VSS issue in 6.0 swap in 94 4x4

[slow94]

All of this is assuming your still running the 94 ifs and np241 that came in the 94 originally

[Mickeymotormount]

Looks like mine on my '93. The tailshaft sensor is the VSS that goes to the PCM. As depicted above, that sensor shown goes to the floor shift lever.

I left everything original except for hooking up the 4wd Low wire from the PCM. That is something that needs to be done. Since the drivetrain will be spinning at a much slower RPM compared to engine speed in the 4 Low position, the 4 low wire from the PCM must be grounded so the PCM "knows" the drivetrain is in 4 low and shifts the trans accordingly. I mistakenly removed that from my modified original harness and now must repin the PCM and find how I can get the wire grounded in the 4 Low position. It will take some doing but I figured I'd mention it so someone else doesn't make the same mistake I did.

[HPICamaroSS]

Looks like mine on my '93. The tailshaft sensor is the VSS that goes to the PCM. As depicted above, that sensor shown goes to the floor shift lever.

I left everything original except for hooking up the 4wd Low wire from the PCM. That is something that needs to be done. Since the drivetrain will be spinning at a much slower RPM compared to engine speed in the 4 Low position, the 4 low wire from the PCM must be grounded so the PCM "knows" the drivetrain is in 4 low and shifts the trans accordingly. I mistakenly removed that from my modified original harness and now must repin the PCM and find how I can get the wire grounded in the 4 Low position. It will take some doing but I figured I'd mention it so someone else doesn't make the same mistake I did.

Thats really good info. I was having the same problem. Is there any wire specifics you can give me. Routing/ Splicing into what wire? Color of wires? Thanks!

[HPICamaroSS]

AND since my 94 tcase has a different style vss connector compared to nelsons new style vss pigtail, is that all you do is cut off their pigtail and put the old OBS connector on their harness so it plugs into the tcase? Does it matter what way the wires go?

[Mickeymotormount]

Thats really good info. I was having the same problem. Is there any wire specifics you can give me. Routing/ Splicing into what wire? Color of wires? Thanks!

Here's the schematics and a description of the operation of the transfer case for a '99 Silverado with the 6.0.. Following years may be the same or different. The 4 wheel drive wire is gray/black and is pinned at the red C-2 connector at location 16. From '03 on, it's the green connector(C-2) and the same gray/black wire at pin #16.









Still reviewing my '93 schematics to find out how I can ground this wire when I switch into 4 low. Stay tuned, I may be close to an answer.

[HPICamaroSS]

All of this is assuming your still running the 94 ifs and np241 that came in the 94 originally

Correct. 94. IFS. But I switched to a 94 2500 tcase so the splines would match up with my 4l80