Cat 420D Electric Diagram Needed

[rshackleford]

You can check the pump, The current draw should be between 2 and 3.5 Amps. if the pump is bad it may be higher and then spiking and blowing the fuse.

it is defiantly pulling to many amps. it pulls about 9 amps.

The relay is wired to initially close from 304 and then power itself to keep itself closed from 327 through the relay and then 977.

do you agree that it isn't drawn as a latching relay?

 

[rshackleford]

i get it now!!!

it is not true latching relay. it is a self propagating circuit. once 327 hits and the relay closes it energizes yellow which is the coil.

 

[rshackleford]

without the diode this circuit would keep the starter running all the time.

i think we did have a bad lift pump out of the box.

 

[Lee-online]

without the diode this circuit would keep the starter running all the time.

i think we did have a bad lift pump out of the box.

Yes if the wires were connected. Without the diode the relay would not turn on.

Possible. Can you swap it with one from another 420.

 

[rshackleford]

Not sure if other 420 8# in yard. Might be on a job.

We pulled pump back out and hot wired it. It will not run.

Also we cannot hear pump pumping anymore when it was in the hoe. Also when it was in the hoe we opened fuel lines and it did not pump fuel.

 

[Lee-online]

Sound like the problem.

 

[willie59]

Sound like the problem.

That, and a pump pulling 9 amps is not normal.

 

[rshackleford]

i was gone from work yesterday, but i got a test message in the morning saying that the lift pump was replaced and the backhoe is in normal running condition.

so unless something changed throughout its use yesterday it was a bad lift pump out of the box.

thanks for all the help.

 

[Tedward]

I also need a schematic for the 420d. We recently replaced the alternator and batteries and now the lights wont work and the switch to remove the loader bucket does not operate. The fuses all are good.
Serial # is DCBLN01518

 

[tool_king]

Lee-online could you send me over the different wiring schmatics you have for the at 420d .My email is [email protected] That would a most helpful.

 

[YamYam]

Hi, I am also looking for the wiring diagram for my Father. He has written here he needs wiring for electric fuel pump relay wiring for 2004 420D cat backhoe can anyone help me out?

 

[Nige]

Need a machine Serial Number and an e-mail address to send the schematic.

 

[Bob/Ont]

Ok I understand why relay and diode are there now.

I think we have a bad primer pump again. Either bad out of box or old relay would sometimes keep pump running for extended times and it got burnt up. We jumper primer pump and blow ten amp p9 fuse after thirty seconds.

Have you changed the diode yet? It might be shorted on the side that shouldn't have continuity. Diode half way up the engine block.
Later Bob

 

[BBuddtec]

Hello All, Hate to revive an old thread, but short on time... got a 420e that blows the fuel fuse, isolated primer pump and lift pump, it will idle, but throttling up past about 12k rpm blows the fuse again... pulling my hair out!