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1997 3.3L Ply Voy: strange mix of Tranny / Tranny Display problems

5K views 15 replies 4 participants last post by  GlenBreeze 
#1 ·
1997 Plymouth Voyager 3.3L 188k miles

Transmission trouble:
In P and N, "all" the gears are indicated on the display, as if at test pattern.
R, OD, 3 display normal and function normal (except extra slipping at shift).
Tranny will not be forced into Low, and display will not show "L" (shows "L" then jumps back to "3").
P Code has shown P0700 and P1784 (and misfiring, which new plugs fixed).
Other than slipping (2nd to 3rd I think) and refusing to go into Low, driving is fine.

Have always used ATF+3/+4. Noisy little "bzzzzz zzz zzz zzp" sounds normal.
 
#2 ·
Sounds like the range sensor is faulty. It is the switch that lets the TCM know where the shifter is at. If this is the problem, replacement requires dropping the valve body. Although if it is slipping going into 3rd as well, maybe consider an overhaul.
 
#5 ·
I am intimately familiar with low fluid symptoms, having had a leaking seal a few years ago. Typically you don't notice any problem at all, until the first cold morning it simply won't go into gear. You freak out (oh no, a tranny problem!!) and then you rev it a bit, and then it pops into gear finally.

(But I will check the level again just to be sure.)
 
#6 ·
The fluid should not have anything to do with the actual lighting of the gear selector and a ground problem would not vary on lever position. What led me to the range sensor was that it works fine in 3 of the positions and acts up in the other 3.
 
#7 ·
Thanks AndyG: yes, it's a strange mix of electrical and mechanical symptoms. I tried to re-train the tranny a week ago, and as I recall, most of the slipping was actually 1st to 2nd at that time. Does that make a huge difference for you, whether it's 1st to 2nd or 2nd to 3rd?

(And is the range sensor a big job. I have done zero tranny work in my life.)
 
#8 ·
The range sensor is a fairly labor intensive job as it requires dropping the valve body out of the trans. Depending on your love for the car, you may just want to drive it until it dies, or have the trans gone through and be good for many more miles. That would depend on the shape the van is mechanically and cosmetically of course.

Also, I obviously can't be 100% sure the range sensor is the problem, but it sure sounds like it. Other members may come around over the next few days with other ideas as well.
 
#9 ·
Thanks AndyG: The fact that the PRND3L all light up in park and neutral: is that some aspect of the normal signalling protocol, like it's attempting a "limp" mode or something like that?

I'll check back here often, and keep poking around in my service manuals (Chrysler and Haynes) and on the vehicle.
 
#11 ·
Hi all. I just came into work, and thought I would check the fluid. It was the scariest dipstick I have ever seen. There was rusted crud near the top, and as I took it out, small brown-red flakes were falling off, some of them back into the spout.

The fluid itself looked clear, but yellow-brown rather than cherry. Smelled kind of waxy.
 
#12 ·
I would drop the pan to change the fluid and filter, just for the sake of having healthy fluid in there. but it will likely not help the seemingly electrical problem. Might help the slip though.
 
#13 ·
I checked the level, and it was a quart down. One of the reasons I checked was that, indeed, this morning cold the tranny had that tell-tale "wait" period. But I did not expect the mess I found. Anyway, I quickly added a quart of Valvoline ATF+4, hoping to get some improvement in the slip.

Yes, the electrical issues are probably unrelated to the fluid quality, and I'm hoping that those issues are just a dirty connector or something.
 
#14 ·
Er well could be related - a guess. If "crud" is plugging the port for that L/R pressure switch (P1784). Might consider a 3X drain and fill. The tranny holds around 9 quarts. You can only drain 3 quarts by dropping the pan. Recommend getting a pump to pump it out the dip stick instead of dropping the pan 3 times. Or you can pump fluid out the coolant lines and do it all at once. Bit riskier process.
 
#15 ·
Thanks RIP, especially for the specifics about how many quarts to expect. A guy does have to be ready to catch that stuff.

I would rather not take the pan off. Is there a way to suck fluid out AGAINST the filter direction, to hopefully pull some gunk out of the filter? A back flush i guess you'd call it.

(By the way - since adding the new fluid, the shifting seems to hesitate more, maybe needs retraining.)
 
#16 ·
misfiring was causing tranny codes

Hi all:

It seems that the cause of those tranny codes was engine misfiring. After replacing all 6 spark plugs (I had originally replaced only the easy front 3), the tranny codes have never returned. And the 3NL works fine again, both in the way the display illuminates and in the way the gear selector does control the transmission.

Now all I have is a bit of slipping.
 
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