I don't have a book for the truck. so can someone post a pic for a 1990 truck3.0 and NOT a 4runner PLEASE. im trying to check continuity on knock sensor wire and don't know witch it is at the ecm.

 

I haven't got that page, but from the wiring diagram the knock sensor is a black wire and it's pin location is T3-5 (16 pin grey connector) if it's an auto with ECT. Or it's location is
T4-17 (24 pin grey connector) if it is an auto without ECT or a manual.
If the connectors are still plugged into the ECU and you are looking at the wires coming out of the connector pin #1 is top row right and is numbered from right to left, the second row numbers are right to left as well. Ex. T3 16 pin...pin 9 is below pin 1.