4L80E NO REVERSE EASY FIX?

[pholliday1]

1991 crew cab all forward gears work, no reverse just wondering if this sounds like a broken band or not? Reverse is kinda handy once you get used to it. Lol

[Irish_Alley]

two problems with the 4l80e one could be line pressure, the other the 80e has a fail safe that wont let the trans shift to reverse if it senses a speed of greater than 8mph. i would first unplug the main plug for the trans, it can leak fuild into the plug and short the pins and cause all sorts of problems. if you see no fluid try to drive it with the plug unplugged in reverse. this will eliminate the tcu controlling the trans it should override the fail safe if thats the problem.

if thats no the problem see what your line pressure while in Reverse, 3rd gear, 4th gear and in manual 1st. encase you also didnt know the reverse band is also used for engine braking in manual 1st gear

[pholliday1]

Thanks ! actually the more you can tell me about this trans the better.

[Engineer]

Like Irish said, the low/reverse band is applied in manual low. Try putting the shifter in manual low then drive forward to about 5mph. Let off the gas pedal to see if the transmission feels like it is attempting to hold you back. If so you can possibly eliminate the idea that the band has a mechanical failure.

The other clutch that engages during reverse is the direct clutch. Since you said the direct, or 3rd forward gear works we can assume there is nothing wrong with the direct clutch.

I would focus on the low/reverse band and its control mechanism.

[pholliday1]

Copy that! Thanks for the info due to scheduling it will b a solid week before I can get to truck ill report back

[Irish_Alley]

the leaky connection is a common problem

[pholliday1]

So truck arrived late last night. Only got a chance to drive it in first gear, which it didn't shift out of first so it looks like the band may be fine. A quick glance with the flashlight revealed a transmission soaked electrical plug. Tonight's first order of business when I get home is to unplug the tranny and test it. I will report back!

[Irish_Alley]

Here's the part number if it is the problem.

think i found it 24241218

now i have to make sure the other connections are ok

[pholliday1]

Transmission plug is saturated with transmission fluid inside and out. I found three separate electrical connections on the trans I unhooked all three still no reverse ((     I promptly broke one of the plastic keeper pieces for the speed sensor I'll have to try and source a replacement somewhere. The plugs are very brittle as the truck has 286K on it!