87k on the clock. Recently did a trans pan drop and filter change/fluid fill w/ATF+4 as part of a maintenance rodeo from this van sitting for umpteen years and barely being driven. Recently coming back from a 500 mile road trip, (which was probably the first time this van has been driven at highway speeds in several years) and lost overdrive/TCC engagement close to home thankfully. I did NOT adjust the bands as I didn't know that was a thing or possible until researching this issue.

Here's where I'm at and looking for anything I may have missed before dropping pan (again) and replacing the OD/TCC solenoid and adjusting bands:

• 1-2-3 shifts are spot on w/no issues going up or down
• Speedo and engine temp gauges are working just as they were before. Speedo correct +/- 2mph and coolant temp gauge correct. Coolant temp is ~195* as is should be (verified with infrared thermometer at radiator).
• Fluid level check shows level correct (vehicle running, up to temp, in Neutral, and on level surface)
• Back probed 3-pin connector leads near trans bell housing. Multimeter + lead on blue wire and - lead on orange wire w/white trace. While driving, PCM is commanding OD/TCC solenoid via grounding the orange wire w/white lead as evidenced by ~12v at cruise at speeds of ~40-45 mph
• Wired in a toggle switch with one lead on orange w/white trace wire and other to engine block. Toggling switch on in third gear above 45mph results in no change, re: vehicle does not shift into overdrive.

 

Might be a bad connection on the three pin connector..... If TCC and O/D are both out, I would suspect the power feed. It would be extremely rare for both solenoids to fail at the same time.

 

To be fair, I'm not 100% certain the TCC solenoid is out because I was under the assumption since I wasn't hitting OD then the TC wouldn't achieve lockup. At least no vehicle I've ever owned operates like that. I guess tomorrow I'll try checking voltage at the connector and then also trying the toggle switch on the TC side of the wiring to see if I can force it to lock in third gear.

I did try hitting the trick by hitting the brake slightly with my foot on the accelerator a few times and didn't hear the RPM change in third gear but it was also pretty loud driving around with the doghouse removed and would have been hard to distinguish a slight drop in RPMs that unlocking a converter would cause.

I will report back findings tomorrow. Time to get creative with some test wires...

 

There is some debate on that topic as well. On both my trucks, (one a 46RE, the other a 47RE.... essentially the same trans, just some heavier duty parts in the 47...) It will shift 1-2-3-TCC-O/D. If you hit the tow/haul button, it just disables O/D.

 

Update: So after further testing, the TCC is engaging via PCM command in third gear. Verified it by watching voltage on multimeter and closely listening to RPMs while in third. It is engaging...and also disengaging when applying brakes while foot still on accelerator. It's just difficult to distinguish by sound alone with all the noise with the doghouse off and going down the road. I also had the toggle switch hooked up on the TCC wiring side this time and was able to switch the TC lockup on and off a few times to get a feel for what it feels/sounds like. So @HeyYou , this appears to confirm what you stated about the 47 series trans shifting 1-2-3-TCC-OD. Seems the 46 is the same.

I also tested for voltage on center wire directly at the connector KO/EO and had voltage, so I'm going with a bad OD solenoid as diagnosis. New solenoid pack, fluid, and filter/gasket will be here Friday so I'll report back once I get it buttoned up and hopefully be able to report success.

 

Sounds like you have it dialed in. Definitely let us know the outcome.

 

Welp, unfortunately I got everything buttoned up with a new solenoid pack, adjusted rear band, and threw in a new 3-4 accumulator spring for good measure and still no overdrive. Womp, womp, womp...

Edit: Hooked up my pressure gauge to the OD port and go 0psi and nothing until overdrive was supposed to happen ~42-45mph and then pressure goes up to about 20psi. That doesn't seem right to me but I'm having a hard time confirming what pressures should be.

 

There is a 94 or 95 TRUCK service manual in the second gen ram FAQ/DIY section, (here.) Should be the same 46RH trans as your van uses. Hopefully, you can find what ya need in there.

 

@HeyYou Thanks so much for that. I wasn't aware of that resource and was relying on old tidbits and anecdotes from old forum posts.

Long story short, I'm just gonna huck a whole new trans/converter in the MF'er.

Reviewing the FSM and armed with the diagnostic info I have obtained so far, I was able to possibly narrow the issue down but not enough to conclusively figure out the issue short of pulling the valve body and/or OD unit. Numbers five and 14 of the "No 3-4 upshift" table from the FSM is about the only things that apply in my situation since I've narrowed out the others. Number five is a distinct possibility and number 14 hands it off to conducting a pressure test. However, the OD pressure test is assuming the 3-4 upshift actually occurs, so I don't think the pressure reading I obtained is of much worth. That leads me to believe the cause is within the valve body itself somewhere (re: stuck/worn components possibly with the 3-4 shift valve and/or timing valve, clogged orifice, etc). I thought about installing a new OD assembly, however that might be taking a step back and a waste of time/money. At this point, it wouldn't be worth the time or cost to pull everything apart and go deep-dive into the valve body and such. After all, it's a 30 year old transmission and might be best served with all new/updated components.

 

There is a snap ring that holds the o/d piston in place, against a humongous spring... it likes to break... and you get some interesting problems. But, I would also expect that you would find bits and pieces of it in the pan as well....

Full rebuild probably isn't a bad idea, given the age.... If you are feelin' froggy, there are videos on youtube that will walk you thru the entire process. Several members here have done so, having never been inside an auto trans before, all of them successful. Only tricky part is that spring. Need a press to remove/reinstall those parts.