I have a Komatsu Pc270LC-7L serial # A86309. Machine won't start with the key switch. Machine will start and run if you jump across the starter solenoid in battery box. It will shutoff with the key switch. When it's running, I have to connect a jumper to the battery relay for the throttle to work. When I check for power to the starter solenoid in the battery box, I have power on both terminals. 1 with key on and both with key in start position. Looking at the schematic, it looks like one should be ground. I am getting voltage to the key switch but don't seem to be getting power to the battery relay or the start solenoid in battery box. Ignition switch, battery relay and start solenoid have been replaced. I also pulled the small wire off alternator. I was told that if the alternator goes bad, it can send power to the start relay and cause it not to start because the controller thinks it's running and so won't allow starter engagement. Thanks in advance for any help.
Can you send a picture of the alternator. Do you have a schematic of the wiring. Worth getting for diagnosis. Think there is the safety relay on those that if it thinks the alternator is turning and outputting power it won't start. Simon C
I'm not around the machine. Somehow, it was getting power from the alternator side to the safety relay. Even though I disconnected the small wire from the alternator, it still wouldn't crank. I unhooked the wire at the safety relay and machine cranks off the key.
Not 100% sure, but disconnecting the wire at the safety relay will tell it the alternator is not running and it will crank to start. Problem is that it will start again if already running from what I understand. Safety, destroyed starter, problem then. If it runs then it would point to the alternator as being faulty unless there is a diode or something like that in between. Simon C
There is several diodes and I think that's what it is. The customer is going to sell the machine in a few weeks anyway. So as long as it starts and runs till then, it'll be fine.