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1996 4L80e: Have 2nd and reverse only no codes

Road Trip, I appreciate the reply. It was quite vexing, especially being a former professional technician. Luckily I kept my wits and remembered my diag training once I realized the symptoms and conditions were not permanent. The 2nd gear only was fairly straight forward, but the random loss of...
- RedVenom48
- Post #18
- Mar 2, 2024
- Forum: Transmissions
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1996 4L80e: Have 2nd and reverse only no codes

Zombie thread time! Well, since my last post I figured out what the hell was happening to my Burban. So, I lost overdrive and had HARD shifting 1-2 and 2-3. My best guess was something internal to the 4L80e. But after not driving it for a week I had to use it to take my waste oil to disposal...
- RedVenom48
- Post #15
- Mar 2, 2024
- Forum: Transmissions
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1996 4L80e: Have 2nd and reverse only no codes

@NickTransmissions I certainly did appreciate your pointers, they certainly helped! As for the transmission, I drove it in to work today and well.... unfortunately.... we have a failure. For an all too brief weekend, the solenoids had fixed this stubborn 4L80. Great and smooth shifts, couldn't...
- RedVenom48
- Post #13
- Dec 11, 2023
- Forum: Transmissions
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1996 4L80e: Have 2nd and reverse only no codes

Success!!! We have shifting! All 4 forward speeds and reverse!!! Looks like the little voice in my head that told me to replace the solenoids and pressure switches with the pan off was right. In total I replaced the following: 1 Input shaft speed sensor (genuine GM) 1 Internal trans harness...
- RedVenom48
- Post #11
- Dec 9, 2023
- Forum: Transmissions
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1996 4L80e: Have 2nd and reverse only no codes

Hi all. Little bit of an update regarding my issue. Im only just now getting around to diving into this (life, work, kids). Ok, so I verified my 10A fuse to the trans is good, Ive got source voltage at the trans connector pin when key on. I took a guess and decided to buy an internal trans...
- RedVenom48
- Post #9
- Dec 6, 2023
- Forum: Transmissions
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1996 4L80e: Have 2nd and reverse only no codes

Quick update: replaced the Input speed sensor with a Genuine GM sensor. No dice, still no gears but second and reverse. Though of note, there were metal particles on the old ISS I pulled out. My guess is Ill need a rebuild sooner rather than later. Ill have more time this Saturday to really get...
- RedVenom48
- Post #6
- Sep 19, 2023
- Forum: Transmissions
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1996 4L80e: Have 2nd and reverse only no codes

Ill have more time next weekend to dive into it. I checked the 10A Trans fuse in the drivers side dash fuse box. Intact and ok as the gauges died when i pulled the fuse and worked again once reinserted. Ill have to check for available voltage on the main plug itself. Current scan tool is just...
- RedVenom48
- Post #5
- Sep 18, 2023
- Forum: Transmissions
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1996 4L80e: Have 2nd and reverse only no codes

Hi, I have a new to me 96 GMC K2500 Suburban with the 454 and 4L80e 195k on the clock. Carfax shows a decent amount of service, including trans fluid service ~30k miles ago. Currently, the 4L80e is in limp mode with only 2nd gear and reverse. I have NO DTC codes stored, active or pending...
- RedVenom48
- Thread
- Sep 17, 2023
- Replies: 18
- Forum: Transmissions
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New K2500 Suburban owner here!

Recent lurker and new owner of a 1996 GMC K2500 454 Suburban. Thought Id stop by and say hi. I was originally trying to find a GMT800 8.1 K2500 but those were unicorns and if one popped up it was gone before I could make contact with the owner. Had a family event occur that reduced the available...
- RedVenom48
- Thread
- Sep 17, 2023
- Replies: 7
- Forum: Introduction