I'm a long time reader but first time poster here and have a bit of a head scratcher. Vehicle is a 2000 Dodge Dakota 3.9l 4X4 with about 170k that I've owned for over 6 years. The 42RE trans has never been great in it and was getting worse and worse so I bought a rebuilt 42RE & new torque convertor to swap out. The swap went fine, albeit long in the garage on jack stands by myself. After tweaking the TV cable the truck ran fine for several days and then one morning it threw a check engine light. After the key on off steps it displays P0743 and seemed to be in a limp home mode as it only appeared to have 2nd gear. So I did what any sensible person might and disconnected the battery turned the ignition on for 15 seconds then back off and reconnected the negative terminal to clear the code and see if it came back. Drove it around to several places that day and it drove perfectly fine. Next morning the light is back on and same error. Knowing the 8 pin connector on these trans are prone to get sketchy and short out I disconnected the battery, got under the truck, inspected it and was please to see only 1 wire was starting to show copper. I cleaned everything well and coated the base of the 8 wires with liquid electrical tape for some extra security and after it dried wrapped the harness in electrical and cloth loom tape. Reconnected the battery and she fired up and drove around town that day again with multiple instances of turning off and on at stores. Yesterday morning I started it up and threw the same code again. Pulled the battery cable again, got under there and proceeded to ohm out the 5 of 8 wires in the harness back to the PCM and all 5 of those ohm'd out well <.46ohm. So I put leads coming out the back of the 5 pins on the C2 harness reconnected the battery and the truck started up fine with no code. After letting it warm up some I checked all 5 wires but specifically the TCC solenoid wire to see if it was grounding or dead shorted and it came up clean. Turned it off, pulled the leads from C2 and put the back of the connector on it and went on my way running errands. Like before I went to several places and cycled the engine a couple times. Also like before it ran and drove good with no codes. Now this morning I hopped in and started it up and sure enough that dang code is back and it like it's in 2nd gear.


I'm kinda stumped why it can drive all over one day and sitting overnight now three times in a row causes it to throw the code. It drives bad of course with the code thrown but clear it and it drives fine again the rest of the day. That doesn't necessarily sounds like bad solenoids or it would crop up again right away or quickly. I've ordered a new pair of TCC/Shift solenoids I'm gonna try next. Has anyone seen this behavior before or have any suggestions on testing other components? Are those solenoids constant duty controlled, PWM or voltage based to where they can be monitored with a meter or a scope? I'm gonna try putting my cheapy ELM OBDII scanner on it tonight and see if anything else comes up and if that doesn't work I'm pretty sure I've got a license left for my HPTuners OBDII plug as well and I may see what it can tell me.


Thanks in advance for any insight.

Steve

 

That's an intermittent failure..... Since you recently installed a rebuilt trans, I would suspect the TCC solenoid itself as the potential problem. Any warranty on the rebuild?

 

Thanks for the quick reply, there is a year warranty, I'm trying to exhaust potential "easy" fixes before resigning myself to 6 hours under the truck by myself pulling it. The warranty is a swap for another unit and the company is ~4 hours away hence why I'm trying the easier stuff. Replacing the solenoids doesn't look to crazy hard and my local O'Reilly's had a new one for $70. I see there are two approaches to replacing it (drop the whole lower housing or remove the accumulator housing to get at the case connector). I think I'll try it on my old unit and see which is easier if done upside down.

Were there any differences in the years for compatibility with the solenoids? I was told that the replacement rebuild unit was a 2000 like mine but I've see a number of references to replacement solenoids being 96-99 and 00-04. So it makes me wonder if the unit was not a 2000 or really how well it was rebuilt.

 

I suspect if you open up the trans, it will void your warranty.... I might be tempted to talk to the company first, and see what they suggest/are willing to do.

Yeah, swapping transmissions by yourself really isn't any fun.

 

definitely a thermal issue.

What if you drive it in the morning, let it sit all day, then drive it in the evening?

After reset, the code is in 'Pending' but then gets cleared when it starts getting warm.

Once the trans cools down, connection breaks, sets code at start.

I'm going to say it's a sensor issue. It might be at the case interconnect, but $0.02 says it's at the solenoid pack.

 

So I replaced the solenoid pack & of course the case harness last night. Filled it back up and did a quick test drive with everything feeling good. This morning I started it up just to see if it was throwing the code again and was happy to see it wasn't. I put a new solenoid pack in but still have the one from my original trans that was replaced as well as this "defective" one so I plan on doing a little post-op on it comparing it to the old one checking resistance etc. On a side note I am pretty sure I figured out why my old/original trans was acting horribly. I've been using it as a guinea pig to see how hard it would be to replace the solenoids and look over the valve body. I wasn't to far into that trans and found the accumulator spring snapped in 2. Luckily no scarring or damage to the piston or bore so I'm gonna slap a new filter and spring on it, plug all the holes well and bag it for storage incase this trans ever craps out. To be honest this seems like it might be an eventual scenario as this "fully rebuilt with a master rebuild kit" unit more appears to be a fix the broken part, paint it silver and throw in a new torque convertor and call it fully professionally rebuilt. The solenoid packs, aside from being bad, based on the faded wire colors looked factory and same goes for the governor sensor / solenoid. I also feel the gaskets were not touched as the gasket between the accumulator housing and the lower housing looked like it was there for awhile.

I would have preferred what I paid for as a fully rebuilt unit but this is not my daily and is more of a landscape / Lowes / Hunting truck so it won't see lots of abuse. So I'm hoping it should last a good long time.