VSS issue in 6.0 swap in 94 4x4

[slow94]

The way vss is setup in 94, is the twisted pair wires from the vss going straight into that drac box, then the decoded speed signal is fed to the guages, tbi pcm, abs, and cruise. So when you hooked up the old tbi vss wires, you were feeding the guage, but your lq4 pcm did not have a clue how fast you were going causing the weird/no shift.

On the lq4, the vss sensors go straight into the pcm, the pcm decodes the signal based on tire size, gears, etc and then feeds a speed signal to the guages, cruise, abs, etc.

So now that youve hooked up the nelson harness to the transfer case, youre giving the pcm the correct signal it needs to shift, but you've taken the 94 drac box out of the loop by unhooking it. That is where splicing into the blue wire comes in, your bypassing the 94 vss/drac setup and using the speed output from the pcm. Hope that makes sense.

To get the proper ground to the pcm for 4wd low, you can build a simple relay circuit to apply ground when your 1994 transfer case applies 12v.

[HPICamaroSS]

The way vss is setup in 94, is the twisted pair wires from the vss going straight into that drac box, then the decoded speed signal is fed to the guages, tbi pcm, abs, and cruise. So when you hooked up the old tbi vss wires, you were feeding the guage, but your lq4 pcm did not have a clue how fast you were going causing the weird/no shift.

On the lq4, the vss sensors go straight into the pcm, the pcm decodes the signal based on tire size, gears, etc and then feeds a speed signal to the guages, cruise, abs, etc.

So now that youve hooked up the nelson harness to the transfer case, youre giving the pcm the correct signal it needs to shift, but you've taken the 94 drac box out of the loop by unhooking it. That is where splicing into the blue wire comes in, your bypassing the 94 vss/drac setup and using the speed output from the pcm. Hope that makes sense.

To get the proper ground to the pcm for 4wd low, you can build a simple relay circuit to apply ground when your 1994 transfer case applies 12v.

I did splice into the blue wire. Was that the wrong one in my picture? I spliced into the solid blue. Do I need to splice into the lt blue striped one?

[slow94]

yes, the light blue wire goes to the speedometer, the dark blue feeds something else

[HPICamaroSS]

yes, the light blue wire goes to the speedometer, the dark blue feeds something else

When I splice into the light blue wire, do i keep it still connected to the buffer box ( like i did with the dark blue wire in the previous pic), or do i cut it so its not connected to the box. Thanks!

[slow94]

I clipped the wire from the box, and it works fine

[HPICamaroSS]

I clipped the wire from the box, and it works fine

Is there a need to hook the solid dark blue wire back up to the box. ( the one that i tapped into the first time)

[slow94]

I believe that dark blue wire went back to the tbi pcm, if you removed the tbi pcm, id just cap that one off