Hi all, I just bought a 2000 Ram van 2500 with a 5.9 to use for various hauling duties. It runs great but I noticed it would not shift into overdrive and i had a CEL so I pulled the codes and got several that are related to trans functions:

443 evap purge solenoid
753 trans 3/4 shift solenoid
1740 Tcc or O/D solenoid perf
1765 trans 12 volt supply relay ctrl

Surely these are all related but where should I start? Doesn't seem to be slipping or shifting weird, just no overdrive. Any help would be greatly appreciated, you guys seem to really know your stuff from what I've read on here so far.

 

It means that the overdrive solenoid (or wiring to it) has failed. The overdrive solenoid is pretty easy to replace but I'd double check the wiring harness and connectors first.

 

I had the 1740 code. Changed the part but the final fix was rebuilt tranny from Jasper. Only had 165,000 miles. Now about 176,000 and van runs great with no tranny worries.

 

Ok, I bought a kit that had the overdrive solenoid, transducer, speed sensor, new accumulator spring, plus a few other parts. While I had it open I found the accumulator spring broken, the intermediate band anchor laying in the pan, (broken), and both bands really loose. So after fixing all that, it still would not shift into overdrive!!! I finally figured out that the PCM was not sending a ground signal to the transmission relay to energize it, and all I was getting was 2nd and 3rd gear. For a test I ran a separate ground wire to the relay. Now the relay is energized when the ignition is on, and it runs and shifts fine in all gears. My question is, Can I leave it this way or is there any time during normal running operation that the PCM would need to drop out the relay? If so, I'll have to get a new PCM but if it doesn't hurt to leave it like this then I won't worry about it.

 

Ok, just so I understand: you grounded the brown wire going to the connector at the transmission ?

 

No, I grounded the #2 terminal of the transmission relay located in the relay box by the battery. That terminal receives a ground signal from the PCM off of pin #30, I believe. I'm just not sure if it is energized anytime the ignition is on, or if there are instances during running when the PCM needs to drop the relay.

 

Oh ok. I have the schematic in front of me and looks like thats needed for all three transmission solenoids to operate. I can't imagine why the PCM would need to cut power to all transmisson solenoids during normal operation.

I think the PCM is still controlling all transmission solenoids so I don't see an issue as long as this bypass isn't generating any trouble codes.

 

Great info, thanks!