Need help with transmission issue

girdnerg

girdnerg

1st Gear Poster
Joined
Sep 24, 2023
Messages
45
Location
Eastern Oklahoma
Vehicle Details
1994 Ford Thunderbird LX 4.6L V8
Country flag
Transmission is a j-modded 96.

It will just randomly come out of gear. It seems to happen above 40 mph.
If I have the cruise control on, the engine revs until I hit the brakes. I let off the gas for a couple of seconds, then the transmission re-engages and acts normally for the rest of the trip.

It does not happen every time I drive it.
Would a weak alternator cause any of this?

Any ideas?

Thanks,
 
4th gear going to neutral can happen with a 2002 trans in an older car, dit if it's an original, I'd say the direct clutch is failing. An alternate explanation is the mlps coming un alligned, or a wiring issue shifting it to second, which overruns a clutch, and feels like neutral until you slow down enough to re-engage the clutch. I've had both issues, lol.
 
This only happens with the cruise control on?
 
It does it with or without the cruise control being engaged.

Yes, it completely disengages like I put it in neutral.
 
Do you have any capability to read live data from the PCM?

If the MLPS or shift linkage is at fault or out of adjustment it might be "halfway" between N and D when you put the shifter into D, and occasionally dropping to the N side of that midpoint. Might be worth a second look, anyway.

If it were fluid starvation it would shift from 4th into 3rd. If it were the TPS or BOO switch it would unlock the converter.
 
I have a code reader that provides some live data. What info do I need?

First thing I checked was the fluid level, which is fine.

I'm not a very good transmission mechanic. The j-mod is the most in-depth thing I've done to a transmission.
 
Have you inspected the MLPS (Neutral safety switch) on the trans for any cracks? If water gets in them they can create issues. Happens frequently if the switch is old.
 
If you can, just monitor for the commanded gear for now. If it's dropping into neutral because of the MLPS, it will show up on your scanner. You might even catch it before you start moving.
 
supergordo said:
Have you inspected the MLPS (Neutral safety switch) on the trans for any cracks? If water gets in them they can create issues. Happens frequently if the switch is old.
Click to expand...
No I have not.
But this is what I'm asking for. I really don't know where to start and this seems like a good first step
theterminator93 said:
If you can, just monitor for the commanded gear for now. If it's dropping into neutral because of the MLPS, it will show up on your scanner. You might even catch it before you start moving.
Click to expand...
I'll do this the next time I take her out.

Thank everyone up front for your help. I'm a transmission newb.
 
Another thing worth checking is the wiring harness that is sitting on the transmission that plugs into everything on the trans. Age and exposure to oil will make the wiring insulation come off. Sometimes you can get a couple wires touching each other that shouldn't. Worth taking a look.
 
Sorry it took so long. Have had some bad weather for the past week here in Oklahoma.

Had a sunny day today and this is what I found.

IMG_20240508_160949036_HDR.jpg


Any advice on brand or does it matter?

Anything out of the ordinary when changing the MLPS?

Thanks. You guys ROCK!
Rob
 
Wow, I never heard of that happening! :eek:

I'd stick with a Ford replacement. The gurus can give you better advice than me, I know it needs to lined up properly.

Joe
 
Hey Joe.

This is the part # I found F5AZ-7A247-AA. So far the ford websites say discontinued. To late to call my local dealer today.

RockAuto has 2 that have a 3 year warranty
STANDARD MOTOR PRODUCTS NS95 wholesaler closeout @ $40
WVE 1S5325 regular price is $60
 
It's not the easiest thing to align. Make sure it's got the weather seal. To change mine,I had to depin the connector, place the seal, then put the pins back in. The factory connector is not sealed, and that's a problem. There's a pair of lines on the manual lever and mlps, that have to line up. The reverse light can help check the alignment.
 
Put the car on jack stands. Put it in Neutral. Then remove the switch. Line up the lines on the new switch before you get back under the car. You can even mark the lines so you can see them better. Then Install the switch onto the trans and put the bolts in. You shouldn't have much trouble.
 
It looks to me like my biggest problem is the exhaust being in the way. All joints are welded so I have to break hangers to drop it. I'll try to do it with it in place for a minute, but will drop it if I have to.

New MLPS will be here next week.

Thanks for the replies,
 
girdnerg said:
It looks to me like my biggest problem is the exhaust being in the way. All joints are welded so I have to break hangers to drop it. I'll try to do it with it in place for a minute, but will drop it if I have to.

New MLPS will be here next week.

Thanks for the replies,
Click to expand...
You don't need to drop the exhaust. I've done it many times. Those are small bolts. You can crack them loose with a 8mm combination wrench and back the bolts out with your fingers. There is enough room to take the switch off without messing with the exhaust.
 
I thought about the cracked mlps. There is nothing to do that, unless a large rock bounced into it. If there's no impact marks, It likely filled with water, froze and broke. Otherwise, I'd expect the trans case to be cracked between the mounts.
 
Gordo, thanks for the tip.

Grog, the car lives out in the weather in the driveway. We get really cold and hot weather extremes. My exhaust is right below it and has no damage to it or anything else. Heck, I could have cracked it when I did the body swap a few years ago and then the weather took over like you suggest. We'll know more when I get it out and can inspect it.
 
I think the issue with the exhuast is due to it being aftermarket exhaust. On the stock exhaust you can replace that switch but it sounds like his is a little different our aren't welded into place so he may have to lower the exhaust to get to it. but I believe he is on the right track to fixing his issue.
 
Yes, I have an aftermarket exhaust. What I mean by welded together is that there are no joints to unbolt. I cannot take down a small section of it. It's either all or none. Even then, I have to break off the two hangers by the transmission to get it down. Not mechanic friendly but the only place I can have an exhaust leak is at the manifold.

New MLPS showed up today. There are 2 different sizes of shims in the package. I won't be needing those will I?

Grog6 said:
It's not the easiest thing to align. Make sure it's got the weather seal. To change mine,I had to depin the connector, place the seal, then put the pins back in. The factory connector is not sealed, and that's a problem. There's a pair of lines on the manual lever and mlps, that have to line up. The reverse light can help check the alignment.
Click to expand...
A new connector came with MLPS. It has 2 seals. The one installed has holes for 8 wires and the other only has 6. Is this the seal you are talking about? Depending on the pigtail length, this might be the hard part.
 
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Yes, that's it. I filled the extra ones with rtv. :) It's all to keep water out; the og ones were prone to water ingression changing the values of the resistors. The mlps is apparently read continuously, so if it changes, the trans tries to shift to match. Thankfully, all it can do without moving thr shifter is neutral, drive and second. If you go to second, it feels like neutral, until you slow down enough to reengage the one way overrun clutch. Then you're in second.
 
Been driving the car for a week now with the new MLPS. That seems to have been the issue. I have had zero issues so far.

Grog6, that pigtail was a PIA to work with but I got-her-done.

Thanks to all who helped!
 
Happy you got it fixed, and that you found us!
Drive it in the rain, before you completely trust it. As long as the seal is there, and dielectric grease, it should be fine.
 
Sound good. There is a chance of rain every day for the next 9 days, so I should get a chance to verify that.

I have been through the automatic car wash. It is touch-less, but has a belly washer.
 
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