pquevill

This is the 3rd year in a row and naturally, it never happens when you take it to a mechanic, but anyway, my 2000 Dodge 4WD with AT start gear finding or hopping between overdrive and 3rd gear. It will only happen at 47 mph and it shifts back and forth from 3rd to OD and almost like it is cutting out on fuel or something. If I am at say 40mph and steady increase speed it will shift normally to OD. Just when you're in the 45-47mph range cruising that it shifts back and forth. Sometime it does it between 2nd and 3rd as well.

One Dodge dealership replaced the speed sensor and that seemed to solve it, but then came back again. And the strange thing it only does it for a week or 2 and then dissappears for another year. It only does it in the summer, however. Most dealerships don't have a clue yet?

Any ideas? Thanks for any info!
Q

Puke

Reset your APPS when this happens. It is very easy, and 90 percent of the time your problem will be taken care of.
The instructions to reset your apps are on this site somewhere, and very easy to follow. Basically, you reset your computer (from scratch), where the shift points are.

I believe the shift point should be under 47 mph,(unless your foot is slightly in it). Every time I reset mine, it shifts at about 42 to 43 mph into overdrive, ...this is without having my foot in it at all.

The first times this happenned, I took it to the dealer and they re-flashed the ecu, etc., and it came back ok. But it's a helluva lot easier to deal with it yourself.

luf02145

My '99 3/4 ton has been doing the same thing. Except mine does it consistently, not just for a couple of weeks and then stops. One thing that I have found to help "sometimes", is removing the output shaft sensor on top of the transmission and re-seating it. It's on the rear portion of the transmission on the drivers side, kind of up on the top, has two wires going to it. This doesn't work everytime, but most of the time it does solve the problem for a few months. It doesn't seem like the sensor is bad, but the wiring connection might be loosing good contact.

I have a feeling that my transmission is on it's way out. Lately, especially when pulling a load, I'm getting some vibration when shifting into high gear. It's only for a moment, but definitely there. Does anybody out there have any recommendations for a replacement transmission for a '99 3/4 ton 24 valve, automatic. Where you would buy one, and how much trouble is it to replace. I'm a decent mechanic, and have more time than money. I have rebuilt many tractors and do a lot of work on farm equipment, but have never replaced a transmission in a truck before.

RowJ

With 3.55 rear end, I don't get near OD unless I'm over 55-60 mph. I lock it out so it can't search for a gear or lug the motor.
Shifting from 3rd to OD at less that 55 mph put you well below 1500 rpm and into a very tall gear........with a computer trying to decide what gear is called for!
I find I can better decide that...based on what ahead on the road.

RJ

1-2-3

luf02145, You can do what I'm having done right now. Get it rebuilt. It's gonna hurt either way you go. A brand new one is awfully expensive. Not sure how much but it's alot. I wouldn't consider a used one from salvage, because you never know of it has one day or a year left. So a rebuild is about the only answer. Depending on what it needs it'll be $1400 -$1800, plus they will give me a year warranty.

It stinks, but I'm trying to keep in mind I only paid about $10k for my whole truck 3 years ago when it had only 59k miles on it, so even with this, I'm still gonna be ahead on it.

y2kram

Reset Instructions Here

Silverjay

My tranny was doing the same thing and the dealer I bought it from threw and APPS, position sensor, and speed sensor at all of which did not fix it. I put on a Happi box and it also did nothing. I called DTT and they recommended a throrough cleaning of both end for all of the battery cables. This includes the negative cables and the ground cables that go to engine block. This completely fixed my problem. DTT recommended a noise filter (around $35) if the cable cleaning did not fix the problem. I think I talked with Stefan about it at the time.

pquevill

Thanks for all of the information. I'll give it a shot in the next day or 2 and report back. Appreciate it!
Q

Ranman

Still think you ought to wrap the green striped ground wire that goes by the alt in alumium foil and clean where it grounds to the finder well behind the air filter. Really worked for me. really easy to do.

pquevill

Success!!
I finally got back home to try the APPS refresh and thanks for all of your help. It was very simple, but never did find the green striped ground wire. Anyway, the truck runs great and no shifting anymore, it actually seems that it is shifting smoother as well.
Again, thanks!
Q

Extra300

Sounds crazy, I know, but check the batteries. Voltage drops can cause the electric torque converter, controlled by voltages read by the computer, to shift in and out of lock-up. This will usually happen between 35 and 50, except when accelerating. I didn't solve this problem till I replaced all the original battery ends. The corrosion was inside the insulation where one couldn't see it. This resistance was the sorce of my problem. Start there, and also clean all the grounds, and check your batteries for strength. If it persists, and I'm guessing it won't, DDT makes a noise filter for the signal wire to the computer which controls lock-up, amd, a jumper can be installed from the throttle position sensor on the pump, to the computer.