Today my 92 Aerostar with 6 cylinder and auto transmission started jumping back and forth from overdrive to drive for no reason on the highway. It would switch gears at least 5 times in a matter of 15 seconds. The only way to stop it was to shift down into drive and keep it there. I don't think it is the engine because it keeps up with the gears as the gears shift around. All of my gauges are reading normal and I am not getting a check engine light. Any idea what is causing this? Hopefully it is just a sensor that is going bad.

Thanks for your help.

 

How many miles? Might want to check fluid also. My fill intervals confuse me sometimes.

 

1. read codes, may be a stored tranny code that does not set CEL...ECU will error out and command tranny to drop out of OD and/or TC lockup under certain conditions, overheating, slippage, false reported open loop ECU operation

2. how old and what condition is tranny fluid?

3. is your OD select on shifter arm or switch in steering wheel?

4. May be failing OD solenoid in tranny or OD wiring in or to tranny

 

Any and all of the above. Regardless, a very soon complete ATF and filter change should be done on your van, if you determine that the ATF amount is correct. Several years ago, I experienced retarded and lazy shifting into OD with my Aerostar ('87 3.0 V6, A4LD trans) I changed the fluid (using Chevron ATF Dexron III) and changed the screen (filter) This immediately solved the problem. Accelerating from a stop with the floor trans selector in "OD", the transmission would upshift normally through the gears, into "OD" and cruise effortlessly at 65-70 mph. (rear tires, P 215 75R 14) or accelerating from "D", then shifting into "OD" manually (as with accelerating and merging into traffic on the freeway) I could immediately feel the trans engage "OD". no more lazy shifting, and my old ATF did not look noticeably worn, or discolored.

No problems since, and I have always used Chevron's ATF with excellent results in my Aerostar's A4LD transmission...

PS Have a Trans shop add a drain bolt to your trans pan. This way, your fluid always remains fresh. I had it done, years ago, I think it cost $20, for the part and labor. Worth every penny, unless you get rid of your vehicles every 2-3 years...`

 

My 90 Areo did this a few years ago, and after servcing the trans, doing a major tune-up and spending a few hundred $'s it turnned out to be a pulged fuel filter. Now each spring all my rigs get a new feul filter.

 

I had a similar problem with the van ( 91 3l 2wd) jumping from overdrive to drive down the highway. Eventually it started having a hesitation on inital acceleration until it finally would not run at all. It turned out to be the throttle position sensor. It never did turn the CEL on, but the mechanic could read a code with his reader anyways. Since this part is relatively cheap, you could get the codes read to see if this applies. Apparently the switch from drive to overdrive as well as perhaps the converter lockup is electronically controlled, and is relying on this sensor.