86Marlboro
Member
Working on a 2012 Mack GU713 SN: 1M2AX04Y4CM011138. I had some comm issues, where I couldn't connect to the ECM via JPRO or PTT. Made a bench harness to verify integrity of the ECM and it connected flawlessly. Therefore, my issue is in the wires. I have measured and checked the voltage in my comm link plug and found that Pin G with coincides with ECM A 33 is the problematic circuit. It seems to have a dead short to ground given a continuity sound test with my multimeter. it also has about 8.0 Ohm resistance between Ping G and the negative terminal on the battery. I have isolated the issue so somewhere within the cab I believe. I have disconnected the large plug on the firewall, as well as the other cannon plugs, etc. The tone is still prevalent and resistances do not change. Therefore, my issue is somewhere in the cab harness or internally in a ecu within the cab.
Any assistance in moving forward? I'm pretty much at a dead end. I unplugged the dashboard and VECU and the resistance did not change. So, im thinking its internally in the harness. But, wanted to get a second opinion before I started ripping harness and cab apart. Any help is appreciated, I'm all ears and open to any ideas. Thanks in advance!
Will post notes below.
Any assistance in moving forward? I'm pretty much at a dead end. I unplugged the dashboard and VECU and the resistance did not change. So, im thinking its internally in the harness. But, wanted to get a second opinion before I started ripping harness and cab apart. Any help is appreciated, I'm all ears and open to any ideas. Thanks in advance!
Will post notes below.
