Komatsu WA1200 Loader Transmission fault codes

Hey guys, im hoping someone works in the mining industry and could help me out and could throw me some ideas. We got a machine that has been down for a big customer here in Australia for over a week now. I had a look at the machine after about the 5th day it had been down so it has been through some hands looking at the machine before they called us. Currently i am off at the moment and got my off sider at the machine now and really want to know what is wrong with it plus we are OEM auto electricians so its not a good look TBH if we cannot fix it. Long story short the TCM is bringing up active codes that shoudln't allow the machine to travel as well as a few other codes that checked out ok. I ended up calling a TCM after being on it all day and was a bad call. here is a story if anyone has time to read. cheers to whoever does, much appreciated.

The story goes, the machine came in to get the starter motors replaced then it went back to work for a few days. All of a sudden these transmission faults ocurred. The customer auto electrician on the mine site noticed the fan cab pressurizer was running whilst the key was off (should only be on with key power), so the whole cab was powered up with the key off. Apparently they traced it down to be the park brake switch circuit. ran a new wire and fixed that issue. Then another technician decided to remove when I got there as he thought it wasn't eliminating the issue.I ended up disconnecting the transmission ECM (TCM). This corrected the key power issue, then I re-connected the TCM and the key power issue was completely gone, it did not fault all day. At this stage I was a bit bamboozled so I checked powers, grounds, key power and sensor supply circuits just for good measure at the TCM. All was ok. Then started tackling some of the transmission code issues.

There was a lot of tail chasing due to new and old fault codes intermittently faulting. Some of the codes that we checked were: DKA0L0 boom angle sensor hot short, 15SELH ECMV(1) Fill switch circuit disconnect and DLE2LC Engine speed sensor short circuit. All these checked out ok except for the engine speed sensor fault. If you read the flow chart it says that the engine speed sensor has a ground fault but we were getting a signal back to the TCM as well as RPM on the dash and in the monitor. I then Checked the speed sensor under the cab and found an open circuit, ran a new wire directly to the TCM and still didn’t fix the fault.

We took it for a test drive monitored a few things and just cant explain why some of the codes in the operator mode wont clear and are not in the service mode failure history. The codes present in the operator mode would only become active when actually operating the machine. The codes in the operator mode indicate that the machine should not be able to drive but could not fault it. 

 



 

with those codes being intermittent I would be looking at wiring and look for chaffing of harness at bend points.