Help Needed - Rear Speed Sensor Wiring Leads to Nowhere. w/ PICS

[LoCascio_Inc]

1998 K2500 ECSB has had a code C0236 (missing rear speed sensor) since purchased.

I disassembled the wiring harness to look for a short and revealed that the wires from the rear speed sensor on the transfer case output terminated at another connector with a female to female adapter about 18" down the harness.

Connector A was plugged into the rear speed sensor. Connector B was bundled to the rest of the harness (appeared factory). I'd always assumed it was for a PTO or some option my truck never came with.

I'm confused about where to go from here. No other unplugged connectors appear to be anywhere in the area.

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[LoCascio_Inc]

Turns out this harness extension/adapter is to extend the connector for the rear VSS in 4x4 applications from the output sensor on the 4L80E transmission to the output sensor of the transfer case. I unplugged the harness from the transmission's output sensor and plugged it into connector B on the extension. Now the output sensor on the transfer case should be applying rear VSS signal as intended, but I'm still getting a C0236 (missing rear speed sensor). I think I have a short somewhere...

Does anyone know where the green and purple wires from the rear speed sensor lead to so I can check continuity? The ABS controller under the hood? Any advice on which pins to test from?