I have the A518/46RH transmission on my van, which is the 3 speed plus overdrive trans. One thing I have noticed is the 4th gear has never worked on this van in the 18 months I have owned it.
Initially I thought this was just because the trans was failing. Then last summer I replaced the trans with a Chrysler-rebuilt unit. Still no 4th gear.
I was told at a shop (who was doing some other work on the van) that they noticed that some piece or pieces to what they called the “kickdown assembly”, pieces which apparently keep the kickdown assembly correctly mounted to the side of the transmission, are missing. The mechanic noted on his report, “Found shift detent rod unhooked from transmission which could cause throttle to stick.”
Can someone translate this into english? Thx 
Anybody have any thoughts on this?
Well, it turns out overdrive is now working, apparently as a result of recently completed electrical repairs related to a burned fusible link in the blower motor circuit. I was driving 65mph on the highway last night, and it seemed that the rpm’s of the engine were consistent with the trans being on overdrive for a change. To test, I pressed the “O/D Off” button, and sure enough the trans downshifted into 3rd gear. I pressed the O/D Off buttion again, and the trans returned to overdrive.
The weird thing is, whenever I start out from a dead stop and keep track of the number of gear shifts, I sense only two shift points. The trans shifts from 1st to 2nd around 10-15 mph, and then shifts again straight into OD at around 35 mph. There is no separate shift from the regular 3rd gear into into overdrive. I always thought the trans should shift through all its gears on the way to overdrive, as do all my other vehicles with overdrive – the trans cycles from 1 to 2, 2 to 3, and then 3 to o/d (at around 45 mph).
So, is this situation unique to the Dodge A518 transmission, or do I still have a problem?