Won't Shift Out of First

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akaproph:
A friend of mine has a Durango, the tranny wont shift out of 1st. I checked the codes with my Superchips (gotta love it), it had the P0720 code (Output Speed Senor *Malfunction*) on it, so I cleared the code. The truck still isn't shifting. I didn't check the relays (didn't think about it till just now) but the check engine light was on and I do believe that was it that I noticed.

Vehicle: 1999 Dodge Durango 5.9 Auto 2wd

Need some help on this one from owners/techs that have experience this first hand, no hearsay please.

cbonito:
Quote from: akaproph

A friend of mine has a Durango, the tranny wont shift out of 1st. I checked the codes with my Superchips (gotta love it), it had the P0720 code (Output Speed Senor *Malfunction*) on it, so I cleared the code. The truck still isn't shifting. I didn't check the relays (didn't think about it till just now) but the check engine light was on and I do believe that was it that I noticed.

Vehicle: 1999 Dodge Durango 5.9 Auto 2wd

Need some help on this one from owners/techs that have experience this first hand, no hearsay please.


Alright,

P0720 is triggered under 2 conditions, and I'll quote the "bible"....

1 The relationship between the Output Shaft Speed Sensor, and vehicle speed is not within acceptable limits.

2 Output shaft is less than 60 rpm with vehicle speed above 15 mph.

Could be that the sensor is screwy or could possibly be another problem with the trans.

Has your friend  ever changed the trans fluid, and what was on the magnet when/if he did?

The reason i say this is that I had the stuck in first problem and when i pulled the pan the front band anchor was in it and the front band was gonzo'd.

It might not be the problem, but that band is what puts you in second.

"Max" is a mod here with good experience, pm him and he will able to help more than I can.

Hope the code description helped. and that the solution is cheap :tu:

:
Cbonito, what you said is what I'd do first. There's either an electronic failure or a mechanical one. If its a mechanical one, the electronics are probably confused, which sets the code.

Tip: If its a speed sensor problem, you may find that the speedo isn't working very well. It'll not work at all, jump up to a certain MPH after you've been rolling for some distance, or it'll be erratic.

To check and see if 2nd gear is messed up mechanically, manually hold it in low 1, accelerate briskly to a speed that would allow 3rd gear and shift directly to drive. The trans should go into drive, if all else is operating ok. Or you could pull the pan and see if the front band strut or anchor is in the pan.

Have you checked to see if the code has returned after being cleared?

akaproph:
Quote from: Max

Cbonito, what you said is what I'd do first. There's either an electronic failure or a mechanical one. If its a mechanical one, the electronics are probably confused, which sets the code.

Tip: If its a speed sensor problem, you may find that the speedo isn't working very well. It'll not work at all, jump up to a certain MPH after you've been rolling for some distance, or it'll be erratic.

To check and see if 2nd gear is messed up mechanically, manually hold it in low 1, accelerate briskly to a speed that would allow 3rd gear and shift directly to drive. The trans should go into drive, if all else is operating ok. Or you could pull the pan and see if the front band strut or anchor is in the pan.

Have you checked to see if the code has returned after being cleared?


Well today I checked the for a code and it had nothing.  Then I put in the new output speed sensor (if it is a sensor w/ a one inch nut on one end of it) located on the driver side of the tranny about three inches from the crossmember to no avail.  Still wasn't shifting into 2nd, so I tried the pretty much what you said.  I put it in 1 low and gained some speed then shifted to 2nd and then 1st to 3rd, with no avail.  This trans will not come out of first.  I think hes changed the trans fluid a couple months ago.  Seeing all the threads about auto trannies makes me happy that I dont own a vehicle with one.   By the way the speedo is seems to be working just fine.  I'll talk to him about dropping the pan on the trans.  What are you supposed to check the tranny fluid in (neutral/ park).  Thanks for the help guys.

cbonito:
Vehicle should be running for a few minutes and in neutral.

Cycle it through the gears real quick and put it in neutral with the e-brake on, then check the level.

Yeah, sounds like it may be the front band.

You have a few possibilities....

One could be simply that the band strut bent and allowed everything to go slack thus dropping either the band strut or anchor into the pan. If it just happened and the band looks ok, you can put it back together and it'll be fine.

Two could be that the band is simply stripped of friction material. It is unable to hold the front drum to complete the 1-2 shift. This was my problem...

When the trans pan comes off you will know right away by looking at the magnet in the pan. It will be covered in metal shavings and gunk. When you check the trans fluid level with a clean napkin or something, you will see the contamination in the fluid when you wipe it off the dipstick.

Either case, the valve body needs to be removed to pull the band open and see if you have metal to metal, or if the band is good.

If the band is bad, and the trans contaminated, I would not attempt to just replace the band, as the rest of the thing is probably shot too.

The 5.9 and 46re is usually a dead giveaway that the trans needs to be rebuilt. We have had a few guys on here that were not too happy after looking into this.

This is why it's very important to follow the recommended service intervals on the transmission. Not only fluid changes, but also band adjustments.

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