Vehicle: 2009 GMC Acadia, FWD, V6-3.6L, Automatic Transmission/Transaxle
Problem: The Acadia was towed to the shop for a no-start/does not crank concern
Case Details: The technician attempted to scan for diagnostic trouble codes (DTCs) but found no communication with the engine control module (ECM). He checked for battery power to the ECM. There was none. The technician found that the ECM1 fuse (15A) was blown. He replaced the fuse, but as soon as he turned the ignition key to the ON position, the fuse blew again.
Using the factory wiring diagram in ALLDATA as a guide, he found the only power supply to the ECM1 fuse was from the ECM itself. He unplugged the ECM and replaced the fuse. This time, turning the ignition switch to the ON position did not blow the fuse. He load-tested the circuits, between the ECM and ECM1 fuse. They all passed. He determined that the ECM must have been shorted internally.
Confirmed Repair: The technician replaced and programmed the ECM. After that, the Acadia cranked, started and ran great… and the ECM communicated normally. Problem solved!
The ALLDATA Tech-Assist team fields cases like this every day. See how Tech-Assist can help your shop save time and money with on-call diagnostic support from ASE-certified Master Technicians. More Tech Tips
Not an ALLDATA customer? For access to this valuable experience-based repair data and reliable OEM information, start a free trial today.
If you would like to read more articles like this one please subscribe to ALLDATA News.