2005 CAT D5N LGP Ignition Fuse Keeps Blowing??

[DozerDaddy66]

Ok dozer friends I am in desperate need of your help!
(This is my first time posting so I hope I’m doing it right. And forgive me but I’ve got a bit of a story to tell.)
So anyhow, I’ve got a D5N LGP Tractor Type dozer and boys she was running good with no trouble. Then one day this alarm starting going off and wouldn’t stop. I figured it was an electrical issue so I checked the wiring harness and most of the wires did not look great but a new wiring harness was gonna put a deep hole in my pocket so I ended up taking the seat completely out just to follow along and check all the wires. I finally messed around long enough until I somehow got the alarm to stop going off every time I started her up. Hallelujah!
Well, I pulled it forward and then backwards to make sure it wouldn’t go off again and it was all good, so I turned her back off. Tried to start her back up again not even 5 minutes later and she wouldn’t start at all, just kept blowing a fuse every time I try to start it.
After replacing the same fuse several times, my buddy said he thought it was a bad ignition switch. So, I coughed up almost $200 for a new one from CAT, drove all the way to go get it, brought it home and hooked it up, and boys I’m telling ya what, I’ll be darn if the daggone thang didn’t blow the same fuse again!
Every time I hook up the wire on the back of the new ignition switch, it just blows the ignition fuse every time!
Is there something else I’m missing? Now I’m not even sure what to try next! And listen here boys, I gotta get her running again and get back to work ASAP or else my ol’ lady is gonna jerk a new knot in my hide!!!
(Please help! She scares me.)
Any advice greatly appreciated.
Thanks!

 

[ahart]

First things first: need a serial number so we can get a schematic to you. Then we can isolate what circuit is shorted to ground causing your fuse to blow. The way I do it is find the connectors that wire goes through and start breaking the circuit down to find out exactly where the short is.

 

[DozerDaddy66]

Hi ahart and thanks for replying. I got this service info from the dozer. Hope it uploads correctly.

 

[ahart]

Schematic sent to you in PM

 

[ahart]

Im going to bring this back out to the world as I’m sure lots of folks here can assist.



Still down

Update: I finally got the schematic to open and I tried to follow your instructions as close as possible. I didn’t have a 24v ohm meter but I have a light up tester so I used it to check for power and I tested all the wires and inspected each one closely and I haven’t found anything unusual or out of place yet. I tried again several times to turn the master power switch on and before I even get it all the way to the on position it still blows the ignition fuse every single time, (and that’s with the ignition switch turned to the off position and all I did was start to turn the master power switch on.) This has been so frustrating guys I’m telling ya! I’ve had to work on and fix a lot of things on this dozer since I got it but man this has been the worst by far! This electrical crap is for the birds!!! I’ve got her stripped all the way down and still can’t figure it out. Meanwhile, my old lady has way BEYOND last all patience and she keeps giving me the death stare and threatening my very existence!! I’ve gotta do something fast but I know if I have to get a CAT mechanic out here it’s gonna cost me a small fortune!! But I’m at my wits end with this and have no clue what else to do. Any other suggestions greatly appreciated. Thanks! Need major help.

 

[ahart]

A couple of relevant points I see here.
•Any meter with ohms on it will work as continuity isn’t relative to voltage in a circuit that is not connected.
•you can use your test light to locate this issue if an ohm meter is not available, simply put your clip end on power and use the probe side on each side of the fuse to see where there is continuity to ground.
Once you have this info, you can go through the schematic and find the next connector you can test and check the wire on both sides of it to see where your short is. I would suggest unplugging the key switch to keep the rest of the machine isolated. You should be able to get the problem isolated down to a couple feet of harness easily as cat usually puts plenty of connections in their harnesses.

 

[Nige]

I know if I have to get a CAT mechanic out here it’s gonna cost me

IMHO you don't need a mechanic, Cat or otherwise. You have the electrical schematic, what you really need is a competent auto-electrician.