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47RE 1-2 shifts happening to quickly


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Regardless of throttle position my 1-2 shifts happen at 5 mph or less. Sometimes it will start in 2nd, drop to 1st, then immediately shift back to 2nd. I've adjusted the TV cable to no effect. Manually shifting the trans results in perfect operation. The trans was rebuilt by a local shop who screwed me over pretty good so I'm not exactly sure what's actually been done to it. The VB should have a DTT shift kit still in it, which I had installed about a year before the rebuild. My 1-2 shifts have always been the way I described, even before the shift kit and remained the same after the rebuild. During the build all of the electronics in the VB were supposed to be replaced but I have a strong suspicion they weren't. After some research it seems a faulty pressure transducer may be the cause. Does it sound like I'm on the right track? 

 

I'm a mechanic by trade but I've never rebuilt an automatic transmission and honestly wasn't that familiar with their operation. I've been doing all I can to learn how they function by watching videos and digesting as much literature as possible.

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Well I found the cause of the 1-2 shift issue, it was the 100 ohm resistor that is sometimes used to keep the trans from going in to limp mode after line pressure is increased. Seems the truck was never tested to see if it actually needed the resistor, which it didn't. With it removed I was able to adjust the shift points via the TV cable. Now 1-2 shifts happen around 17 mph and 2-3 shifts around 30 mph or so. 3-4 is around 40 mph and lockup around 48 mph since wiring in a pot to replace the TPS

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