just had the tranny rebuilt about 3k ago. it been running like a champ until this weekend... maybe. its on a 5.9 magnum but when it was built we built it to all the cummins specs like bigger planetary's and more clutches blah blah. also added a bigger cooler and different pan to help it out a bit as i do a lot of towing. this weekend i was hauling my camper around up through the mountains and the trans started to get warm. i noticed that at about 142deg the over drive light would come on and i wouldn't have overdrive but then as soon as it went down to about 138 id have it back again. it happened to me 3 times this weekend. but then other times when i thought the light should come on it didn't but thinking back on it now i wasn't using overdrive being that i was climbing some steep hills. any thoughts

 

I wonder if the trans itself has enough cooling capacity, regardless of the upgraded parts, to tow in overdrive...... Where are you checking trans temp at?

 

im checking the temp at the bottom of the pan with a probe to my gauge

 

If you are doing towing you should put a temp sensor in the exiting cooler line. This will be more representative of how hot your trans really is.

o/d is not malfunctioning. When the trans overheats it disables o/d. You need to verify trans temp with a scan tool. If it is not overheating (I think 230 max, not sure), and the computer is disabling o/d when the trans is NOT in fact over heating you may have an electrical issue with the temp circuit.

But if you are in fact over heating you need to find the problem and resolve that. BTW how big a load are you towing?

 

http://dieselmanor.com/dm_products/FTG-MFD.asp

 

If you were driving with od off then the light should have been on constantly. If it was coming on then going off you were either in od or you could have an electrical issue maybe with the od switch.

 

You are suppose to turn off OD when towing anyway, period. Even the owners manual says so. As a matter of fact, the owners manual says to turn it off going up hills even if you are not towing. And I don't think upgrading parts will matter.

 

i know im not supose to tow in overdrive but id rather that then have my truck sit at 3 grand for 9 hrs. the load wasnt sustantial its a 9ft truck camper with our gear in it it. my heaviest weekend id say would be about 5500lbs. im definatly looking into the cooler line fitting that seems like a much better way to go

 

That or a tranny rebuild? And I only said turn it off going up inclines.

 

will the 46re drop od on high temp as well? my 98 1500 4x4 5.9 rebuilt less than 30 k serviced about 10k had this happen yesterday as well. i'm not towing or hauling anything its just hot as hell right now in oklahoma 102-108 degrees days and i just replaced the ac compressor so may be i'm convecting additional heat load into the trans cooler. the trans didnt seem to shift in the other gears properly either though. and under normal temps it shifts abnormaly while in od temperary bumps unless i lock in tcc clutch with a manual switch i have. it doesnt always do this just 10-20% of the time.