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Thread: Auto trans not shifting at all

  1. #1
    Junior Member
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    Auto trans not shifting at all

    I tried to get the D rolling after the 10 year sleep. Rebuilt entire fuel system. Engine is running, changed trans fliud and filter. Started and Tried to shift into gear and nothing. The gear shifter moves freely thru all gears.

    I dropped the trans pan to verify the linkage is moving, and it is moving freely. At this point it does not look like it is in the linkage. I have the pan open right now.

    What can i check with it open what would keep it from shifting at all. I did try shifting to neutral, then turning the rear wheel. It spun. Then shifted into park. I could still turn the rear wheel,but it was difficult. Diffenant made a change in the trans.

    What do i need to check next?

  2. #2
    Senior Member
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    First thought even just looking at your thread title is that it's a shift computer governor problem.

    Curious what exactly happened when you tested it out and it wouldn't change gears? I ask because if the shift computer fails, it can lead to various shifting problems with particular characteristics.

    If you started up the car, put the gear shifter in drive, and there was no forward power, I'd say that could be a plugged filter and it's not letting you get the fluid pressures needed in the trans.

    If you said that you fired it up and when trying to pull away in drive, the car slowly moved forward, but without a lot of power, it might be that the transmission is stuck in 3rd. If it is stuck in 3rd from a stand still (and not in 1st) it might be as simple as the fuse for the shift computer is bad. That is fuse #13 and it is 10 Amp.

    If you can get driving in 1st, but then the car doesn't shift normally and revs high before thundering into 2nd (or something similarly not right about the shift points), it might be telling you the shift computer wiring got melted against the exhaust crossover pipe and has fouled up the signals between the various points on that wiring harness. Inspect the wiring to see if anything appears melted. It could also mean the inside of the shift computer box has problems and needs to be rebuilt. Not cheap to do, but a known issue and service that the vendors can do for you.


    Sept. 81, auto, black interior

  3. #3
    Delorean Guru
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    If you have verified the shift linkage is moving then put the pan back on, fill with ATF and check the line pressure as per G:05:03. If it still won't move you probably have to take the trans out. BTW, how much debris was in the pan, what color was the fluid and how did it smell?
    David Teitelbaum

  4. #4
    Junior Member
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    More info.
    The car only has 10000 miles and is all original. I'm quite sure it had the original trans fluid in it. It was driving fine when parked 10 years ago.
    I could start the engine. When put in any gear, D, 123 or R. No movement. Engine would just rev up. Just as it would in park or neutral.

    There was no debris in the pan. The fluid was dark, but had no unusual odor.

    Is there a way to test the governor prior to putting the pan back on? Also the two solenoids?

    Once i put it back together, ill test the pressure, but want to test what i can before putting it back together.
    Thanks for the help.

  5. #5
    Administrator Ron's Avatar
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    Quote Originally Posted by YJK View Post
    I did try shifting to neutral, then turning the rear wheel. It spun. Then shifted into park. I could still turn the rear wheel,but it was difficult. Diffenant made a change in the trans.
    Normally, you should be able to spin the wheel with it jacked up (one a bit easier than the other), unless someone holds the opposite wheel...
    Was there a "change" in the trans itself??

    =====

    In addition to the other advice- If it doesn't pull period, it might be the GC (Governor/Shift Computer) -- It can call for an undefined mode...Basically, when the solenoid that should never be powered by itself is the only one powered (Or, the other is stuck!). If there was nothing significant under the pan, I'd try pulling the fuse and see if it goes into 3rd first....An easy way to answer most of the GC problems mentioned too. Rare, but so are problems with these solenoids.

    EDIT: Just saw your last post...
    If the dark fluid was not caused by clutch material and the harness looks ok etc, I'd suggest you (at least temporarily) put the pan back on and test the GC. An easy way to do it with two light bulbs is located HERE in the Resources Section.

  6. #6
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    I have to go get more trans fluids today, ill try the fuse to see if it acts differently, once back together. On the fluid color, im sure its dark from age. I could not feel any grit in it and the magnet had no metal at all on it. I'll double check the harness also. Ill check pressure once back together also.

    Is there a way to cycle the GC? To verify it works prior to putting the pan on and adding fluid.

    Can the GC and the solonoid be cycled by hand?

    Thanks for the help. It will be this evening before i get a chance to work on it again.

  7. #7
    Delorean Guru
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    Forget the Governor. No way it can prevent the transmission from moving the car in every gear. It takes oil pressure to move the car so that is something to check for but if it doesn't move it is probably broken inside and will have to come out. Take the filter off and leave it off for now, put the pan on and fill with ATF. Give it a try and if it won't move the tranny is coming out. I would still check for pressure because it will help in narrowing down the problem.
    David Teitelbaum

  8. #8
    Administrator Ron's Avatar
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    I think David is right since I know he's been playing inside of them too, and, I rebuilt mine, but haven't looked at the internal pluming at depth, only the GC.
    So if the one solenoid remaining in off position doesn't affect the other pressure circuits etc, the only cycle you really need to diagnose the trans not pulling at all is the one when everything is off. If you pull the fuse (and filter) and the trans doesn't pull, you'll probably be pulling it. Otherwise, you could ground the terminals at the same block used with the test lights mentioned in the link I posted above. ...Note you would use two Ground wires on the two terminals, according to the logic chart in the updated schematic I posted there yesterday.

  9. #9
    Delorean Guru
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    While anything is possible, it is very unlikely the GC is commanding the solenoids into that illegal state. On a trans Dave Swingle worked on it had very unusual shifting which turned out to be a blob of silicone plugging up one of the solenoid valves. As said, pull the fuse, the filter, slap the pan back on, fill with ATF and hope for the best.
    David Teitelbaum

  10. #10
    Administrator Ron's Avatar
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    Quote Originally Posted by David T View Post
    On a trans Dave Swingle worked on it had very unusual shifting which turned out to be a blob of silicone plugging up one of the solenoid valves.
    ...a 3rd valve!

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