Need help what is the pin out for this plug can’t find anything on it, I trace the wire all the way to a plug underneath the dash it looks like a red plug that is a junction box, The plug is cut off on the actual engine harness and I need to Figure out what connects to in the engine bay it’s a solid yellow wire, is it a power wire

 

This is connector C212 on the chassis harness side (connects to C153 on engine harness side). Here is what I dug up from my files. I'm not sure of the purpose of the YEL, GRN/BLK, and YEL/GRN wires.

YEL
WHT - Ignitor. Runs to B15/B17 on ECU.
RED/WHT - ECT. Runs to C6 on ECU.
GRN/BLK
YEL/GRN
RED/YEL - IAT. Runs to C5 on ECU.

 

For a 91 Si, that is Connector C217.

Terminal no. - Wire color

1 - Red/Wht : Coolant Temperature Sensor (TW) Input to ECU

2 - Wht : Ignition Output signal from Igniter to ECU

3 - Yel : Under-dash Fuse No. 1 (power to back-up lights switch)

4 - Red/Yel : Intake Air Temperature Sensor Input to ECU

5 - Yel/Grn : Coolant Temp Switch (cooling fan switch)

6 - Grn/Blk : from back-up lights switch to back-up lights