TCU Speedo Wiring for 4x4

[502Burban]

I am installing a gray-box TCU into a 4WD Suburban with a 4L80e and NP205 transfer case.

It has an Autometer 5889 programmable speedometer.

What would be the proper way to wire up the speedo to the TCU?

Also, to ensure that the TCU is getting the proper vehicle speed when I have the transfer case in Lo range, should I possibly be reading the speed from the transfer case output (using a different sensor) instead of the standard TOSS location? Or is this not really important?

Thanks.

[TCITech1]

You defiantly want to get the speed setting from the transfer case. The red wire on the harness is the signal wire so just splice it into the existing TOSS wire and the black is the ground.

[502Burban]

Thanks for confirming my belief that I should get the signal from the t-case.

Not sure what you mean by splicing into the existing TOSS wire. Maybe I should have mentioned that this is a 1973 Suburban that I am installing a crate engine into.

I guess what I need to know is if you have a suggestion as to what I can use for generating a speed signal from the t-case, as I don't currently have a sender. I believe that Autometer has a sender that may work, but I'm not sure if it will, or of the wiring.

[TCITech1]

plug the TCU TOSS into to transfer case and then splice the wires from the Autometer piece into the TCU harness wires for the TOSS.

[502Burban]

Sounds good. I'll get the Autometer sender installed into the t-case and wire it into the harness as you suggest.

Thanks for your help.