The TB135 excavator I’m working on is suck on. Meaning the machine thinks the key is in the run position when it is in the off position. I have tested the ignition switch and it is correct, even with the ignition switch unplugged the machine continues to be on with the fuel pump running and the gauge cluster lit up. The only way to turn it off is to disconnect the battery or pull fuses. So far I’ve partially removed the wiring harness and tested all the relays and diodes i could find. I’m thinking the wiring harness is bad somewhere and there is a short to power between a 12v batt wire and the machine run wire. The other thing I was thinking it could be was that a relay is stuck on and not de-energizing, but I haven’t been able to find a faulty relay so far and I think I’ve tested all of them. Do you guys have any ideas before I commit to pulling the wiring harness completely out to inspect/ replace it? Whatever is wrong with this thing I’m sure its going to be something dumb that I should have seen earlier Ill answer any questions you have and I’ve attached the wiring harness for the machine. Thanks -Pete
Pulled the "line relay"?
I can't find the fuel pump or wiring in that schematic. Check all 3 of these diodes.
I have tested all the diodes and relays in this group (under the left joystick) Also attached is a map of the wiring harness because while i can read the wiring harness i dont know where the components are in relation to the machine
My tb250 started to stay running after I replaced the fuel shut off solenoid unless the throttle is all the way down, I’ll be putting the old solenoid back on this weekend since my issue is something else. not sure if that is helpful, but perhaps another area to look at.
when you pull fuses which fuse is it that finally gets the machine to turn off? That is the circuit you need to check
I've attached pictures of the fuses that turn it off and the one relay that turns it off.
The fuse you're pointing to (actually that whole column of six), is energized by the line relay (circled), which appears to be controlled solely by the stop timer (in square, #12)
When I disconnect that timer the machine stays on.
Looking further, the alternator looks to have a say in this. Can you unplug the connector on the back of the alternator and retry? The big red wire can remain connected.
Unplugging the alternator doesn’t change anything.