4r100 problem

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Nov 2, 2024 | 09:06 PM

Bill Owen

Thread Starter

Trailering

Joined: Mar 2009

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4r100 problem

Hi my name is Bill Owen, I am new to this forum and in search of solving My 4R100 trans problem. I recently rebult this trans and installed a Tugger kit. The problem is, is my truck(1999 7.3 F350 2wdr dually) starts out in 2nd gear, ever when I manually shift to first. The error code is P0781 1 2 shift error. Ive done almost everything. tried 2 different shift solenoid pack: changed all sensors: went through trans harness took apart and inspected the harness and plug ends: checked power and contentnuity from the pcm to the trans (all checked good); changed eccelerator pedal; went through the valve body and accumulator valve for stuck valves; and there is much more that Ive done to no avail. I just cant figure it out. Im about to pull it again and go through it to see if i can find what is wrong. The enitial reason for repair was burnt forward clutches in the forward drum, no first gear. Hopefully I can get some help here. Thanks

Nov 2, 2024 | 09:22 PM

Papa Tiger

Fleet Owner

Joined: Mar 2012

Posts: 26,073

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From: Near Cal. Avenue

Welcome Bill.

Check it out? 4R100 Transmission slow to engage 1st gear - Ford Truck Enthusiasts Forums

Nov 2, 2024 | 09:43 PM

Bill Owen

Thread Starter

Trailering

Joined: Mar 2009

Posts: 20

Likes: 7

thanks PaPa Tiger, Im not sure that applies to my situation. I dont have first gear it is not slow to start. I put gear shift in low and it takes off in second. there is no shift to second. The computor is commanding the shift but you dont feel a shift

Nov 2, 2024 | 10:14 PM

Papa Tiger

Fleet Owner

Joined: Mar 2012

Posts: 26,073

Likes: 4,145

From: Near Cal. Avenue

← most likely that is put together wrong or stuck.

Nov 3, 2024 | 07:07 AM

Bill Owen

Thread Starter

Trailering

Joined: Mar 2009

Posts: 20

Likes: 7

I had a trans shop check that and the accumulator valve out to see if Ive done anything wrong, He said everything looks fine and that it should work. But the trans still did the same thing. Today I plan on pressure checking the clutches; because i failed to do that after the rebuild. I will go over the valve body as well.