Sorry so long, but I'm needing a little help on what I think is a wiring problem. I read this forum quite a bit and know there is some great advice on here. Anyway..My truck is a 2002 Chevy 2500HD LT. About a week ago, I was hauling my horse in my '04 3H 4-Star and I had trouble getting the truck into the tow/haul mode out of my lane. I finally did (indicator light finally came on in my dash) and went on my way. Well, after I got to my friends place to pick her & her horse up, I couldn't get the tow/haul to come back on..this is after shutting the truck down and restarting it to go. Just by chance, I manually checked my trailer brakes, and they didn't seem to really kick in either. Well, thought we wouldn't go, but all of a sudden, by trying the tow/haul button several times (shifting the truck to D-3-2-1 ect.) it finally came on. I did check my trailer brakes again and they still didn't seem quite like they should. I was second guessing it...adjustment?  - Decided we should be O.K. with the tow/haul working.-- I will say that I did drive slower than I normally do--I'm pretty careful, anyway. Well, we got to our destination, no problems, then ready to leave--getting dark--wanted to use the interior horse compartment lights to load them up AND they wouldn't work! All of my running lights, brake lights, turning signals...worked. THEN I couldn't get the truck into tow/haul mode AGAIN!! --I bought the truck used going on a couple of years ago...LOVE THE TRUCK...(My old truck is a Ford..been a Ford fan forever...And I really considered a Dodge..even called on one..so...I really don't want to start something here.. I'm not prejudice..!!:)) I bought my trailer new and it really hasn't had a lot of use. SO...then, when we finally pulled into her drive, I noticed the camper door light was on. When we stopped, I tried the tow/haul button & it worked!!  Good!! I left the truck running while we unloaded her horse so I would be sure to have tow/haul for my trip home. Oh, and the camper door light went off on it's own & when I checked, the switch was "on" in the living area. Must have switched it on trying to get the interior lights to go on. I will say that I am using an adaptor, my trailer is a 6-hole (because that's what my Ford has) and my Chevy truck is a 7-hole. The thing is, if I'm having trouble with the tow/haul coming on, wouldn't the problem be in the truck wiring? Yes, I've considered fuses, but I would think the lights wouldn't come on & off like that. They would just be OUT completely. Right? Loose fuse? Is there such a thing? ALSO, I have used this set-up before without a problem. Even went to Eminence, Mo. (lot's of hills) last spring and couldn't have been happier. Why now? Could it be the adaptor itself? Because this is a different adaptor, brand new, but different. I let the old one go with my other trailer we sold. Needless to say, I'm not wanting to go anywhere until I get this fixed...but what is going on? MAYBE there's two completely different things going on. I suppose that's possible.-- I did use this truck a couple of weeks ago to pull my little 12'steel bumper-pull to take our 4-wheeler for a tune-up. The tow/haul worked then. Don't have interior lights & it was day-time. Didn't notice anything about the brakes--light load--didn't think to check manually. BUT, I didn't use that adaptor for that trailer... That wouldn't have anything to do with the tow/haul though, would it?  I've also read about maybe the ground? Would that be possible? To mess up so much? AND, how do I check for this? --Again, sorry so long, just want you guys to know all the details. --Any help would be greatly appreciated.--Thanks

Ditto on what TRESVOLTE stated; get rid of the adapter and purchase a plug to match your truck. It's less than $10 and a few minutes well spent.

Gard

Well, shoot. Just came in from trying the truck out. Started it up, not hooked up to the trailer, and tried and tried to get the tow/haul mode to come on. It finally did after shifting through the gears a few times (D-1-2-3) (don't know why I think that should work, but it did by chance) Then, I couldn't get the mode to shut off!! I shut the truck down, started it back up, then couldn't get the tow/haul to come on at all. SO... I guess I need to take it to a garage to have it checked out. It just seems funky that all this came on at once, with the trailer breaks/lights acting up also. It seems to me that there are two different things going on. Oh well, thanks again for your help and I'll keep you posted.

You may need a new NSBU switch on the Allison 1000 transmission.... 

http://www.thedieselpageforums.com/tdpforum/archive/index.php/t-19578.html

Or it may just be a bad tow haul switch. Take it to your dealer and have them check it over.

Sounds to me like there's an electrical problem in the switch on the shifter stalk.

When you're shifting the transmission, you're wiggling the switch connections.  Try just tapping or moving the shifter handle and the steering column and pushing the tow/haul button.  (Without actually shifting the transmission) If that makes a difference, you can isolate the problem to the steering column.

As long as your adapter is right, they will. Some 6 way plugs were wired with center brakes and some with brakes on upper left. I haven't looked at an adapter in a long time, but they used to sell one at Wal Mart that you could open and change only the right two wires to fix the problem. On most trailers it was the hot and brake switched, so if your hot worked on your truck and your wires were switched, it would lock down your brakes.

You know what, Tresvolte? I agree with you. It HAS to be two totally different things going on here. I know what I can do tomorrow. I can hook my old Ford up to the 4-Star and see what happens. They both have the same 6-way plug. That's why I had my 4-Star switched over to the 6-way plug to begin with. I pulled it with THAT truck. DA!! :) And I KNOW everything with the brakes and lights worked then.---And another thought crossed my mind...maybe it's the plug that is mounted on the back of my Chevy truck. It's mounted back by the Reese hitch, not inside the box (yes, I want to have that changed also) You see, even though it's an '02 model, they never had a gooseneck ball installed. I had a B&W hitch put on... SO... I suppose that is possible. --NOW, as far as the tow/haul mode. I'm thinking that hosspuller might be on to something. It could be in the shifter stalk/switch. I did a little research on the "diesel page" (thanks retento) and found that a couple of other people had the same problem. One replaced the whole stalk and one took it apart & soldered the connection. WELL, this all sounds good, anyway. Thanks again, so much, for the responses. You guys are great. I'll keep you posted. --Oh, and I still plan on getting it set up right so I can ditch that adapter!!  :)