There is a second harness on the engine that connects to the two guage sensors for coolant temp and for oil pressure, to the oil level sensor on the pan.
this harness runs down the back of the engine to the top of the trans.
If you havd an auto trans, the wiring goes to the Neutral safety switch
On a '91-92 it goes to the switches on a manual trans, the neutral sense switch and the reverse light switch, on a 1993-94 it runs only to the reverse light switch, because 1993-94's don't have the Neutral Sense Switch.
The Manual trans harness has a loop of pink wire at the connector to jumper the neutral safety switch. as a note your truck originally an auto will have the clutch safety switch connector (Actually the clutch multifunction switch), but will have a factory installed jumper cap in the plug...
The two smaller plugs that connect this "Trans & Guage" harness to the main harness will be found clipped to the drivers side inner fender directly below the brake master cylinder.
I recommend just locating a donor vehicle for this harness, it changed over the years and some years include the Light blue wires that go to the 4x4/4Lo indicator switch on the manual t-case, later years include the wiring harness extension to the Cat monitor sensors...
Trace the wires and simply disconnect everything...
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