous corrections and enhancements can be changed in the software that will resolve many different faults. Service Information generally uses the term “software” as an indicator of a portion of the control module soft part that can be changed or updated; More specifically, this may be a boot loader, firmware, software, calibration, or other soft part.

As an overall strategy, reprogramming a control module with the most up-to-date software available is the correct diagnostic operation before replacing the control module. If a diagnostic procedure instructs to replace a control module, first determine if updated software is available. If it is, reprogram the control module with the latest software and retest the vehicle to determine if the fault is still present. Simply updating the software in a control module may resolve the concern without the cost or labor of replacing the control module. If programming the control module with the latest software corrects the concern, take no further action. If new software does not resolve the concern or if the control module already has the latest and most up-to-date software, continue with the corrective action identified in the diagnostic procedure.

For more details on the new diagnostic strategy, refer to the appropriate Service Information.

– Thanks to Mike Waszczenko