Back story: 1) Welder was hired to weld exhaust on machine. 2)Debris of years of leaks and leaves etc. catches fire during process. 3)under hood of machine goes up in flames while welder’s ass slowly heats up whilst sitting on hood. 4) Put fire out and discover main harness burnt, melted into a big glob of goo. Hydraulic hosejackets burnt off, some motor wiring burnt as well. 5) Electromechanical guy (me) gets called in to save the day. I spliced, soldered and heat shrunk repaired dozens of wires. Fortunately for the most part, Hitachi had good color coding to help. However, there were a few wires that shared colors that in my opinion caused our issues. Duplicate solid reds, yellow and white red. Upon trying out the EC motor hummed very loud causing me to look into miswires even deeper. All things aside, I believe we took out the EC controller and/or motor and position sensor. I have replaced the motor and sensor through SOME t-shooting but then discovered the issue was likely in the wiring. BEFORE I INSTALL THE NEW EC Controller, I have to address this wiring issue. Working my way through a very over complicated design to say the least. the EC stepper motor is equipped with 4 wires ( red, yel, org, and brn.) as described in service literature. Also in the same literature is a pictorial showing these 4 wires going back to the EC control module at pin #s 104red, 108 yel, 107org and 103 brn. part of the t shooting involves checking continuity of these four wires. During this, I discovered that the harness plug ON THE EC MOTOR matches the color code as it should. However, the WIRING HARNESS PLUG that plugs into it is red,yellow, white/red and blue/yellow. Yet back at the EC module wiring harness plug they are once again red, yellow, orange and brown. I have an open circuit on my orange wire. Where in the loom does it turn color. Does it stop at a certain component on the way back to the controller? confused as the documentation all show a direct link. Somewhere in the harness the FROM THE MOTOR PLUG, TO THE CAB MODULE, the white/red turns to the brown and the blue/yellow turns to orange. Nothing like this is shown on any parts of the documentation. Have it over looked something in my troubleshooting?
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