96 K2500, New motorized front differential actuator

[Karl Stevens]

I posted previously about my 4WD fuse blowing. I determined that the thermal front differential actuator was bad. I've installed the upgraded motorized actuator (600-601). My problem now is that I cannot locate the C120 connector near the transmission to splice in the additional brown wire on the adapter wiring harness.

Can anyone please tell me how to locate the C120 connector? I cannot see anything from below or above that appears to be correct. The only connector that is even accessible is one that goes to an O2 sensor on the left side exhaust. I found a diagram online, but it appears the connector is above the transmission, but even the diagram did not help me. I would appreciate any help from anyone who has made this upgrade.

Thanks so much.

 

[Karl Stevens]

Well, no one ever responded, so maybe this isn't a big issue for others, but I thought I'd follow up in case anyone else has similar issues.

Regarding the location for splicing in the brown wire on the new wiring harness, I found it impossible to splice in at the location indicated in the instructions, so I followed the wire further back toward the transfer case switch and spliced in where I could get both hands on the wire. I worked.

As far as the new actuator, it requires two hots and a ground (thus the new wiring harness). One hot comes from the OEM power source to the heat-activated actuator. The problem is that the connector on the new harness doesn't fit the OEM connector, so I had to snip the new connector and splice in the OEM connector. You have to make sure you have the hot and ground correct, but it's difficult because the OEM is two black wires and the new has black and blue. Get them backwards, and nothing works.

After getting it wired up, I left the actuator out while hitting the 4WD button. I could see it extending and retracting, so I knew it was working.

I hope this helps others in the same situation.

 

[Karl Stevens]

I have a follow up to my previous posts. The instructions for running the second hot wire from the transfer case to the actuator say to have the wire go over the top of the transmission. This is a big mistake. There is so much heat from the transmission and the exhaust that the protective sleeve on the wire melted and caused the wire to short out. I had to cut out the burned section and reroute a new splice under the tranny, across to the right side, avoiding any hot surfaces.

This replacement actuator works well, but the instructions for installing the new wiring harness are inadequate. They state to connect the second hot wire in an impossible location, and to run that wire over hot surfaces. Bad communication and bad advice.

 

[Mastermech]

Wiring

If you supply me with your email address, I'll send you the GM instructions (unless you already have them). Mech