1994 Accord Overdrive

This is my last ditch effort to see if I can determine if there is anything short of a transmission swap that will resolve this problem I am having. I have a 1994 Accord LX 4 Cyl with Automatic. She has 180,000 miles on her and all service has been performed since new at the intervals set by Honda. We take off on an expressway, and the car shifts into second, then third, then fourth just fine. Once the car gets up to about 60 mph and levels out, it drops out of overdrive (4th) and into 3rd. Pressing the gas gets the car to lock into overdrive again until things level out and it drops out into 3rd again. On longer trips this is annoying. I have no D4 light, it comes on on very rare occasion, and when it does, the tranny stays locked in OD. I've cleaned and checked the Shifter position switch, and the shift and locking solenoids. All are working fine. I took it to the Honda dealer who has had it for 5 days. They tell me that the car is showing no error or problem codes, and have confirmed that what I have checked is working. They seem to think its an internal problem where the transmission is losing pressure. This could be worn and/or hardened o rings, or varnishing of the fluid due to age causing binding of some small piston or other similar part. (Fluids is fresh and was changed on schedule). Has anyone else experienced this problem and successfully fixed the thing short of a tranny rebuild/swap?

You got to have a D4 light for it to lockup. In the 4th gen. Hondas (90-93), the shifter switch provides a ground for the D4 light and the ATU. Check the wiring diagram for your model to see if it is the same. If it is, at the shifter switch, ground the grn/blk, I think, and see if the light comes on. If it does, you still have a switch problem. The clue to this problem was your statement, that when the D4 light comes on, it works OK. Keep us advised on this problem.

I have a shop manual and can locate and check the ground. I'd be happy if it was that easy. The dealer told me they retrieved no codes when they hooked it up to diagnostics. This tells me all of the components are working correctly. They had no clue on the D4 light. The shop manual points to the Shifter Position Switch, which I cleaned and checked thoroughly, an open lead in one of several dozen curcuits, or the TCM. The problem is, if it was any circuit or the position switch or TCM going they would all cause a code. So its confusing even the dealer techs. I'm thinking that it may be just some varnish inside and maybe a Lock Up solenoid filter screen thats gummed up. Its cheap enough to replace the filter gasket, and flush and refill the fluid to see what happens.

I don't think a not made connection will cause a failure code, because D4 is not an always selected position. Try to make that D4 light illuminate and I think you will solve your problem at least it will in a 4th gen accord. Keep us advised.