1994 Chrysler New Yorker auto transmission/downshifts by itself

SPANKY123

MEMBER
1994 CHRYSLER NEW YORKER
3.5L
V6
2WD
AUTOMATIC
165,000 MILES

The car downshifts from overdrive to second, for no apparent reason, I have changed the output sensor on the tranny, and the cruise, control relay is fine, also cruise control isn't working, fluid is fine, no burnt smell. The problem has to be electrical, because I can be going anything over 20 mph I shift the car into neutral, turn the car off, restart, put it in overdrive and it's just fine till I stop or something, maybe turn a corner not sure why or exactly when it happens. It's driving me crazy I love this car. Plus can't afford another one.I had a 93 concord that did the same thing, got rid of it.

1 Reply

CARADIODOC

MECHANIC
33,916 POSTS

The electrical part is because the transmission is computer-controlled. The first thing you need to do is have the diagnostic fault code(s) rear and recorded. That will tell you the circuit or system that needs further diagnosis or the unacceptable operating condition.

Also, most scanners will display the "clutch volume index", (CVI). That's a set of four numbers corresponding to the number of CCs of fluid it takes to apply each clutch pack. Based on those numbers, an experienced transmission mechanic can tell you the percentage of life left in each one. Based on the mileage, it's a good bet there is slippage taking place in one of them. That will set a gear ratio fault code.

You're correct that turning the ignition switch off, then restarting the engine gets it out of limp mode. An easier way to buy yourself some time is to accelerate a little harder than normal to delay an up-shift, then let off the gas to reduce the torque on the clutch packs so they don't slip during the gear change. Once they're locked up in the next higher gear, you can accelerate and do the same thing for the next gear.