Transmission issues... hope someone can help

[FrankieRider2]

I have a 2001 Dodge Ram 2500 4 X4 with the Cummins Diesel and 47RE automatic transmission. I had the transmission rebuilt 30,000 miles ago in 12/2015 and it has been flawless up until the past month.

I've been having an issue where the electronic overdrive drops out and the Trans Temp light and OD Off lights come on while you're driving. Sometimes it's a one time deal, and sometimes it's all you can do to get the truck to drive like it's supposed to. Right now, about 90% of the time it drives like it's supposed to.

I've taken it back twice to the shop that did the work and they pulled the pan twice, replaced the solenoids and all the internals twice. I had a new external wiring repair harness put on it for the external part and still the problem is persisting. Has anyone had experience with this or if anyone has advice it would be greatly appreciated. My truck has always been bulletproof and super dependable, and this is about to drive me bonkers. Thank you.

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[dudeman2009]

Do you have an external trans cooler? How big it is?

 

[FrankieRider2]

Do you have an external trans cooler? How big it is?

The truck has the OEM cooler behind the bumper, no damage to it. But several times the truck has done this immediately after startup in the AM...and there's no way the Trans Temp whould be high when the truck's been sitting all night....

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[2001Ram1500SL]

try using a bigger trans cooler the stock coolers are good for there times also you could check sensors and ask about your overdrive unit and don't drive with it when not needed

 

[dudeman2009]

If the trans temp goes up too high it will automatically drop out of OD. For the time being, unless proven otherwise, the OD light is reactionary. For some reason the PCM things the trans temp is too high.

If they've replaced the trans temp sensor, did they use a Mopar replacement or a cheap one from autozone or O'reillys? I only ask because these trucks hate some non OE parts, namely TPSs and IACs.

 

[Max78]

My brother in law had a 01 cummins that would drop out of OD occasionally, no lights or over heating. It got progressively worse as time went on. It finally got so bad it would only lock up for a second or 2 and then unlock.

We found that these trucks have crappy grounds, and the transmission wiring it susceptible to noise. We added a couple of additional grounds from the engine to body to battery. What fixed it for good is when we wrapped the wire harness that goes under the alternator with tinfoil, yes tinfoil.

After we did that it drove like a new truck, never had another transmission issue.

Im not sure in which order you issues occur, but if your TQ never locks up at higher speeds it will heat the trans up pretty quick.

 

[jlbayes]

The first step should be confirming the transmission is actually heating up with an external transmission temp. gauge. Not throwing parts at it.

 

[dudeman2009]

The first step should be confirming the transmission is actually heating up with an external transmission temp. gauge. Not throwing parts at it.

This.


It's easy to make assumptions and start moving on parts before having the whole picture. Even the best make that mistake, and we are far from the best.

 

[nc bogger]

I had the same issue a few years ago. I had a short where two wires pulled out of the trans connector just enough to touch each other. Theres a service bulletin on the od control solenoid which also has the temp sensor integrated into it. After the wires touched, it shorted my od solenoid and was an intermittent issue. $130 and two hours later I had it fixed. Theres also a bulletin on the pressure switch (cant remember what the actual name of it is) in the trans so those need to be changed and most shops dont check service bulletins when they rebuild anything unless theyre good. Hope that helps.