Pulling problem

[Obsessed racer]

I have been having a problem when pulling my car trailer (about 8000lbs). It only seams to do this when I am going 75mph. Flat ground or up hill dosen't matter. It will go into limp mode with no codes at all. It will reset itself in about 10 seconds all by it self. It has happen 15 or 20 times and I have know idea what to do next. I have had it at the dealer 3 times for this problem and they have no clue. I have a banks Exhaust kit and an air filter but no chip. The dealer has re flashed the ECM and the tranny.

Any thoughts?

Thanks Don

[Tough Guy]

Check all electrical harness connections and grounds pertaining to the drivetrain...

Might want to throw a wrench on the battery posts as well.

Cheers,

The "Boy" TG ;)

[Obsessed racer]

The dealer did all of that they changed filters and everything.

[madmatt]

give me some more info on the truck and I'll see what I can come up with.

[Obsessed racer]

2001 3500 4X4 dually 70,000 stock except the exhaust and air horn from Banks. I got the truck used last year. It runs great except for this problem I wish I could figure this out though. Before 100,000 so they can fix it.

I have been told that if the tranny slips it will cause this problem but I can't get anyone at the dealer to except this. I am going to call GM real soon but I need to get more info so I can get them to understand.

Any help would be great.
Thanks, Don

[madmatt]

what indications or symtoms does your truck show when it goes into limp mode?

[Obsessed racer]

It just has no trottle you can push it down and it does nothing. In about ten second it just comes back

[More Power]

Not a lot to go on without codes......

A contaminated MAF sensor (K&N air filter). Clean with a spray oil-free carb cleaner.

Excessive vacuum in the fuel tank due to a defective fuel cap vent (try running with a loosened cap).

MP

[Splash n Dash]

Not saying that it is an injector problem, but that is how mine started exactly to the "T", limp mode, no code, then diesel and oil all over the underside of truck and front of trailer. Went into limp mode only when I was pulling a trailer but not when I was empty, can't remeber the time frame, until it had the major problem. I also know of one other truck that this happened to also limp mode, no code, dealer didn't know what it was, pulling trailer only and then it happened. Both trucks were 2001 Chevy c/c 4x4 w/Ali. around 65,000 miles trailer weights were both 10,000 to 12,000lbs. Again not saying it is the problem with yours, but sounds like the same thing.

[madmatt]

I'll ask again,, How did you know it was in limp mode? Before your truck goes into limp mode something must be showing up in your ECM out of spec. If it's not setting a code thats odd but w/ a VDR you should be able to get a snapshot of the failure and compare it to the data from a like vehicle under the same operating conditions. Mechanical failures could cause it to go into limp mode, but only after your ECM sees out of spec data from it's inputs.

[Obsessed racer]

Madmatt I guess I am assuming it is limp mode because that is what the dealer told me it sounded like. I am as confused on this problem as well. It should be giving some kind of code but it isn't. I am just looking for some logicical solution because I feel the dealer is just trying to get it out of warranty so I have to pay for it.

Thanks Don

[madmatt]

on the allison, limp mode only allows N, R, or third gear operation and is usually defaulted to w/ internal hydraulic failures such as clutch failure, solenoid failure and stuck valves. W/ yours I'd lean towards a stuck valve.

[CntrlCalDmax]

Use to happen to my '01. Never did find the cause. Hoot had the same thing when he had the Dmax. I don't think he ever figured it out either. It's not a limp and it won't set a code. Only happens when towing and seem like if you hold the throttle around 30% it comes back the soonest.

[jfish]

My 2003 did this same thing a few times only with a trailer on flat ground no inclines. After switching the truck off for 15 minutes or so everything came back. After driving around for few days the check engine lights go off and all codes cleared. I did have a code at first P0700 I think. Just stating that the tranny limped or so I gathered.

When my tranny limped I only had N and 3rd no reverse as stated in previous post.

From reading alot about limping tranny's once they do it they do it alot easier from then on.

[ed s]

Mine did the same, injector failure!

[jcummins]

For what it's worth - Mine did a similiar thing when I was using an aux tank to feed the engine. I converted the tank to a transfer tank, so I run only off the factory tank now. Has not repeated that problem since. I conclude the problem was a fuel pickup...got air in the line, when I was using the aux tank.

[Heartbeat Hauler]

I wonder if the guy before you did any mods and fried the clutches in your tranny and it only shows up under strain. I thought that the slipping that sets codes was when the torque converter slipped more than it's suppose to. Just thinkin' out loud.
JP