Hello all,

I had a squirrel decide to chew on some electrical wiring on my truck '03 2500HD LT duramax last night. I now get a code P0540 which is the Intake air heater circuit, and a code U1800 which is CAN bus communication. I looked under the hood, and two yellow wires were chewed through on the top delphi connector on the driver's side of the engine compartment. I checked the resistance between the pairs of wires, and the two yellow ones on the engine side showed 660 ohms, and the two yellow ones on the ECM side read 41K ohms, with both being grounds with the vehicle off. The wires coming out the back of the delphi are yellow on the left wire and a higher gauge tan coming off the yellow wire on the right. If anyone has the Factory Service Manual or any general knowledge of which wire goes to which wire I would be greatly appreciative. I'm attaching two pictures of the wires in question. My guess is they are interchangable, or the thicker base of the one cut wire probably goes to the one on the right with the thicker gauge tan wire in the back. And also, any good ideas on how to kill squirrels that keep getting under the hood? I had another one die on top of my turbo a couple weeks ago. That burned him pretty good. :)

Hello all,

I had a squirrel decide to chew on some electrical wiring on my truck '03 2500HD LT duramax last night. I now get a code P0540 which is the Intake air heater circuit, and a code U1800 which is CAN bus communication. I looked under the hood, and two yellow wires were chewed through on the top delphi connector on the driver's side of the engine compartment. I checked the resistance between the pairs of wires, and the two yellow ones on the engine side showed 660 ohms, and the two yellow ones on the ECM side read 41K ohms, with both being grounds with the vehicle off. The wires coming out the back of the delphi are yellow on the left wire and a higher gauge tan coming off the yellow wire on the right. If anyone has the Factory Service Manual or any general knowledge of which wire goes to which wire I would be greatly appreciative. I'm attaching two pictures of the wires in question. My guess is they are interchangable, or the thicker base of the one cut wire probably goes to the one on the right with the thicker gauge tan wire in the back. And also, any good ideas on how to kill squirrels that keep getting under the hood? I had another one die on top of my turbo a couple weeks ago. That burned him pretty good. :)

Bird feeder and a .22. I'll go cap one right now just for you buddy. :D

Other than just going by wire size and jumping them together.
Which could cause more issues. (I'd do it. But it's not my truck.)

Try looking here.
http://www.gmupfitter.com/publicat/2004_BB/2003_Beyond_LD_Electric_CK.pdf
It's helped me in the past.
Down into the 60's ish is the good info on pins.

Bird feeder and a .22. I'll go cap one right now just for you buddy. :D
lol yeah I wish our neighborhood had feral cats. They keep everything in check. :) I am thinking about getting a weapon just for this occasion. My .243 may not be the most stealth option in the middle of Minneapolis though... haha

I have searched that manual which a link was provided to and it does show a yellow wire going to the Intake Air Heater. That narrows it down. haha I wish I knew if the other yellow wire came from. I may have to track the pins on the ecm to do this correctly, however. Does anyone else possess intimate knowledge of this wiring harness?

There are one stroke pellet guns that shoot over 1200 fps but it is a one shot deal and you have to see them and hit them without shooting your truck. Have a heart traps work well but you then have to "move em" some place else or give em swimming lessons:D but the trap is there 24hours a day to get em. Avoid poison as you might get other animals or a dead critter stinking up your truck or house.

There are one stroke pellet guns that shoot over 1200 fps but it is a one shot deal and you have to see them and hit them without shooting your truck. Have a heart traps work well but you then have to "move em" some place else or give em swimming lessons:D but the trap is there 24hours a day to get em. Avoid poison as you might get other animals or a dead critter stinking up your truck or house.

Yeah, I hear ya. I already had one bite the dust on top of my engine. I don't know why they like it so much. A couple weeks ago they chewed the heck out of my hood insulation and I found the critter burned to a crisp back by the wastegate. Apparently one of his buddies wants revenge. Any ideas on the CAN bus error? I didn't see any other compromised wires other than these two, so I'm hoping one is x and the other is y.

Update: The thicker yellow wire is actually yellow and black. Otherwise I still have no leads as to what it is for. Any help would be appreciated!

Check this thread:

http://www.dieselplace.com/forum/showthread.php?t=374316


Maybe he has a diagram you could use?

Check this thread:

http://www.dieselplace.com/forum/showthread.php?t=374316


Maybe he has a diagram you could use?

I sent him a PM. We'll see if he has anything. I'm hoping to get this nipped in the bud tonight. Gotta travel 340 miles round trip tomorrow afternoon. :)

So i looked at the diagrams but idk. , but here the wiring diagrams anyway hope u can fix ur truck.

Ok... So the solution is at hand. I took the ECM out of the vehicle and traced the wires to pin numbers on the ECM to solve the dilemma. Here is the answer:

The yellow wire on the left at the delphi connector is for the CAN bus, which can be found on C1 (blue) pin #10. The wire is EM shielded, which is why it gets thicker for no reason a couple inches down from the connector.

The yellow wire on the right is the signal reference for the Intake Heater, found at C1 (blue) pin #29.

Be aware that you will need to clear the ECM codes to get rid of all of the CAN bus errors, since I did a continuity test through all sorts of modules and I'm sure they weren't happy with me. It took two clears and a bit of driving to nix them all. :)

:eek: Holy crap, you were up a bit late working on that...

Good to see you got it handled.


Cool to see liftedduramax02 came thru quickly with some diagrams, kudos to him. The sharing of info on this site is what makes it so valuable.

I use poison pellets in my shop. Put them out on high shelves so only those who are supposed to get it do. Haven't had any dead ones in the shop but the pellets are eaten. Guess they get thirsty as hell and head for the lake.

I do love this site. Everyone comes together to help one another out. Gotta love that! aka108, what kind of poison pellets do you buy? Are they squirrel specific or will they kill all rodents? :) Either way, sounds like that will be enforced along with my pellet rifle being right by my side for quick efficient dispatch of squirrels...

How are they getting up in there so far!

How are they getting up in there so far!

I think this is war. They chewed two more wires on the same connector today. Thankfully these are different colors so I don't have to guess, but I guess I found a weekend project. I'm gonna have to install fencing on the underside of the truck so they can't get in. This is just ridiculous. I will also need to go and eradicate the problem. Where does one get "have a heart" traps anyhow?

I think this is war. They chewed two more wires on the same connector today. Thankfully these are different colors so I don't have to guess, but I guess I found a weekend project. I'm gonna have to install fencing on the underside of the truck so they can't get in. This is just ridiculous. I will also need to go and eradicate the problem. Where does one get "have a heart" traps anyhow?

Tractor supply has them.

Where do you get the poison pellets?

I picked up a Havahart trap from Menard's. It should assist me in giving those little tree rats some swimming lessons. It shall be my greatest pleasure to watch them drown in a slow, agonizing way. Dick Cheney would blush at what I endeavor to do to these wretched critters for messing my my truck! I don't know if they make squirrel specific poisons. I understand their internal chemistry renders typical rat poison ineffective on them. But if anyone has any, by all means do let me know what it is called and where it can be obtained!

Kinda sick dude.

Kinda sick dude.

LOL. Just don't between a man and his truck I guess. I'm just messin'. I intend to give them swimming lessons, but I won't torture them any more than is necessary to snuff out their life.

Not sure if this would help the swimming lessons but I have strange idea. At a local Agway, I saw that they had Coyote piss along with fox pee in a bottle. I asked what in the heck for and she said it was to scare off critters. I would try a small amount near the truck or on a tire so the smell won't get in the cab. I have an old 76 chevy lot truck for plowing and moving fire wood, I had alot of mice moving in and stinking the truck up really bad so I put cat fur from my cat in the cab and under the hood and that ended it. But I did give the cat an over night stay in the truck as well. Good luck and let us know how the squirrel high dive contest goes.

Good call on the predator scent. My girlfriend picked up some spray that accomplishes the same thing and I sprayed that in my wheel wells. My trap caught one tree rat this morning. I felt nice and released him in a park about 5 miles away. The next one may not be so lucky. My cats were begging to have a crack at him when I brought the cage up to them. I'm gonna keep trapping the little guys till I can go a day without catching one.