electronic shift transmission/speedometer

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Jun 9, 2003 | 10:02 PM

jimmick

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Joined: Jun 2003

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electronic shift transmission/speedometer

I have a '93 'Rostar (my name for my Aerostar). I have the electronic shift transmission.

A condition that started as a extremely intermittant nosedive of the speedometer, that slowly became more frequent over about a year.
Everytime the speedometer dipped more than 10 mph below the actual speed, it triggers the transmission to downshift. This became erratic in a very short period of time.

Of course, the local AAMCO tried to sell me an overhaul, which I declined. The speedometer has now ceased working, and the tranny won't shift to OD. I changed the speedometer cluster in the dash with no success.

Anyone out there experience the same thing.

Jun 11, 2003 | 06:10 PM

Mikeman

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Joined: Apr 2000

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From: PNW

electronic shift transmission/speedometer

I've never had the problem, but it won't stop me from offering a suggestion. It sounds like the speed sensor is bad (or the wiring). Speed is used in determining shift scheduling, so that's probably why it won't go into OD. You'll have to check the circuit to see where the problem lies. You may also want to remove the sensor and see if it has picked up any metal shavings. It's essentially a magnet so if there is any metallic gunk in the oil, it could end up stuck to the sensor.