My truck on longer journeys usually has my trailer hooked up and I lock out OD, everything has been fine also I tend to lockout OD around here also as it means the convertor is locked for much longer so revs down and MPG up, it can trundle along just over our lowest built up area speed limit of 30 just nice, pretty flat here.

Yesterday I went to fit a turbo boost sensor on a Volvo loading shovel, already visited to diagnose and was 100% sure so no need for my trailer just the part and a 8mm ratchet spanner and a small screwdriver

 

Noticed the change from 3rd to 4th was harsh and not what it usually is bearing in mind It may not have done that upshift for a bit, last time I recall was towing on the motorway downhill so throttle backed off anyway, I turn on OD in this situation then off as soon as the downhill is done when towing.

Checked for codes this morning and there was only battery voltage low, this was from when my alternator  resettable breaker popped the other week while jump starting a Peugeot Boxer,  I did disconnect the quad before the jumpstart,.

I cleared the low volt code and ran the truck, no active or stored codes in Engine ECU ,PCM , ABS or Body.... nothing and this is with a SO Modis at 2018 software so there is no codes.

The truck runs and shifts ok other than hard into OD, trans temps yesterday at 50 miles round trip was around 120f give or take

My next thing is to turn the quad down from 9 to 6 and see what that does, this could well be the cause thinking about it

 

Other than that I may have to drop the pan any other suggestions ????

26 minutes ago, Mopar1973Man said:

Remember iQuad is only calculated for gear position based on tire circumference math not actual.

Ahh that's something I didn't know, so highly possible it's just a calc that puts the LU light on in 3rd

I can change the tire size enough to make mine appear to be any any gear I wish. Being the PCM does not communicate gear position or even able to detect it there is no way for the ECM to have that info either. Kind of like the MPG display is all calculated from the fuel data, offset percent, and speed data. Accuracy of any calculated info requires the info in the setting to be accurate so the calculated is accurate as well. Now another thing too a lot of people assume the timing value display is actual timing of the engine which is is while the timing piston is working but as soon as P0216 code is thrown you looking at commanded timing and the piston could be full advanced ot retard and still display timing commands as usual.

On 2/20/2022 at 9:56 AM, Mopar1973Man said:

3rd LU will only happen in the the OD switch is OFF. Even my old 1996 Dodge was that way.

I would have sworn this changed around 2000 or 2001, but I don't remember ever looking it up in the manuals, either.  Hopefully I can find some time in the next few days to research it before I completely forget about it...

I think the only way to change it is to put a shift kit in that allows 3rd lock up without OD being off.. Been a while since I was looking at transmission stuff for a second gen.. 

Just now, Silverwolf2691 said:

I think the only way to change it is to put a shift kit in that allows 3rd lock up without OD being off.. Been a while since I was looking at transmission stuff for a second gen.. 

I haven't really looked into it, but I thought the PCM was "upgraded" or something with better logic/capability/what-have-you to allow it to utilize 3rd gear lockup.  The FSM says the PCM allows it under certain circumstances, then gives as an example the OD being switched off - I have not yet looked for what other circumstances may or may not exist.  And for all I know, they other instances may only apply to those equipped with gas engines.  Would be interesting to find out, but not sure how much use it would be to me!  Just for knowledge sake.

Hard part is, the 46/47/48RE series for Rams, and possibly some of the other models of that era, are more or less still a torqueflite 727 with an electronic overdrive bolted on the back and electronic lock up (I think.. not 100% on that last part). its still a mostly hydraulically actuated transmission. Even more so for the 46/47RH transmissions.

 

I did some digging a long time ago when I had my black 1500 about what to do to make the trans last. I don't know specifics, like how lock up is actuated or how all the solenoids work together to shift the thing.. I do know you can put lock up actuators and an overdrive onto an actual 727 and get some fuel mileage out of it, its not cheap though.

 

I swear though that the transgo shift kit I put in that 1500 said that it allowed 3rd lock up..

Just looked, I think it was one of the other kits and I was just remembering reading about it. It would still need a manual lock up controller to actuate it, and it Could go to 1st gear lock up..   

The lockup is just a wire to a solenoid/piston to apply the clutch in the torque converter.  You can put a toggle switch on the dash and make it lockup at your pleasure.  I believe it's the orange and black wire - confirmed it's wire K54 on the Factory Service Manual page 8W-31-3.

 

Right or wrong, in my mind I assume it's like an electric PTO on a garden tractor. This is wrong.  Page 21-778 says how it is done. The TCC solenoid (operated by wire K54) controls "venting" of the hydraulic fluid to the TCC; when vented, the clutch is disengaged.  This seems strange to me as written, if it's a Normally Closed solenoid.  That would mean if the wire was broken (or eaten by a squirrel...) that the converter could never unlock.  I would think applying power to the solenoid would operate it, allowing fluid to apply the clutch - but my thoughts on automatic transmission sequence of operation is of zero (or even negative) value!

Edited February 21, 20223 yr by LorenS
Added page numbers.

There is a strictly hydraulic valve in there that prevents downshifts when ever the converter is locked. The PCM has to electrically unlock the converter clutch solenoid before a downshift can happen. many shift kits have a bigger port in the separator plate for firmer OD and TC lock. There's also an accumulator/valve for the OD. It's very common for the spring on that accumulator to break. Most people don't notice when it breaks.