If you find your 4L80E transmission is stuck in limp mode, it’s a great idea to check where the fuse is located. It’s pretty easy to do. So without further ado, here’s how to locate a 4L80E fuse.
Locating the 4L80E Fuse
- The 4L80E fuse is located in the engine bay. You’re going to look for a giant fuse box. It’s covered in plastic and usually pretty close to the battery. On the Silverado, Tahoe, Sierra, Express etc, it’s located on the driver’s side above the fender.
- Once you’ve located the fuse box, you’re going to be looking for a fuse called TCMB. That stands for transmission control module, which is what controls the transmission. When this fuse is blown the transmission automatically defaults to limp mode.
- Once you’ve located the 4L80E fuse location, you’re going to want to test it. There are two ways of going about testing the 4L80E fuse. The first method is pop out and inspect. Make sure that you don’t have the key turned on for this. The other option is to grab a test light and make sure that the fuse is hot on both sides. This method is superior in that it doesn’t involve pulling the fuse, and you can see it it’s hot on both sides. Sometimes a fuse will look fine but still not work. If you are absolutely convinced your fuse is blown, and you don’t have a test light, it would be worth your time to swap it anyway.
Symptoms of a Blown 4L80E Fuse
Whenever a 4L80E has blown its fuse, it can no longer get instruction from the TCM. So, when you put it in drive it’ll only run in third gear. You may manually shift it into second for taking off. It’s still not good for the torque converter though. It takes a lot of extra slipping to take off in 2nd or 3rd.
If your turned out to be fine, but the transmission is stuck in limp mode, it’s either going to be a harness issue, or a bad solenoid. These transmissions are famous for having a bad connection where the harness plugs in. Go ahead and take a look to make sure that nothing is wrong and the contacts aren’t corroded.
Conclusion: 4L80E Fuse Location
Good luck fixing your 4L80E. If it keeps blowing the fuse after you replace it, check under the truck for a frayed wiring harness. If there is anything I could add or remove, please comment and let me know.