4l80E questions
 

I have an '03 GMC van with 6.0l and 4l80E for swap purposes. The van was a Dept. of Corrections van and they had been using it for parts. It has no gage panel so I can't tell what gear the tranny is indicating. That matters because the tranny is in limp mode (only 2nd and R) and I am trying to figure out why before I pull it. There is tranny fluid in the round connector and some sources say that could be the problem and others say not. The plug does have power to it with the key on. What should I be looking for? Replace the harness? If so where is the best source for replacement.

Re: 4l80E questions
 

You need to read the trouble codes. It sounds like an electrical problem and trans fluid in the connector is a problem.

Re: 4l80E questions
 

Only code it shows is a temp. sensor voltage, don't remember the number off the top of my head.

Re: 4l80E questions
 

Anyone else?

Re: 4l80E questions
 

Limp mode is 2nd and 3rd, but if you say it doesnt have power going to it when the key is on, then you need to figure that out since that's probably the problem. Check all the fuses.

Re: 4l80E questions
 

The plug does have power with the key on.

Re: 4l80E questions
 

Depends on what scanner your using. Most regular scanners will show regular DTC trouble codes (P codes). A Tech2/3 or reading via HPT Ecm scanner will show you the extended codes (T, U and BCM codes), and it will also show gears.

I'll have to check back through some of Clinebargers posts, he's the resident trans expert and has previously posted his preferred sources for trans harnesses.

Re: 4l80E questions
 

Thanks, will do.