95 7.3 injector harness/pigtail problem

[Strokin8834]

Ok a couple weeks ago I pulled the valve covers because of the issue with the uvch and gaskets. all looked well and was plugged in and not loose. Truck is idling rough and running rough but it still runs around ok. Keep in mind ive only had it a couple weeks and have been slowing working through all obvious issues. Anway I thought I would unplug each of the 4 pigtails one at a time with the truck running and see if I could notice a difference on a certain one. Well the front passenger side pigtail when unplugged made absolutely no difference which makes me think I am running on 6 cylinders. is there a way to test this pigtail with a volt meter? if so what setting and what volts should I be getting? any help would be greatly appreciated.

[Strokin8834]

this Is the pigtail on the outside of the valve cover that plugs in to vc gasket.

[Patrick Feeley]

Start by testing from the valvecover connection to the injectors. On each connector the middle pin of the five is the injector common (common to two injectors). The immediately adjacent pins are for one injector each. The outer pins are for glow plugs. You should not get any continuity between the either of the outer pins and any of the 3 injector pins. With the resistance setting on the meter set to the lowest setting, you should get a reading of 2-3 ohms between the center pin and each adjacent pin (the resistance of the injector solenoids). If those check OK, you might need to check going from valvecover harness connector back to the IDM connector (a little more involved). Let us know what you get on the first part. Cheers!

[Strokin8834]

ok Patrick I gotta be honest I mechanic alright but this electrical stuff gets over my head.... I set my volt meter to lowest ohm setting which I think is what we want. I checked the female end on the outside of the valve cover gasket. I kept the negative probe on center pin and went from pin closest to grill all the way to pin closest to cab. First pin which should be gp showed nothing, second pin showed 3.2 fourth was 3.2 and last pin showed nothing. Is this correct or should glow plugs show something too? does this mean its the pigtail not the uvch?

thanks

[Patrick Feeley]

That is how they should be. Most likely the external pigtail (or an Injector Driver Module, IDM) problem. If I get the chance, I'll see if I can post the info for going the opposite direction. Cheers!

[Strokin8834]

That would be great thank you

[Strokin8834]

any ideas on how to test from valve cover outside pigtail to idm anyone? I picked up a uvch with the external pigtails but uvch tested good so I need to test from uvch back.
thanks

[Patrick Feeley]

Sorry, had to go out of town last night, but I should be able to get to it tonight (maybe someone will beat me to it). Cheers!

[Patrick Feeley]

Here is the wiring from VC connectors out to the IDM connector:

Valve Cover Wiring to IDM Connector Pins

For the #1 and #3 Injectors (passenger side front):
VC connector middle pin (Injector #1 and #3 common, Orange wire) to IDM connector pin #24
VC connector adjacent pin (Injector #1, Teal wire) to IDM connector pin #6
VC connector adjacent pin (Injector #3, Brown wire with Yellow trace) to IDM connector pin #21

For the #5 and #7 Injectors (passenger side rear):
VC connector middle pin (Injector #5 and #7 common, Orange wire) to IDM connector pin #24
VC connector adjacent pin (Injector #5, Teal wire with Black trace) to IDM connector pin #8
VC connector adjacent pin (Injector #7, Teal wire with Red trace) to IDM connector pin #20

For the #2 and #4 Injectors (driver’s side front):
VC connector middle pin (Injector #2 and #4 common, Pink wire with Yellow trace) to IDM connector pin #23
VC connector adjacent pin (Injector #2, White wire) to IDM connector pin #22
VC connector adjacent pin (Injector #4, Brown wire with Light Blue trace) to IDM connector pin #7

For the #6 and #8 Injectors (driver’s side rear):
VC connector middle pin (Injector #6 and #8 common, Pink wire with Yellow trace) to IDM connector pin #23
VC connector adjacent pin (Injector #6, Light Green wire with Orange trace) to IDM connector pin #19
VC connector adjacent pin (Injector #8, Light Blue wire) to IDM connector pin #9

Cheers!

[Strokin8834]

Awesome thank you!