Its been awhile need some info on pc200lc-3 key switch can some one tell me what each post on the switch does and when? When I turn the switch on the battery relay does not work? You can put 24 v to the I think it was the BR post on key switch and the relay will work and you can start the eng . I have a wiring diagram but it does not show which post is hot and when. I can't figure out how the battery relay works for sure.
Is the battery relay in the positive cable to the starter or on the ground side? I don't know this particular machine, but generally these Japanese machines have the same terminals on the switches: B = Battery positive, should be hot all the time, even when nothing else is, but if the battery relay is in the ground side you have to test back to battery negative to get a correct result. Br =Battery relay, in any position but OFF this terminal will be hot to pull in the battery relay, it's just a master switch, same idea. Acc = This should be "Run" it's also on in all positions but OFF and powers up the instruments and if you have a fuel stop solenoid it's probably connected here. C = "Commencer" is all I can figure, British influence, we would say Start R1 = Preheat, comes on when you turn the key to the left of OFF R2 + also Preheat, but comes on when turn the key to Start. I think that's correct, from memory.
Thanks for the reply the BATTERY RELAY IS ON THE GROUND SIDE . When you turn the switch to the on position does the switch send 24v to the BR post and that is what energizes the battery relay?
Dash 3 excavators were always on the ground side. You should have one hot wire to the key switch all the time. Turning the key to on or pre-heat just grounds the circuit which closes the battery relay. That hot wire to the key switch comes directly from one of the small wires on the relay to a fuse on the fuse panel bar and then to the key switch. It is common on these machines to have harness issues, broken wires at connections and bad grounds. I've also seen my share of bad battery disconnect switches. The wiring diagram from Komatsu takes a bit to catch on to but once it implants a bit in your head it becomes easier to translate. As I recall the wires are color coded in the diagrams and not numbered. I used to use something pointy like a needle or punch to follow the wires out in the drawing to figure out where thing were going. If you have a service manual, there are sections in it that break down each circuit. Good Luck!
Yes, exactly.
Thanks for the reply's John c I'm going to need some luck. I have the manual on cd it has the wiring diagram but does not brake it down in sections. Its hard to follow when looking at the whole diagram wish it had the switch and battery relay circuit.
Ok I did a little checking on the switch I have 12v on post B, 24v on post BR and I think it was post RI had 24v this with the key off and used the neg post on battery as ground the one that goes to the battery relay. What do you think fuse panel or wiring? If I looked at the wiring diagram wright the fuse panel gets 24v straight from the battery to #1 fuse in fuse panel.
It sounds like you have a blown diode somewhere in the harness. As I recall they are down in the console under the key switch and just taped to the harness. You have to find in the wiring diagram which one goes into the battery and key circuit. They are numbered in the diagram and you will find a little white tag under the harness connector for each diode that will correspond to the number in the diagram. They are a pain to find. Komatsu doesn't get an arm and leg for the replacement diodes, just a couple of fingers.