2010 Yukon XL 5.3 No Power to Coil

slyhog022056 said:

Hello again people. I am trying to get my 10 Yukon back running again. It was crashed and totalled a few months back but still ran. Replaced needed and got it going. I was driving it around over 200+ miles to set the IM for vehicle inspection. Ran fine until all of a sudden it had a cyl 4 misfire and the usual traction control lights come up. Checked for spark and had none. Swapped coil, plug wire and plug... Nothing. Called a GM tech and he gave me general voltage info at the coil plug pin 1 gnd, pin 2 12vdc. I only have ground, not 12 volt reference, no trigger signal. I want to trace out the wires but cant find a wiring diagram with the correct pinouts at the ecu and coil. all I can find id the wiring to IC4 control pin #76 Dk Grn/ Wh. that much i understand. the plug on the coil does not have a Dk Grn/ white wire on it. I want to try and trace out this circuit before I have to spend $250 for another ECU.

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Doubeleive said:

the coil pack harness is where you want to start, the harness can be replaced if determined to be bad, or fix the break in the wire.
usually it is the ground that goes bad

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slyhog022056 said:

The "tech" i talked too told me everything was referenced to ground. Ohmed the black wire out and it was grounded. Engine running I am supposed to have a 12 vdc signal one pin 1, pin 2 is supposed to be trigger. cant detect that with DVOM. started probing with scope and have no 12 vdc or trigger on that plug only. I dont know how the harness runs on this thing but I want to check every connection end to end before spending money on a ecu. Checked the pinouts on the ecu plug and the wire colors according to GMC do not match at all. I do have 2 other vehicles that I can use but I like my Yukon mainly because it can tow more than my 3/4 ton truck.

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Doubeleive said:

the coil requires 12v to fire, ground is common for 4 on one side and 4 on the other side.
the ecm is not going to fire 7 of them and not the 8th, broken wire somewhere
start by checking continuity between the coil and the harness connector
like this
View attachment 440744

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slyhog022056 said:

I have continuity from coil to that connector all 4 wires. Between there and ecu is where i lose it. Could not locate the trigger wire st ecu plug with those colors

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