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Author Topic: 4L80E Automatic Transmission Expert  (Read 1734 times)

Screaming Bear

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  • Posts: 1991
  • Location: Dayton, Nv
  • "the Bear Whisperer"
4L80E Automatic Transmission Expert
« on: November 13, 2013, 02:20:21 PM »

I am trying to prevent second gear downshift with a shift hold switch. I got my nerve up and tapped into the PCM wiring on my motor home for the B shift solenoid. It didn't screech to a stop and send me through the windshield. Good. It did stay in 3rd when I flipped the added switch and floored it. Great! The check engine light did not come on and I really got my hopes up at that point. However it does go into limp mode requiring a power off to reset 1st, 4th and lock-up. Bummer. The TCC is a modulated signal and there is a line pressure solenoid to soften the shifts as well. I can't do all that. I must prevent limp mode with a chip reprogram to ignore the missed command result for 2nd. Any ideas? 
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51 CJ3-A, 4.3 TBI Chevy, SM420, Dana 18TC, 30/44 Full Floaters, Yukon Front Axle and Hubs, rear drive flanges, Detroit Fr / E-Locker Rr, 4.27:1 Gears, 74:1, HD steering / 4 wheel disk brakes, Viair 550C, 100% LED - VisionX headlights, Rigid Light-bar, DOT Fogs, Grote tail, Soft Top and Heater, 35"KM-2's, 3" up, no articulation - it works

Mr.B

  • "But officer, it was a Subaru!"
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  • Location: Roseville, Ca.
Re: 4L80E Automatic Transmission Expert
« Reply #1 on: November 13, 2013, 05:24:16 PM »

Don't they have a Crazy/retired/RV'r/with too much time on his hands, forum out there? :biggrin:
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White '94 YJ 2.5L 5 speed, 35" BFGs KM2's, 5" lift, Mark VII 2 speed fan, Milemarker PE8000, Front Aussie Locker, Power steering conversion, '98 Cavalier seats, MORE Boomerangs in front, 136 amp ZJ alternator, JB conversions SYE, Tom Woods custom drive shaft, 8.8 with ARB, 4.88 gear ratio, Teralow

You're a super genius....
The difference between stupidity and genius is that genius has its limits. -Albert Einstein

Screaming Bear

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  • Posts: 1991
  • Location: Dayton, Nv
  • "the Bear Whisperer"
Re: 4L80E Automatic Transmission Expert
« Reply #2 on: November 13, 2013, 07:56:52 PM »

Don't they have a Crazy/retired/RV'r/with too much time on his hands, forum out there? :biggrin:
I found a guy on YouTube that runs this trans with switches and no computer at all. He could be crazy, but I think he is a genius. The 4L80E would be one tough 4spd auto in a Jeep. (relevant to this forum)

I was hoping someone could explain how important the TCC signal being modulated is, and also if shifting under full line pressure will cause any problems other than firm shifts.
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51 CJ3-A, 4.3 TBI Chevy, SM420, Dana 18TC, 30/44 Full Floaters, Yukon Front Axle and Hubs, rear drive flanges, Detroit Fr / E-Locker Rr, 4.27:1 Gears, 74:1, HD steering / 4 wheel disk brakes, Viair 550C, 100% LED - VisionX headlights, Rigid Light-bar, DOT Fogs, Grote tail, Soft Top and Heater, 35"KM-2's, 3" up, no articulation - it works

Mr.B

  • "But officer, it was a Subaru!"
  • Administrator
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  • Posts: 5109
  • Location: Roseville, Ca.
Re: 4L80E Automatic Transmission Expert
« Reply #3 on: November 13, 2013, 08:15:40 PM »

You got a link to the crazy/genius guy?
Logged
White '94 YJ 2.5L 5 speed, 35" BFGs KM2's, 5" lift, Mark VII 2 speed fan, Milemarker PE8000, Front Aussie Locker, Power steering conversion, '98 Cavalier seats, MORE Boomerangs in front, 136 amp ZJ alternator, JB conversions SYE, Tom Woods custom drive shaft, 8.8 with ARB, 4.88 gear ratio, Teralow

You're a super genius....
The difference between stupidity and genius is that genius has its limits. -Albert Einstein

Screaming Bear

  • Supporting Member
  • Offline Offline
  • Posts: 1991
  • Location: Dayton, Nv
  • "the Bear Whisperer"
Re: 4L80E Automatic Transmission Expert
« Reply #4 on: November 13, 2013, 09:31:33 PM »

You got a link to the crazy/genius guy?
Try this, I promise to do this with a bit more class. 4l80e full manual with no computer
Logged
51 CJ3-A, 4.3 TBI Chevy, SM420, Dana 18TC, 30/44 Full Floaters, Yukon Front Axle and Hubs, rear drive flanges, Detroit Fr / E-Locker Rr, 4.27:1 Gears, 74:1, HD steering / 4 wheel disk brakes, Viair 550C, 100% LED - VisionX headlights, Rigid Light-bar, DOT Fogs, Grote tail, Soft Top and Heater, 35"KM-2's, 3" up, no articulation - it works

Mr.B

  • "But officer, it was a Subaru!"
  • Administrator
  • Offline Offline
  • Posts: 5109
  • Location: Roseville, Ca.
Re: 4L80E Automatic Transmission Expert
« Reply #5 on: November 13, 2013, 10:03:52 PM »

He must be a genius, I didn't understand a thing he was talking about. I love the dashboard, and custom shifter.
Logged
White '94 YJ 2.5L 5 speed, 35" BFGs KM2's, 5" lift, Mark VII 2 speed fan, Milemarker PE8000, Front Aussie Locker, Power steering conversion, '98 Cavalier seats, MORE Boomerangs in front, 136 amp ZJ alternator, JB conversions SYE, Tom Woods custom drive shaft, 8.8 with ARB, 4.88 gear ratio, Teralow

You're a super genius....
The difference between stupidity and genius is that genius has its limits. -Albert Einstein