Itiswhatitis
Member
Hi... Cat electrial expert needed!!! I have a head scratcher of an electrical fault on a 312d, lost power to the swing brake, 2speed travel and pump solenoids.. Any help would be great 
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Cat electrical fault
- Thread starter Itiswhatitis
- Start date
Welcome to the forum.
Usually problems like this need methodical troubleshooting and to go in randomly doing stuff can be a mistake. But here's a little shortcut anyway;
First check your grounding points. Trace the harness back from the pumps and swing box towards the EPC (Engine/pump controller) and somewhere on the way you'll find a load of black wires grounded to the frame.
Next check the fuses to see if the EPC is getting its power supply. It will have at least two and maybe three fuses supplying permanent battery power and switched ignition power. It will power up with only one, but needs need them all in order to work properly.
And please, if this helps you fix your problem, come back, let us know and join in the forum. It pisses me off somewhat when people ask for advice then do a runner.
Usually problems like this need methodical troubleshooting and to go in randomly doing stuff can be a mistake. But here's a little shortcut anyway;
First check your grounding points. Trace the harness back from the pumps and swing box towards the EPC (Engine/pump controller) and somewhere on the way you'll find a load of black wires grounded to the frame.
Next check the fuses to see if the EPC is getting its power supply. It will have at least two and maybe three fuses supplying permanent battery power and switched ignition power. It will power up with only one, but needs need them all in order to work properly.
And please, if this helps you fix your problem, come back, let us know and join in the forum. It pisses me off somewhat when people ask for advice then do a runner.
Itiswhatitis
Member
Thank you for your reply. I'm new to forums but shall be a regular. I've found all the earths, cleaned and checked continuity... All good. It's a voltage issue, only getting between 2-4 volts and should be 24. Can't seem to find where those 3 circuits take the power from. Done an ecu swap as told by cat n not that.
. I've found all the earths, cleaned and checked continuity... All good. It's a voltage issue, only getting between 2-4 volts and should be 24. Can't seem to find where those 3 circuits take the power from. Done an ecu swap as told by cat n not that.
Nige
Senior Member
If you would like an Electrical Schematic for the machine then PM me your Serial Number and email address. I think you need 3 posts before you can send PMs so make one more and the PM button should activate.
Itiswhatitis
Member
Sweet.... I'll get posting
Thank you for your reply. I'm new to forums but shall be a regular
They're powered direct from the EPC. Are you sure that you're getting 24v at all the the inputs?
excavator
Senior Member
Thanks for all the help you give us Nige. I agree 100 percent with your comments about not responding back with results. I feel the same way, but then I have to admit that there have been times that I to have gotten the problem fixed and continued on with life, totally forgetting to post the results. So if I have done that to anyone here on HEF please accept my apologies. It was not intended but simply an oversight.
Itiswhatitis
Member
Nige pm'd.... Thanks. Cmark thanks for your input mate.. I got a feeling its going to be a real easy but obscure fix, hope so cos I'll kick myself sore if I've missed something really simple. I've been through the battery compartment, cab fuse box and wiring. Really need to know what to expect at the ecu wiring plugs and term no's. I have got a workaround but I'd rather get to the bottom of it.. I think like most on here, hate being beaten by a machine lol
Nige
Senior Member
You have mail mate.
Itiswhatitis
Member
Thanks Nige.. I'll let you know of the outcome.
Itiswhatitis
Member
hey folks... a bit of an update. After a day of tracing wiring and testing I decided to call in our local Cat dealer. Apparently the turbos not working??? I was not in today when the engineer called so I'll get the full rundown tomorrow.. the original problem was the slew brake, 2 speed travel and powershift solenoids, what the turbos got to do with it is beyond me
Nige
Senior Member
I will certainly be interested to hear Finning's explanation of that one ................
Dad5
Well-Known Member
Check the pressure switch in that circuit. Its an input to the computer. It will pass an ohm meter test but won't carry enough current.
Itiswhatitis
Member
I'm pretty new to the world of cats and all help has been great... Forum newbie and gonna be a regular. Turbo stripped and yes damaged but not enough to cause 3 electical problems haha sorry my English sarcasm not convinced but will put a new one on and see.
not convinced but will put a new one on and see.Mjrdude1
Well-Known Member
Cat troubleshooting procedure:
Arrive at customer location, check.
Troubleshoot everything not related to the problem for additional revenues, check.
Look into the problem with electrical system, find broken wire or bad fuse (not enuf revenue to justify travel time), blame bad turbo for low power and unresponsive circuits, check.
J/K lol
Arrive at customer location, check.
Troubleshoot everything not related to the problem for additional revenues, check.
Look into the problem with electrical system, find broken wire or bad fuse (not enuf revenue to justify travel time), blame bad turbo for low power and unresponsive circuits, check.
J/K lol