4wd input wiring???

[c5wagner]

16197427 PCM, 4L60E. How does the 4wd low input wiring work on the F8 pin for the PCM? Do you just have that wire grounded when in 4wd low? Supply power to it and remove it when in 4wd low? This is the last thing I need to figure out for the 16197427 PCM swap...

[brian617]

As far as I know the 4wd LOW input was only used on the 4L80e trucks because they use an input shaft speed sensor. Without the input it would cause gear ratio errors.

The 4L80e's used a three wire T-case switch while the 4L60e's used a two wire switch.

[c5wagner]

4l80e's have an input and output speed sensor on the unit itself so it wouldn't really need to filter 4wd low input for shifting....

[brian617]

The 4WD 4L80e uses the output shaft sensor in the T-case. So they need the 4wd low input to ignore the gear ratio difference created by gear reduction. The 4L60e doesnt.

[c5wagner]

The 4L60e doesnt.

You're saying this but I am experiencing otherwise, hence why I need to figure this out. Why else would the $0D bins have the option to filter 4wd low input if it didn't matter with the 4l60e? Why would there be a low range ratio option in the $0D if it didn't need it for the 4l60e? All I need to know is how the circuit works and I cannot find any proper wiring diagrams anywhere... I'm just going to try using my voltage ohm meter and test different theories I have with a low amp inline fuse and see if I cannot figure something out and put it here for anyone in the future.

[brian617]

Should be switched ground input.

What are you trying to accomplish with the input signal?

You'll have to buy a three wire T-case switch for an 4L80e equipped truck and add the extra wiring to the harness.

[brian617]

All I need to know is how the circuit works and I cannot find any proper wiring diagrams anywhere

Try looking for a k2500 wiring diagram, maybe in the $0E info on this site.