getting power into camper/trailer wiring harness

[akrockhound]

I have an '03 2500HD/Ex Cab with the Duramax.

It came pre-wired with the trailer wiring harness and the camper/5th wheel harness.

There's no 12V+ power in the red "power feed" wire in either harness. I have been told that usually there isn't until you put a fuse into the appropriate vacant fuse slot in one of the fuse boxes.

After studying the owner's manual and the fuse boxes and asking the local RV equipment installer we can't find the appropriate vacant fuse slot.

The dealer is'nt much help but I have another call into them

Anyone dealt with this on a similar '03?????

[ 06-02-2003, 01:42 PM: Message edited by: akrockhound ]

[SS396]

Arockhound,

You should have a red plug in place of a fuse in the B+ Stud#1 slot. Replace that with a 40A fuse and you should be able to power both harnesses.

You can get the fuse at NAPA part# 782-2044, other parts houses may have it also. Most dealers have no clue about the problem or the fuse.

[akrockhound]

When I remove the red plug from stud#1 I see two blades (compared to 2 slots in a normal fuse socket)

Does this sound right????I should buy a fuse that has 2 slots to fit over the two blades in location Stud #1??

I finally got a call into the Chevy dealer and to the service guy who "knows about all this stuff"...You were right he didn't have a clue...Do I want these guys to work on my truck????Jeez

[SS396]

Yes that's right, the fuse will fit over the blades.

[akrockhound]

to SS396

Dealer has confirmed your solution

trouble is at the dealership we used a multitester and there's no vlotage across the 2 blades after removing the plastic cover for Stud#1.(with or without the turck running) Geez this is frustrating

Suppose we have to go deeper and hook up the red wire somewhere?????

[Brnorm54]

I am in in a similar situation with my new 03. I have no accessorie power out the back. Mine did not come with the fifth wheel harness. I have a long enough fifth wheel harness to run down to the back. After learning about the change in the 03 on here, I switched pins A and D on my 01 brake controller harness and everything works ok, except no power to the 12 volt lead out the back. Went to napa and ordered the green 40 amp new style fuse to put in the #1 slot in place of the dummy red b+ plastic one. Was in napa today and picked up the new fuse. Got an extra one. Pulled the red dummy out and put in the new 40 in Pin #1 , and it immediately blew the fuse. So now what? Anybody got any suggestions?

[DonG]

akrockhound, Brnorm54,

What you guys did is exactly what I did, but my o3 worked correctly. There should be power to stud #1 in the upper left as you look at the fuse box from the drivers side of the truck. You need the dealer to track down the problem.

Brnorm54, did you have the trailer plugged in when you inserted the fuse? If not, then the dealer needs to solve it. If yes, maybe it is a problem with the trailer.

Good Luck, Don

[Brnorm54]

Trailer was not plugged in when fuse blew.

[BigLakeDMAX]

Rockhound: You should not see a voltage across the two blades of stud 1. You should see 12v from one of the blades (the powered one) to a ground. If the meter did indicate voltage across the blades, that would indicate a short in the wire to the rear of the truck - likely what brnorm54 would see with his, based on his post. I'm assuming your dealer tried a fuse and still no power? That would indicate a connection problem in the power center/fuse box.

Brnorm - if your trailer wasn't connected and if you've done no additions or modifications to the trailer wiring harness on your truck, I'd have them fix it under warranty. Otherwise, the wire runs inside a black loom directly from the power center under your hood, along the left side frame rail, back to the connector by your hitch. Somewhere in there the wire is likely shorted. I would first check the connector and then run the wire from back to front. Before opening the loom, look for obvious intrusion into the cable by a bolt or screw, or for a pinched or damaged portion.

An additional bit of info I learned the hard way last week - the trailer running, turn signal, and brake lights are powered by separate fuses located in the same power center. I couldn't figure out why the right running and tail lamps on my truck worked while the one on the 5'er didn't. Got out my meter, spent time checking my wiring connections, etc. before finding this out. Replaced the trailer RH tail lamp fuse with the spare in the box and away we went.

Good luck to both of you!

Don

[akrockhound]

Dear BigLake DMAX
thanks nothing like a little pilot error when using the multitestor. I felt like Homer Simpson when a litght went off in my head and I realized I shouldn't get 12v across the blades. dooohhh!

I now have the fuse (40A) installed and have power to harnesses.

Since the 12 power feed does not have an isolator I have installed a selonoid in the camper wire harness under the front (driver's side) corner of the truck bed. I spliced into the brown (running lts) wire to drive the selonid switch. So whenever my driving lights are on then I am charging the camper battery and when I'm parked the camper/truck batteries are isolated

[Brnorm54]

Found the problem! Thought I didn't have the fifth wheel harness,but I do. Found it all tied up and pinched between the rubber isolater and the frame up between the cab and the front left side of the box. No doubt somebody was sleeping at the factory when she went together. Headed to the dealer tommorrow to have them warranty it. Tested it again at the rear connector and the running lights are now gone. Surprised it isn't affecting more. Thanks BigLakeDMAX for headin me in the right direction on this.

[SparkyTX]

Thanks for the info on this, guys! I just got my 03 a week or so ago. I said something to the dealer about a 40A fuse for trailering, as I had read something on here. Neither of us could find a 40A socket that was labelled "trailer" anywhere. Then we found the various trailer lighting fuses and thought maybe we were wrong. That the 40A was used for the 02s and the 03s split all the fuses out.

Well, I made the assumption everything was right and good to go. We have a camping trip planned for this weekend. I have already hooked up the camper once to make sure the brake controller would detect it and that all the trailer lights were working correctly. I never checked the hot lead with a meter. Boy would I have been scratching my head come this weekend!

Anyway, I just went down and checked my truck for this #1 stud and red plug. There it was! Called the dealership and they had one for $4.62. They called it a "maxi-fuse". I then called NAPA with this part number, and they had one in stock for $2.69.

Cha-ching! More money and time saved thanks to TDP! Just wanted to say thanks for the info! I will take some pics tonight to put on my website for future reference by folks. A pic is worth a thousand words.

[jbplock]

Dittos to thanks for the fuse info! I had been looking for some of these fuses to have as spares. I also didn't realize that the B+ terminal in the fuse box is for the trailer harness. (I used it to get power for my bleeder pump) :eek:

FWIW here is a picture of the B+ terminal (with the orange wire connected)...

http://community.webshots.com/photo/67970835/74167702MsWaTs

smile.gif

[DieselDixon]

Since the 12 power feed does not have an isolator I have installed a selonoid in the camper wire harness under the front (driver's side) corner of the truck bed. I spliced into the brown (running lts) wire to drive the selonid switch. So whenever my driving lights are on then I am charging the camper battery and when I'm parked the camper/truck batteries are isolated That's a great idea! I did not even think of this. So does this mean that whenever the trailer is plugged in currently (without solenoid) the trailer will be working off the truck batteries as well, even if the truck is not running?

Which wire did you tap into in order to control the solenoid? What type of solenoid did you go with, type and rating?

Thanks

[SparkyTX]

When the trailer is plugged in without a solenoid or isolator, the trailer battery is connected in series with the chassis batteries. Electricity will always follow the path of least resistance (like water), so it will fairly quickly equalize the charges of the three batteries. So if you have a low trailer battery, you will soon have three low batteries (although not as low as the trailer battery originally).

In the setup discussed above, the trailer battery would only be connected to the chassis batteries (and charging circuit/alternator) when the parking lights of the rig are on. If you are driving down the road without your parking lights on, you alternator is providing no benefit to your trailer.

A more all-round choice would be to mount a switch inside the cab. This is the same method I use for connecting my dual batteries in my 4x4 gasser off-road rig. The switch is wired to a high amperage continuous duty solenoid (found at any boat or rv supply shop for around $40). The switch is a 3 position switch (ON-OFF-ON). The hot for one ON position comes from the ignition circuit. With the switch in this position, all the battereis/charging circuit will be connected anytime the key is in the ON position (usually engine running). When the rig is off, the trailer and chassis batteries will be isolated. The second ON position would draw its power from a full-time 12V circuit. This would be an emergency position. I can't really think of a reason for this in this setup, but it could be handy. This would connect the batteries anytime the switch is in this position, regardless of the iginition circuit switch. In a off-road rig, this setting is used to connect the batteries with the ignition off, like when combining batteries for winching power when the engine is off.

This setup is more intense and would take more effort, but would be a better all-round solution.

Of course, you could just put a switch attached to a solenoid on the trailer that you use to manually connect or disconnect the batteries. But if I were going to do that, I would just unplug my trailer plug when I wanted isolation.

If you are interested in more details about the in-cab switch, holler. I have some diagrams I have distributed to my off-road buddies regarding my dual battery setup on my big Jimmy.

[akrockhound]

To DieselDixon:
I tapped into the brown wire which is the tail-light wire. They make slick "snap connectors" (can get at napa) that you place over the wire you want to splice into and also accomodate the end of the new wire you are adding.

The selenoid rating I can't tell you. I purchased at an RV supply. they are sold pretty much for this purpose but make sure it is "continuous duty" and at least 30 amps.

Here they recommend that you drive with your headlights on all the time for safety so this seemed like a logical wireto tap into.

On my last truck I had a switch mounted in the cab and even though it was right in front of me I usually to forgot to switch it off or on so i was either driving without charging my camper batteries or parked and draining my truck batteries. I am going to try this new setup for a while.

To answer your intiital question though-- YES-- unless you install an isolator (selenoid) then you trailer/camper can drain your truck batteries down.

Good luck

Gotta love this website!!!!!!!!!!!!!

[slapshot44]

I am using one of these isolators and am very satisfied with the performance...

http://www.hellroaring.com/rv.htm

[DieselDixon]

Well it sounds like something I am going to have to do. I think I like all your suggestions and this is how I am going to do it. A 3 position switch on-off-on, wire one side to the driving lights which are always on when the truck is in gear and then the other side direct to the batteries incase I ever get in the emergency situation as Sparky stated.

Thanks for your help guys.

[Doug Richter]

Ok this is just a dumb question but if you have two dead batteries in your camper and hook up to the truck and only have a 30 amp solenoid in line acting as an isolator how long will it last when your 180 amp dual alternators start charging the two dead batteries? How long will the 40 amp fuse on this circuit last? I would imagine if GM planned for a 40 amp draw on the circuit one should use at least a solenoid capable of 40 amp continous duty. Now if you dont install a isolator and leave everything hooked up when you plug your camper into 120 volt power and the charger is running in the camper IS it also charging your truck batteries too?
Doug

[SparkyTX]

I don't see why the camper's charging system wouldn't also charge the chassis batteries while plugged in to 120V power, btu I cannot speak for sure.

I agree on the solenoid rating. In my offroad truck where I have this setup, I run a 200A continuous duty solenoid. That easily handles my 180A alternators output as well as the huge draw of my offroad lights, winch, and other accessories.

I got mine at a local boat/rv supply shop for something like $40.