I've posted this in the transmission forum and received no answers. Hoping maybe someone here can help. Last weekend I pulled our new Toy Hauler with my 2006 3500 GMC with Duramax and 4L85E trans with full factory towing package. Three times, while slowing/braking, the trans seemed to shift in to neutral and the truck wouldn't move. It's done this at start up since I've had it (6 mos) when it's cold. Let it warm up and it's fine. This past weekend it was warm. After about 20 seconds,it will wind down and then drive normally. This increased the pucker factor on our first RV trip signficantly. Anyone have any ideas on where to start? No codes are showing, no CES light, no flashing tow/haul button. I was pulling in 3 with tow/haul on. The van has 57,000 miles and the tranny was serviced at 52,000. Was doing it before servicing when cold so I assumed it was normal (wrong again). This is the first time it's done it while being driven. Gotta get this fixed before we get run over. Any help would be appreciated.
Ed

Is it out of warranty? I have not read about many trans issues with the vans but you have one for sure. How was the old fluid, burnt?

Three times, while slowing/braking, the trans seemed to shift in to neutral and the truck wouldn't move. trying to figure out what exactly you mean here? you braked to slow down, but the truck wouldnt move after braking?

Fluid looked and smelled excellent. Yes, the truck wouldn't move after braking. Of course, the other times it was just slowing down coming off an interstate ramp and not completely stopping but still easing the brake as needed. The other scenario is it doing it first thing when cold. Fine after a few minutes of warm up. Didn't do it at all this morning though. Just cranked and drove off. Wanted to check if it would move in reverse but of course it acted fine. Thanks for replies guys. I'm scared to put it on the road.
Ed

Forgot to answer but it's out of warranty.
Ed

so when it acts up, you push the gas while in drive, and no go? does it eventually bang into gear and go if you hold the gas down?

Nope. I have to let off and wait and then everything idles back down and tranny slips smoothly in to gear and it pulls fine. No banging at all. It's really weird cause when it does it there's a lot of noise from the engine winding up and the turbo and then it gets quiet and I know it'll go.
Ed

that definetly sounds weird.

kind of sounds like what mine was doing in reverse. But mine was only in reverse. They replaced reverse band and piston in it.

I gave up and took it to a recommended dealer and he's had it for two days and can't find anything wrong. I should'a known. Still haven't got it back and don't know what to do when I get it back. I can't use it for fear of being stuck out in the sticks with no cell service or getting killed when an 18 wheeler runs over us. I'm going to be forced to trade the SOB in. I think I'm finished with any GM product. I'm convinced they can't make a transmission that's worth a crap.

Ed

got a lemon law case filed on mine for tranny issues. while the generals letter was in the mail to my attorney saying my van is fine, I had it in the gm dealership. gm mechanics said tranny needs to come out. hmmmm. good luck with yours. i'd try a good non-gm transmission shop. maybe there is an aftermarket better made tranny available.

That roaring sound you hear is the fan coming on. It feels like the transmnission not engaging but if you listen carefully, that is the fan.

It loads up the engine and makes a lot of noise when it comes one so one would feel like the engine is not going.

This happened to me and It scared me until I realized that it was the fan, not the transmission.

Jojo, it wasn't just the noise. The van will just barely move, maybe even just rolling from being down hill. No matter how much I mash the pedal it won't go. Believe me, when that 18 wheeler was on our butt blowing his horn with the wheels locked up, I was mashing with all I had. Also, why is the fan so wound up when the engine is cold first thing in the morning?

Ed

When you had the throttle mashed, were you blowing smoke ? As for the fan wound up on cold mornings are you just refering to high idle ? Maybe you should invest in a Edge Insight like I did. That way you can see what the computer sees with shifts and etc.

No excess smoke. Other than trying to get us killed, this thing runs excellent. It shows no codes. What exactly is an Edge Insight and what's it do? I'm damn tired of spending money on vehicle repairs. I just want one that will do what's it's designed to do. I've always taken excellent care of all my vehicles and am pissed that I've been bit by the transmission bug again. I'm going to buy a Ford F250 with the new 6.4 powerstroke and the longest bumper to bumper extended warranty I can get my hands on. GM will never see another penny of my money even if I have to ride a horse!! Sorry for the language but I'm fed up.

Ed

Edge Insight plugs into the diagnostic port and functions as a gauge and can read and clear codes. It displays everything a scanner does. The Edge Products website will tell you everything. If you look at my garage you will see how I mounted mine. Thats sucks you have problems. Our vans have been great and we work them. Good Luck.

I can't believe the dealer can't fix a 4l85 issue which is the same basic trans used since 91 in everything over 8500gvw. It is also one of the most reliable they made. I would find a private trans shop and see what they say.
Good luck with the Ford, they are a nice truck but they have plenty of issues which are way to common. All the warrantee does is keep the dealer fixing it, your still out the truck when it's in the shop just like you are now.

Joey, one thing in favor of the Ford is my son in law has been a service writer for Ford for 11 years. He's willing to share all the problems with Ford and help me get a good vehicle. He's a sharp kid.

Ed

That will help. I like the new Fords so good luck with it.

I agree w/ JoJoJaro , it probably is your clutch fan . When it happens take it out of tow/haul and put in drive , tow/haul seems to make it worse , higher rpms , increased fan speed and more drag . It has the biggest power robbing fan I have ever had . The clutch fan locks in in the morning occasionally , search Third Generation for the clutch fan . The p/u's only have the cold locking fan issue . I will bet your trans is fine . I can't give you a better solution than getting out of tow/haul , city traffic in high heat brings it on for me or after running in the heat getting off a ramp , just like you have described.It takes a little bit for the cooling system to catch up for some reason ,it doesn't overheat , but sucks the daylights out of the power. I was looking into getting an electric fan to help stop it . This is the only issue I have with my van , the clutch fan that makes you think your trans is bad .:(

I am starting to agree with Big Windy on this one. I would check out your clutch fan. Also the next time you tow put it in 4 gear with tow/haul. What are your engine temps during this ?

OK guys, I'm here to see if anyone knows how to get this "Dumb Ass" off my forehead. I went to a different dealer who convinced me to hook up my 28 foot toy hauler and pull it 20 miles to them. Their transmission specialist who looked to be 12 got in, hooked up his computer and said let's go. We drove in every kind of scenario you can imagine for about 2 and half hours. When I got it to do the "slipping" with all the fan noise he said to mash the crap out of it. I did and it worked fine. Instead of letting off when the noise starts just give it the gas. It worked every time. The noise it makes made me feel that a rod was coming out or the head was coming off. It wasn't even pulling 1200 rpm. Wish these vans came with a tach. We followed everything on the computer and he said it was running as good as any new one he'd seen. It's strictly cooling off when that big mother starts roaring and quits when it gets air moving and lowers the temps. I sure am glad I didn't buy that Ford, lol. On top of that, they didn't even charge me for running the diagnostics. Good dealership. Thanks for all replies here guys.
Ed

Now buy the Edge Insight so you can see RPM and such. Good to hear it was nothing to do with the van. From personal experience the "Dumb Ass" will eventually fade unless the wife and friends have a good memory.

Glad you found out what it was , probably a big relief . I was thinking of putting those Trans Am gill thingys on the fenders like the Ford trucks and the Escalade. Or maybe V2 can set something up , the truck doesn't overheat , but that fan is one wicked sucker. Hell I thought the trans was bad the first time it happened too. I had a clutch fan lock up on a 75 Buick on my way back from Florida , took it off , drove 1,100 miles home without a problem till I got into Chicago traffic.

A big relief is putting it lightly. I was ready to trade for anything else just to be rid of more tranny problems. The 1996 2500 light 3/4 ton Chevy I had ate two transmissions by 156,000 miles with NO heavy pulling. In fact, I got this van when it ate the last one and I wouldn't sink anymore money in it. The crankshaft had so much end to end play it was eating the tranny. Never had any indication of the problem. No oil usage or knocking. Rear seal leaked a little but was about normal for a Chevy. So finding this engine and tranny ok probably saved my marriage, lol.

Ed

glad its not the same problem mine is having.

Good luck, Lotsofmiles. Big Windy, I wonder how hard it would be to install an electric fan? That seems like a good idea. It could even be temp controlled. Like you said, it never runs hot just brings that big honking fan on and scares the crap out of ya.

Ed

Here is a tip for you. Open your hood and remove the rubber flapper that seals between the radiator support and hood. It will help with temps a little bit and also get more air to the filter.