ChrisLib

I have been having problems with the overdrive in my truck, trans is a 518 non/lu, stock with 176k on it.I have all the service records from the orig owner and the truck was well cared for, trans serviced approx every 20-30 tho, fluid level is full and fluid looks brand new, nice and red,not burnt/signs of slippage. When i first got the truck (172k?) it would drop out intermittently on the hiway and then pop back in on it`s own, without rhym or reason. I did all the usual stuff, i.e. cleaned & adjusted the tps, ran new tps wiring using shielded cable and put a filter cap on the tps ckt. All of those things had the OD working fine till about 3 months ago, it started dropping out again, except now when it drops out it will not go back in, but when it is working the 3-4 shift is nice and positive, doesnt feel like it`s slipping. It is temperature dependent and will only dropout after the truck has been fully warmed up, or about a 10-15 mile ride at hiway speeds. When it does drop out I can get it to re-engage by pushing on the go pedal a little harder (raising line/TV valve psi?) but evetually it simply stops engaging into 4th. I have re-cked all of the wiring/inputs to the PCM and all ck`s good, i.e tps/speed snsr/crank snsr all ck good. So what i did was tapped the ground side of the OD solenoid and measured with a DVOM. As I had feared, when not in OD I have system voltage present and @ around 35-37 mph the voltage drops to .5 indicating that the PCM is commanding the OD sol to apply. I`m thinking I have some sort of internal hydraulic leak or worse yet the OD assy is going south. My question is, if the OD unit fails will the trans nuetral out until it drops back to third (it doesn`t do this, just feels like it`s downshifting to 3rd when it happens), and if there is the possiblity of an internal leak, do any of you folks have an idea where to look. I was looking thru my FSM and I can see where the the OD solenoid gskt,VB separator plate, and the 3-4 accumulator can be a source of leakage but i don`t have much experience with these units so I would like an "experinced" opinion of where I might concentrate my efforts. Other than the OD problem the trans works fine, no slippage etc. TIA!!

DODGE 92

let me guess drops out between 80 and 90 km/h drops back in if you go to 100 km/h

ChrisLib

What it`ll do is after warm at hiway speed (55 mph n up) if I have to back out of the fuel it`ll drop out, then for a few miles I can get it to go back into 4th by mashing the pedal but evetually it just stays in 3rd.