My dozer is on the blink. It was working and on ocassion it would throw a code and not move.let it set for awhile and we'd go again. Now it shows F9C3 code and will not move. Have power to TCU but no green lights or red. If it is in fact the TCU any leads on where to get one or try to have mine fixed if fixable? Also any way to know for sure that's it by testing, I'm going to take one off a 550 tomorrow and see if it will work. I know it won't be calibrated the same but should tell me if mine is bad or am I wrong?
C&C Equipment on You Tube has a video on soldering in new Capacitors on one and it was good to go after that. Not saying it is your problem, but watch it and then see if yours is similar. Simon C
Did you check the TCU's ground connection?
Got a good clean ground. Just drop in voltage now
Sounds like the TCU is definitely a suspect, especially if you've got power to it but no lights at all. Swapping in the TCU from the 550 is a good test—calibration differences shouldn't stop it from at least powering up and helping confirm whether your original unit is dead. Before condemning it, double-check grounds, connectors, and power under load. If the borrowed TCU wakes everything up, you'll have a pretty good answer. As for repairs, some electronic control module repair shops can rebuild TCUs, so it may be worth checking before hunting down a replacement.