Car won't stay in gear

[mattgw86]

My '94 Town Car keeps falling out of gear. It'll usually happen while I am at a steady speed, but it still happens sometimes while I'm accelerating. It feels like the torque converter is slipping and disconnecting. I was told that flushing the trans should fix it, but the fluid seems fine. It only has 79000 miles on it. I can't seem to find a place with an OBD I scanner either, so I can't check it for codes. If anyone has any ideas or knows how a trans flush would help, please explain to me.

[1987cp]

Potentially dumb question, but have you checked the adjustment of the gear-selector linkage? Sounds to me as though "D" (or OD on an AOD) on the stalk may be too close to "N" on the valvebody, in which case a couple minutes spent adjusting the linkage will cure the problem.

Of course, if the transmission is slipping, that's bad news. I'd definitely check the linkage adjustment first!

[87_crown_vic]

have you tried putting the car in drive instead of overdrive? i use drive all the time except on the hwy when i get to speed i shift to overdrive

[mattgw86]

There's a button on the shifter to turn off the O/D. It will still slip and fall out of gear when the O/D is off.

[Spaz]

my '94 grand marquis had this issue for 7 years but never threw a code and was so intermittant that it was impossible to diagnose it at the tranny shops when it happened the first time. when i started driving it full time this summer i researched it and it was the MLPS (manual lever position sensor) bolts to the side of the tranny case under the car part costs ~$50 takes 30 mins to replace. the original sensor design on those early AODEs have a harness connector that can get corroded try that before tearing into the tranny. it woud be wise to change the fluid if you havent in the past 15000mi. don't flush it just have the pan dropped and the filter and gasket changed. that should get the Town car running like new.
Since i replaced the MLPS on my '94 marquis i have driven 2500mi and havent had any issues at all from the tranny, and the mileage has gone up, i guess from it not dropping out of gear. It definately is the MLPS if the tranny drops out of gear but when you slow down to ~25mph and try to accelerate it gets 1st and nothing else but drops to N when you let off the gas. In the meantime i suggest that if it gets really bad put the shifter into 2 so the car can br driven up to 45mph locked in 2nd, and DO NOT USE THE CRUISE CONTROL. IF THE TRANNY DROPS OUT OF GEAR WITH CRUISE ON, THE CRUISE WILL FLOOR THE THROTTLE AND BLOW UP THE MOTOR

[mattgw86]

Sounds good, I'll check that out tomorrow. I don't have to worry about the cruise, it doesn't work anyway, that's another project.

[1987cp]

There's an electronic sensor to sense the position of the gear selector? Is that in lieu of a mechanical linkage, or just some sort of retarded - sorry, redundant - electronic control thingy?

[Spaz]

from what i understand, on the AODE the MLPS serves as the neutral safety switch and as the device that gives the signal to the transmission which range the driver has selected
I'm sure many '92-'95 AODEs have been rebuilt for no reason because of a malfunctioning MLPS. I had to really talk my mechanic into replacing it, he was ready to tear into my tranny for a rebuild, and when i left the shop he was expecting me to come back in an hour later.

[1987cp]

Peculiar. Useful piece of information, there!!!

[seneeb]

yes, there's a sensor that tells the pcm where the lever is.

the issue with the cruise control can still happen even if the system does not work. what happens is brake fluid seeps through the deactivation switch and can short the harness side connector causing either the fuse to blow or burn the wire. the current "fix" is to simply unplug the deactivation sensor connector and tape it off until parts are available, which in theory should be by the end of this month

[Spaz]

yes, there's a sensor that tells the pcm where the lever is.

the issue with the cruise control can still happen even if the system does not work. what happens is brake fluid seeps through the deactivation switch and can short the harness side connector causing either the fuse to blow or burn the wire. the current "fix" is to simply unplug the deactivation sensor connector and tape it off until parts are available, which in theory should be by the end of this month

read my post, i wasnt talking about the recall issue, i was talking about how the cruise doesnt realize that the tranny has dropped out of gear all it knows is that the amount of throttle that it was giving wasnt increasing speed so it gives more until the throttle is floored and the engine is bouncing off of the rev limiter because the mlps decided to take a nap

[85crownHPP]

... DO NOT USE THE CRUISE CONTROL. IF THE TRANNY DROPS OUT OF GEAR WITH CRUISE ON, THE CRUISE WILL FLOOR THE THROTTLE AND BLOW UP THE MOTOR

unless you hit the brake pedal in time...
my 85 got bumped into neutral with the CC on once... like you said the RPMs started to shoot up, but since I quickly instinctually put my foot on the brake, it shut off the CC before it wound it out

[1987cp]

So, it sounds like it's a lot simpler and safer to just not have one of these MLPS doodads.

[Spaz]

well after '95 or so they redesigned the harness connector and that really ended up fixing the problem. I'd much rather have a mlps go out than have a TV cable bushing fail and burn the trans. After 7 years of having a bad MLPS, and as a result popping into neutral countless times after i finally replaced it this summer my marquis is running like it did when it just left the factory.

[seneeb]

read my post, i wasnt talking about the recall issue, i was talking about how the cruise doesnt realize that the tranny has dropped out of gear all it knows is that the amount of throttle that it was giving wasnt increasing speed so it gives more until the throttle is floored and the engine is bouncing off of the rev limiter because the mlps decided to take a nap

my appologies

i was barely awake hehe