I have a 1998 12 Valve 3500 Ram. My 47RE finally bit the dust and I bought a rebuilt tranny and new TC. The truck is totally stock - no modifications, no mystery switches etc.
I put the new tranny in this afternoon, filled it with fluid and took it for a drive. All the shifts up to overdrive worked smooth and as they should. Only problem is, the TC will not lock up and OD will not engage until I hit over 60 MPH. The old tranny did at around 50 mph and lower on light throttle.

Any thoughts on what I need to check, adjust or ? The only thing I replaced from the old tranny to the new is a sensor/switch in the tailshaft as the new one did not have it. Not sure what that one is? The front 3 contact plug and the top 8 contact were the same.

Thanks
Tom

 

I am no tranny expert but I would check TPS voltages. You might try getting the TPS idle voltage down to .5 volt, the higher the tps voltage the later the shifts. My guess is the new trans has higher line pressures and that is effecting shift points.

 

Check the throttle valve cable adjustment. Some people call it a kick down cable too. Goes from the trans ( the smaller lever on top of the shifter lever 0 to the throttle linkage at the pump. There is an adjustment at the pump end. Basically, unhooked at the pump end you want it to line up with the ball that it hooks too . Not shorter or longer, right in line- then hook it back up. Sounds like it is too tight ( or short). Should help your problems. Did you put a new cooler on? I'd definatley take out the check ball in the drainback valve in the cooler line too!

 

Thanks for the suggestions. VZDUDE, when you say the "pump end" are you referring to the bell crank that the throttle cable is attached to? Because that is where the throttle valve to trans cable is on mine?



Thanks
Tom

 

Exactly! ^ Adjust it there.

 

I just tried adjusting it per specs. Still no lockup or overdrive. I then tried on both sides of the adjustment (loose and tight) - still no go. I guess my next try is to install a mystery switch and see if that locks up the TC.

Is there a manual way of forcing overdrive to come on?

Thanks
Tom

 

May be an electrical problem. Any codes? Check the plug in on the driver;s side of the trans. Everything get hooked up inside the pan?

 

Grounding the brown wire pin 55 I think will do it.

 

Thanks to everyone for the suggestions. Before the old tranny bit the dust, I had bought all the parts for the mystery switch and the linear pot for controlling when the OD kicks in. Tonight, after rechecking everything, I put together the switch and took the truck for a ride. Switch worked like a charm Locked up the TC in any gear, but still no overdrive until way past 60.

Came back and soldered up the linear pot and hooked it up to the contacts from the TPS. At first, same results. Then, while driving under light throttle in third, with the TC in normal (not switched mode) I started to gently turn the pot a bit at a time. All of a sudden, lockup and overdrive at about 55mph. After playing with the pot a little more, I am now able to lock the TC and hit overdrive at 45mph. Not ony that, but it stays in overdrive to just under 40mph which is great for the hilly country I drive in.

So, with the combination of the mystery switch and the pot, I now have total control of the TC lockup and the OD entry. Now all I have to do is take all the mess of wiring and switches and build it into a little box. I don't know what I would have done without this group :-))

I guess the TPS and the tranny had some sort of compatibility problem or the TPS decided to flake just when the new tranny went in?

Thanks again to all.