I have a 2001 5.9 V8, 2 wheel drive with the classic 46RE 4 speed auto. Originally it no bus’d on me and required the ECM to be rebuilt and reprogrammed professionally. Then the transmission needed to be replaced, slipped like hell after leaking from the front pump all over the mechanics shop and threw a P0748 code some hundred miles after I drove it like that. It was pretty cooked. so I replaced it with the same transmission 46RE from 1997. On that tranny from 97’ I swapped the plug in’s for the sensors on the outside, swapped the valve body for a reman valve body for a 2001 46RE. The 97’ tranny has about 150K miles on it which is significantly less than the last. I compared sensor sizes, accommodated the newer valve body with a drain pan from 01 since it was significantly bigger, I cleaned the 8 pin sensor, grounded the transmission and basically swapped its entire brain for a reman one. Yet it’s still throwing P0748. Besides the code throwing it in in limp it shifts good. If I erase the code it shifts 1-2-3 smooth as butter but not 4th, and then the code pops up I’m at a total loss and need some help for this one.

 

Did your reman valve body come with sensors? If not, which sensors did you use? They changed in 99 or 2000..... and they are not interchangeable.

 

yes the reman valve body had all the wiring and sensors already attached. I saved the good sensors from my 2001 to use just to find out I didn't need to do that.

 

Are you getting 12 volts down to the trans? Should see it whenever engine is running.....

 

that’s something I have yet to check. I was thinking it has something to do with the 8 pin connector plug and the way it communicates to my computer. Aside from the electronics Is there any mechanical differences between a 46RE from 97 and a 46RE from 01?

 

Nope. The 2wd versions no longer had the VSS on the tailshaft, but, so far as I know, electronics were the ONLY difference on the 4x4's.