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1998 Chrysler Sebring

I replaced the computer on my 1998 Chrysler Sebring 2.5L 6 cyl. Everything works except the OverDrive (OD) indicator on the dash does not come on and the car will not down shift; it shifts early, then stays in “second” and will not down shift at 40 mph as it should. Is this a computer programming problem or something else. Thanks

Think of your car as having five gears, like a standard transmission might give you five gear choices. Overdrive in this system is the highest, the fifth gear. In this gear you would be able to drive on a flat road at almost the lowest possible rpm’s at highway speed, which is very good for your engine and fuel efficiency.
So if you have only two gear changes up to 40 mph, you should not drive the car at all unless you are only going to go as fast as, say, 30mph.
I don’t know what was allegedly wrong with the car that the computer needed to be changed, but it has nothing to do with your current problem. One of three things are going on. Cheapest to worst are: a)You are low on transmission fluid, and/or you need a change of fluid and the screen replaced. b)You have a vacuum leak to your transmission and c)You have a bad transmission.

where did you got that ECM from ? It looks like the transmission is in limp mode.

I got it from another car of the same year, make and model. The car would not start with the old computer. I put the new one on and it starts, but doesn’t do the final shift.

It does sound like the transmission is in ‘limp’ mode. Take it (slowly) to whatever independent transmission shop is rated best in your area (avoid AAMCO or Cottman like the plague), and have the transmission computer scanned for codes. This will tell you what is really going on here. It may be a result of your changing the PCM, or it could be a coincidental failure, but you’ll just be guessing until you have the tranny checked.

Good luck

If you did not have this problem before you replaced the PCM, the problem is almost certainly related to the PCM. The PCM actually DOES control your transmission as well as your engine. You should make sure the donor car had the same transmission as your car. If it did not, that could lead to problems like this. If that’s not the case, you may need to have the new PCM reflashed to work with your car. I would follow others’ advice on having a transmission shop look at it, though, but if this is a new problem that only developed when you replaced the PCM, logically, the PCM is related to the problem.