P0740 || TCC Out of Range
 

Howdy! I'm new here, I ran across this site while looking up information on an Error code I was having. As the title says, it's P0740 TCC Out of Range. I'll give you some history as to how this light came to be, and you can smack me with the idgit sticker for whatever it is.

I was traveling to another city to pickup a 2 slant Horse Trailer. I've hauled trailers before, so I'm not a complete idiot with them. Though, these other trucks I drove were much older (1979 Ford F-150 w/ 400 in it, and a 1996 Ford F-150 w/ a ~300 Inline-6). Though, the 79 is an Automatic Tranmission, and the 96 is a manual. Anyways, I hooked the trailer up, and came home over the mountain pass. I noticed a huge spike in my gas consumption, I had dropped from ~13mpg, to ~7 - 8mpg. Which shocked me. I pulled over at a gas station, and gassed up. Put the truck in gear, and left. About 45 minutes from home I see an orange light pop up. I went to AutoZone and borrowed their ODB2 reader, and the code was a P0740, they had no clue what that was, or how to fix it. After doing some research, and talking to a few mechanic buddies, they all told me it'd be safe for me to do my return trip with a horse + trailer. I did nothing happened.

I started to think about it some more, and realized that I was asking a LOT out of my Transmission for pulling a Horse trailer up a mountain, while there were nasty gusts of wind. I hadn't really noticed the wind because I was behind a semi for most of the trip, until I went to pass him. Be easy, I'm used to older trucks, and I was told I didn't need tow mode when pulling an empty trailer. Boy was he wrong.

Would you agree that the high gusts of wind put too much strain on my transmission?

20009 Dodge Ram 1500 4X4 SLT.

What engine? What trans? How much did the trailer weigh? How much with the horse in it?? Any modifications to your truck? Larger tires, that kind of thing?

Engine: 5.7L Hemi
Transmission: Unknown (Put VIN in oreillyauto.com and got these results)
Trailer Weight: 2780 (With horse, roughly 1000lbs)
Modifications: None. Completely stock.

If I remember right, the 1500 has a max hauling capacity of ~9,000lbs, I'm pretty careful when it comes to my possessions. I treat things right, they last longer that way. I've been told that this trucks engine is essentially a sports car engine, thus it's always being hotrodded around. I can see that by the way things have been going for me. The truck was purchased with 98,570 miles on it, it was originally sold in Alaska. After reading some information on this site, I plan to use Tow/Haul Mode whenever I've got more than 500lbs in the back of my truck. The check engine light turned off, however, I'm going to take it into the shop tomorrow anyways. Rather be safe than sorry!

I don't think that weight should have such a profound affect on fuel mileage..... suppose it depends on the terrain. In the mountains, yeah, I suppose..... With that much load on the truck though, I would wager that the MDS system (provided yours even has it, not sure...) is likely disabled..... that will have an effect........

Actually, I think you're right. I don't think I have MDS, or it's disabled. I test drove a truck with MDS, and you could notice it, a lot.

Would it be worth it to look into enabling the MDS? Took my truck to the shop, but they couldn't do anything because the "Check Engine Light" needs to be on before Extended Warranty will cover it. How annoying.

I don't think you really want MDS active while towing........ power drops off like a stone when you disable several cylinders, and with a trailer on it..... it wouldn't stay in mds mod long anyway. (in fact, I would suspect that it would never enter mds mode, given engine load values, and such.)

Well, I still do a lot of driving, it'd be nice to have a few cylinders shut down when I'm not using them. I have a 45 minute commute to work, and I visit my family which is 2 - 3 hours away. If I could turn it on when I'm not hauling a trailer / heavy load, that would be awesome.

Guess I'll have to look into it more.