4r100 went bang

mustube · May 19, 2014

It did this cool new trick today where it shifted 4-3-4-3 within about 2 seconds. Also seems like it feels like it shifts in the middle of second gear but then shifts hard into third about 200 rpm later. Kinda scared to even drive it sometimes.

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dsberman94 · May 19, 2014

Is this definitely diagnosed as something within the trans case and not something to do with chaffed wired in the harness?i understand parts are breaking but is there a chance it's getting mixed signals and doing things it isn't supposed to do due to a wire issue?

mustube · May 19, 2014

The truck didn't shift like this 3 weeks ago. I'd say except for the odd time that I had to hit the OD button to make it shift into third, it used to shift fine. Now 3rd is reliably hard and weird on part throttle. I will say that since I have gotten it back, I have not had to hit the OD button once to make it shift.

Are there any common chafe points for the tranny harness on these trucks? I need to find a tranny pressure gauge and monitor what it's doing, and figure out how to look at the pcm and see what's being commanded as far as line pressure.

dsberman94 · May 19, 2014

I'm really not sure. It was more of a question rather than a suggestion. We've got the 4r master, mark, in here.

mustube · Jul 15, 2014

I'm worried my truck is going to pop another shaft. I've noticed that when in 2nd gear it feels like it doesn't have any power and I can give it a bunch of pedal and it doesn't really go anywhere, and I think the tranny is slipping second gear. I have a friend who is going to scan it tomorrow for any possible transmission codes and reprogram the tire size to 35s (the biggest the abs computer will let you go to). I'm thinking that if it is slipping in second gear then the shift into 3rd (where it has broken both times already) puts a ton of shock load on the intermediate shaft. I'm going to work on getting a transmission line pressure gauge so I can monitor it while I'm driving. What range oil pressure gauge should I find? 0-250? I'm not real sure what line pressures normally run at.