Good day Members, I am having some electrical issues that just came up out of no where. My excavator has always started very easily 1st time every time up until a couple days ago. I was running it for a few hours went to shut it off ( no issues ). However after maybe a minute the alarm is going off in the cab with oil pressure light. Had to discount the battery ground to stop the buzzer as the key was already off. Now when I try to start the machine it will attempt to crank, maybe a second and all power is gone. I disconnect the battery cables and the battery relay clicks. Put battery cables back, and then the same thing happens again. Batteries check good and have 25.5-26 volts. I checked the battery relay as per tech manual and it reads OK. Fuse's all check OK. Also key switch has been replaced by previous owner. I also tried removing cable to alternator to see if that made a difference. Looking for a place to start if anyone has had a similar occurrence. Thank you Chris
Welcome to the forum. One item that will really help you out is posting your machine serial number so the members here know which setup you have. When you say machine will attempt to crank, does it crank normally or weak? I've seen battery cables and grounds be weak that allow a second or two of weak cranking then heat up open breaking the circuit only to cool down and make weak contact again. This also causes bad voltages that cause havoc on the systems. Do you have the electrical schematics for your machine?
So, if your oil pressure light was going off, with key off, it had to get power from where it originates, which would probably be the starter solenoid terminal. Without a electric schematic, a guess would be that something is causing your starter solenoid to stay engaged or energized, without it cranking, so a bad relay? WAG.
Thank you for the welcome. Yes I do have the ser# ( P000110X020025 ) and also engine ser# ( T04045T706266 ). As for attempt to crank, it is full crank but cuts out almost instantly. I will look up and see if I have the electrical schematics, I believe I may have that. Thank you
@Geno78 Check your messages.
I will get on the the alternator circuit now and see if that is the issue. Thanks for the tip