This month, we will discuss an often overlooked cause of loss of communication with a powertrain control module (PCM). Many techs have been trained to first check a non-communicating module for proper power feeds and grounds. In addition, techs were taught to verify defect-free communication wires to the PCM and check for short circuits in all the output solenoids the PCM controls. If all four of those requirements are met, they should replace the module.
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