Testing injector wiring

[Joe Dirte]

I'm gonna unplug the main harness from injectors n test it to see if maybe I have a broken wire. I'm thinkin the key has to be on, probe the pin hole with positive lead n ground lead to a ground it should read voltage. Am I right or do I have it backwards?

 

[JeremyNH]

You don't mention year or engine. For the L31 you are correct in that 12V to the injectors are always on (comes through two different fuses) and the PCM turns on the injector by switching in/out the ground. It would be more complete to test at the PCM though vice at the spider harness since you could have an open in the harness not just the wire. For the 1998 L31 the PCM wires are in the C2 connector, pins as follows:

Wire Color	Circuit No.	Wire Function	PCM	Connector	Pin
BLK	1744	Injector # 1 Control	OBD2	C2	8
DK.BLU/WHT	878	Injector # 8 Control	OBD2	C2	9
LT.GRN/BLK	1745	Injector # 2 Control	OBD2	C2	11
RED/BLK	877	Injector # 7 Control	OBD2	C2	12
BLK/WHT	845	Injector # 5 Control	OBD2	C2	15
YEL/BLK	846	Injector # 6 Control	OBD2	C2	16
LT.BLU/BLK	844	Injector #4 Control	OBD2	C2	31
PNK/BLK	1746	Injector #3 Control	OBD2	C2	32

 

[Joe Dirte]

Thank you. I thought it was a ground fired injector but wasn't 100%. It is a 98 with an L31 with a constant misfire on #5 with spark and a good injector. Other than maybe the wire bein broke maybe the valves need adjusted but 2 motors havin same issue I'm thinkin wiring. I could probly do continuity test if I find where it's fed from too correct? I'm not good with electrical so I wanna make sure what I'm doin before I mess anything up.

 

[JeremyNH]

This may help. Going from memory when I converted to cpc I thought it was two fuses but looks to be only one.

You must be registered for see images attach