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check engine light from torque convertor

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I have a 2005 ram 3500 4x4 with an after market torque convertor (all billet triple clutch) that performes perfect, but every time i use tow/haul mode the check engine light comes on. The code reads (torque convertor overdrive siliniod performance). The light comes on at about 35 to 40 miles per hour and normally as it down shifts from third gear to second gear. Has anyone else heard of this?
 
The code is P1740 and it means the torque converter is not locking up. Each time the trans shifts to 3rd gear lock up the ECM looks for the RPM to drop when the controller commands lock up. If the RPM does not drop the controller makes an assumption that there is a converter (or control) problem. You mention in tow/haul it does it. If you also have an aftermarket controller that inhibits lock up in tow/haul that could be the reason for the light. Are you sure the converter locks in tow/haul?
 
The code is p1740. I do not have an aftermarket controler. I have an edge chip that will display lockup on it and i can also feel the lockup, so i am sure that lock up is working. I can drive a 1000 miles with no light, but in tow/haul mode the light will come on within 20-30 miles.
 
I got the same code last week. I upgraded my t/c and v/b. Came on about two weeks after install while I was normal driving. I took the truck back to the diesel performance installer after 1,000 miles for recheck. He told me this is normal code for some 05's. Like the post above. It's due to the rpm drop that your truck senses. He looked over my transmission and everything ok. He cleared the code and nothing so far. As long as you feel no drop off on your trucks performance. Don't worry about it and clear the code.
 
I've gotten that code several times using tow/haul mode around town and I haven't modified my transmission. The way I understand the operation of the transmission for this code, is the software is looking for at least 50 rpm reduction when the torque converter is being locked. I got most of my error codes while driving around town and sometimes there isn't that much difference between the torque converter speed before and after lock up when going slow and light acceleration. Since you put in a new torque converter, hopefully that is more efficient than the stock unit, there may not ever be much separation of rpm unless you're really stopping on the pedal. I took my truck to the dealer about it and he told me to ignore it, which I have without any problems.
 
That's what I am doing since it came back on today again. Do you know if so many cold starts will reset the code?



IIRC, after 10 restarts it will reset if the error condition has not reappeared. If it come sback then it stays on.



As long as it doesn't set the transmission into limp mode just drive it. Dave Goerend supposedly has figured out a way to mitigate these problems with VB and TC upgrades but not sure if it applies to yours. Might give him a call and se what he has found. :)
 
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