1996 Chrysler LHS itermittant down shift with transmission

ALEXANDERCOSTAL

MEMBER
1996 CHRYSLER LHS
3.5L
V6
2WD
AUTOMATIC
250,000 MILES

96 lhs automatic transmission will down shift hard at about 45mph and wont shift back up into higher gear while car is still moving down road unless while still moving I put in neutral cut ignition off then restart and shift back into drive it takes the higher gear until I slow down again or stop. Problem is intermitant as it doesn't do it everytime I drive the car. Had transmission flushed some improvement in operation but problem still persists now and then. Was wondering what can be done to fix this problem?

4 Replies

CARADIODOC

MECHANIC
33,741 POSTS

Defaulting to second gear is "limp mode" which allows you to drive slowly to a repair shop without needing a tow truck. You already know that you get it out of limp mode by turning off the ignition switch and restarting the engine. When this occurs, it is in response to the Transmission Computer detecting a problem. In this case it is most likely to be related to one of the speed sensors, but to know for sure, the place to start is always by having the diagnostic fault code(s) read. Fault codes never say to replace a part or that one is bad. They will indicate the circuit that needs further diagnosis or the unacceptable operating condition.

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Wednesday, December 17th, 2014 AT 6:13 PM

ALEXANDERCOSTAL

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3 POSTS

Thanks I have some experience at working on vehicles in a dealership environment and a few shops over the years. I was thinking the same thing earlier today about the speed sensor causing the problem but needed an opinion from someone who has more experience with this type of issue. I will pull the codes and see if suspicions are correct and go from there. My own vehicle and don't want to replace parts blindly without understanding why its happening. Always learning something different. Thanks Again

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Wednesday, December 17th, 2014 AT 6:50 PM

ALEXANDERCOSTAL

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3 POSTS

. Pulled codes low speed fan circuit, multiple cylinder misfire detected, and cylinder 5 misfire detected 3 codes in all but nothing pertaining to transmission trouble unless I need a different setup to pull codes for transmission.

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Wednesday, December 17th, 2014 AT 7:29 PM

CARADIODOC

MECHANIC
33,741 POSTS

Yup. You're in the Engine Computer. You need a scanner that can access the Transmission Computer. It is usually referred to as the "EATX". Electronic automatic transmission controller.

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Thursday, December 18th, 2014 AT 9:13 PM