Came across this site looking for a wiring diagram for my 420d cat backhoe (BLN). Wondering if anyone can help me out with a wiring diagram. I was airing up the seat and it just died. It did this once before but it restarted right away. This time there is a buzzing/squeeling when you turn on the key then when you turn to start the starter/relay just kicks in and out real fast, but starter does not turn engine, the radio quits and the gauges and work lights don't work . Fuses all good, one relay was buzzing. Battery volts staying up around 12.7 when troubles happen. Wiring digram would help alot, Thank's.
Sounds a lot like a loose main cable from batteries to starter or ground. Have you checked voltage to the main cables at the starter while trying to start it. We need the full serial number. There is a break at bln10299
Thank's, BLN01496. Going to look at it again this morning in the day light. will check the main cables first.
Check your email. I just sent you a message.
Got it running and the gauges all went back to normal readings. I cleaned the starter terminals, all the main power points. had a good charge on it all night. Just for diagnoses I hit the seat pump button and it quit instantly. It did restart right away but fuel gauge peged as well as tach, engine cold but temp gauge at half again. Must be a bad connection, wire or ground causing backfeed through gauges. Pulled out seat fuse for the mean time. Thanks for the schematic, going through it now.
If it's the seat suspension control switch that's giving the problem it ought to be relatively simple to track down. I can't see the circuit it controls being that complicated.
Got it figured out. A ground wire/wires #200, common to all those gauges and seat had a loose nut on their ground stud. Cleaned up the corrosion, tightened it back up. Everything's good. Ground stud was right under fuse block. Thank's for the help. Anyone know if there is an updated thermostat housing for that machine?
There was a change in the earlier serial number engines but yours is 7BJ51755 so you already have the latest design as far as I see.