Anyone ran into this or similar issue. Cat 277b cat0277btmdh00903 (thumb wheel didn’t work this morning after a bath under the cab last night, began checking things, starting it on and off, attempting repair, it lost power to the key/ instrument lights. Checked fuses, relays, main fuse, grounds. (turning the key fully to start kicks the fuel pump on) will crank over fine if given power to the starter, batt is good, not seeing any chaffed or bare wires. (Computers under 2 years old) also no power to the cat ET plug, but that was previously there.
I sent you the correct electrical schematic for your Serial Number. Best I can suggest is to start following power right from the battery in the direction of the starter motor and see where it disappears. You say nothing powers up with the key. At the key switch do you have incoming power on 106 Red.? it should be permanently present. If yes do you have outgoing power on 308 Yellow with the key in the on position.?
Currently getting it back to the shop. 308 has power with key on.
308 is the source of all switched power on the machine. If it is live with the key switch on the problem must be further downstream in the direction of the half of the fuse box that has the switched power circuits in it.
Problem found Update- With more chasing I found that the pins have become loose in the connectors to the fuse box. Crimping them down a little crooked with dielectric greas will get it by till new ends get put on. thanks