Transmission Problems??

[mquade6988]

Help! I have a 2001 DMAX with 13k miles. Truck had been sitting about two weeks. Went to move it, put it in drive and transmission shifted with a bang! It acted like it was taking off in high gear. It went forward reluctantly like it was in 3rd gear. Tried to back it up but it would not move. Check engine light came on. Shut it down. 15 minutes later tried it again. It drove normal including reverse. Engine light is staying on. Last year, on a few other ocassions, it down shifted with a loud bang but since it was an isolated incidence, was not too concerned about it. Back during the summer, the check engine light came on. Took it to the dealership who replaced a boost sensor. Since then, it has come on periodically when towing a gooseneck trailer. I am very worried now. I am getting ready to take a 400-mile trip, leaving next Wednesday towing a horse trailer. Don't want to be stuck away from home with a horse on the trailer.

[FirstDiesel]

I think if yopu do a search on tranny problems here you will find that this is a "normal" issue. Letting the truck sit for 2 weeks allowed the tranny to drain down the fluid. The way to handle this is to start the truck and idle it a few minutes without putting it in gear. Then shut it off and restart it before you put it in gear.

[mdrag]

mquade6988,

FirstDiesel's giving you the correct advice.

Some time ago, BigAl posted the explanation on why this happens. Basically, on some trucks the torque convertor will drain down after setting a spell. When you start the truck, air enters the transmission until the convertor refills. The sensors are expecting fluid pressure and don't see it, setting DTCs and the SES light.

If you start up the engine and DO NOT shift into gear, let it run for a minute or two, then shut down. Restart and then move the gear selector and you should be OK. This way, all the air should be out of the system before selecting a gear.

SteveO commented on this issue a few weeks ago. Apparently there is a newer part that will fix the problem. I'll see if I can find the link. Good luck.

[mdrag]

Here's the link to a recent topic with much useful info from SteveO :

http://forum.thedieselpage.com/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=7&t=004558&p=

mdrag

[SteveO]

mquade6988,

The first problem you talk about sounds exactly like the Converter is draining back just as these guys have told you..

The other part does not.. The hard downshift sounds like the 2-1 downshift bang.. Have the TCM updated to the latest software level...

The last part your talking about the light coming on periodicaly while towing.. That sounds like the ECM needs to be updated (reflashed) to the latest software level...

Thanks guys for helping out.. I haved been busy,,, as usual..... smile.gif

[mquade6988]

I think I might be getting a "snow job." I took my d/a to the dealership today. They replaced the neutral safety switch and reflashed TCM with updated program for transmission. I told them what you folks had advised. They said they had to go by what GM tells them not what I hear from a chat room. Needless to say I was not too happy. So when I got home, I called the 800 GM service number. I repeated my story to the gentleman who answered and asked if GM had heard of any of these problems and how did they resolve it. I also asked him what the purpose of the neutral safety switch was. He said "No" and advised me to talk to the dealership. My gut feeling is they didn't know how to fix it and just put something on it thinking that would satisfy me. Now what???

[mquade6988]

Did I understand someone to say there is an allison bulletin on this? If so, my dealership was not aware of one. Can you tell me the bulletin number? Thanks

[FirstDiesel]

I'm not sure I understand what you are looking to have fixed. They reflashed the ECM and TCM for you. The switch has nothing to do with the problem but you got a new one, hopefully the new style. Is it tan or black. As for the drain back of the converter, Steve said there are springs that will fix the problem but I do not think GM is authorizing this repair. If I understood him the tranny needs to come apart and that's not happening at the dealer level yet. The cure is what MDrag and I said. Start it and idle, shut it off and restart it. The converter is filled and there is no code or problem.

[tjdonald]

I too experience last night while snowplowing a massive "bang" while shifting from R to D. I actualy though someone smashed into me. After this loud bang, the gear indicator on the dash was "sluggish" to display the gear when I continued to shift from R to D etc. I also now notice a clunking when in 4WD and reversing, almost like a loose U joint or something.. From what you are posting this is a software correctible situation?

[mdrag]

tjdonald,

Sounds as if you may have a NSBU switch malfunction.

Check this link for more info:

http://forum.thedieselpage.com/ubb/ultimatebb.php?ubb=get_topic&f=7&t=004742

There are pics of the NSBU switch (old and new design) at the links in my sig, with the part# for the new tan switch on the box clearly visible. Check the 2nd or 3rd link in my sig, then choose the Allison NSBU album. Good luck.

mdrag

[ 03-05-2003: Message edited by: mdrag ]</p>

[Redhawk]

After a month away I hopped into the truck and started her up. I put it into drive and it just sat there. I remembered the post about this, so I restarted, let it run a couple of minutes and away we went. I've let it sit for a week or so before and this problem never happened.

Is this a problem that will get worse over time? If so that would worry me.

The other problem where the transmission went into gear with a bang sounds like something that a reflash update will fix. I had a downshift banging-into-gear problem and a reflash fixed that one.

What bothers me most about mquade6988's problems is the dealer's attitude towards them. He should be just as concerned about fixing something as his customer is. When I had my reflash done the service manager was glad that I had info to give him that I got from the DieselPage. He was interested in fixing the problem, not avoiding it.

[mquade6988]

FirstDiesel: As you said, the switch has nothing to do with the problem. So...did the dealer fix anything? The cure of starting, idleing and shutting it off was, I thought, a temporary fix. I checked the link that mdrag referred to. It talked about weak springs and replacing them. My concern was that if these springs are not replaced, the problem would get worse in time (after warranty runs out).
tjdonald: Well, at least I know now that I'm not completely crazy. Last summer as I was pulling off from a traffic light, it shifted so hard that I thought the truck behind me had smashed into me. I actually pulled off the road and looked at my rear bumper. Since I saw nothing, I thought my transmission had gone bad. After thinking about the expense, my next thought was the embarrassment of having my "Ford" neighbors find out about it. But, I pulled back onto the road and it drove like a dream.
I'm not looking to have a problem. I just want reassurance that there won't be a problem down the road after the warranty runs out. I don't have any confidence in the two dealerships we have in our area. I feel they are lacking in d/a knowledge.

[BobNelson]

Gee.... guess what happened this am.... Started the truck after 3 weeks of sitting. Fortunately, I had been reading this post... Started, run 10 min, let sit, shut down and restart... Really didn't want to go. SES light on. Started again.. SES light but it wanted to move.

Drove 20 miles to town/work and directly to dealer. Super dealer.. Had it back in 4 hours.. Cleared the SES and a switch on order. Should be here in a few days. Dealer said if the SES light comes back on, bring back and they will give me a loaner (Caddie). Love my dealer. They even changed my fuel filter for $25... (I supplied the filter).

[mquade6988]

How about sending that dealer to Maryland!!! They don't raise them like that around here anymore. We had to go to Ohio to buy our truck in May 2001. They were too greedy around here.

[tjdonald]

Interesting comments on the xmission problem. All this started after being hung up on a snow bank while plowing .. sort of fits the senerio you guys are taking about with the water in the switch /sensor. The truck has been running fine since the event.
My concern is when the warranty runs out .. Thanks for your feedback...

[FirstDiesel]

1 more time

The switch didn't fix it. The dealer didn't fix anything. Yes there are newer springs. No GM is not installing them in the field, according to Steve O who does this for a living.

The idea is it's not really broken. Just start the truck and idle 1 minute and turn it off BEFORE you try to put it in gear. As to worrying the springs are going to get weaker?? I'd worry more about things that are likely to happen.

Want to lose sleep over this and get all worked up trying to get it resolved?? Not me, I'd run the truck and turn it off. Better yet, I'd drive it more often. smile.gif