2015 coyote users help please

[wareaglescott]

I have been having some issues with my pcm. Been working with Ford tech support tracking down the fault. They seem to think the issue stems from my MAF sensor. Really long story but I do not agree.
One of the test they had me do today was to unplug the MAF sensor plug, turn the key to the run position(one click to right) but do not attempt to start and put a multi meter on the green wire in the MAF plug to read the voltage.
They indicate it should be 12V with the red probe touching the green wire and the black probe to a frame ground. The green wire is the third one over in the plug. Mine indicates 0.45V for the green wire and the one next to it which is purple shows 5.0V.
(now for reference I have a 2012 F150 with a 5.0 I unplugged it and checked that wire and it was in fact 12V)

My belief is because the way the coyote and Ron Francis harnesses are integrated and for whatever reason that is beyond my understanding I don't think it gets the 12v at the MAF until you are actually trying to crank the motor not in the accessory position as Ford is telling me it should be. Getting Ford tech support to agree with that assessment is another matter because naturally they do it every day and most likely think I am a moron when it comes to this stuff. (probably a fair assessment on their part! haha)

I am trying to collect data to see if other coyote users are getting the 12v or something like I have. I have messaged with another forum member and his results mirror mine. Furthermore I have had flawless operation up until now and don't believe anything has changed with regards to the voltage going to my MAF sensor.

So if anyone has a running 2015 coyote in there garage and would be willing to unplug the maf sensor and turn the key to the run position only and read the voltage I would be very appreciative to hear your results. Please post them here.

Thank you to anyone that can help.

[edwardb]

My Coyote build is at the painter, so I can't also test mine. But I'm not surprised you aren't getting 12 volts at the MAF sensor with the key in the accessory position. The way we have these wired, the RF orange EFI/COIL wire is connected to the Coyote pigtail light green ignition relay trigger. This is the wire that energizes the ignition relay and "wakes up" the system. In the RF harness, the EFI/COIL wire is part of the IGN FEED circuit, so only is powered when the ignition key is in run or start. It is NOT powered when the key is in the accessory position. You should be able to get the MAF measurement they're asking about with the key in the run position. If somehow Ford doesn't like this setup, my only response is many are wired exactly like yours and run perfectly. HTH

[wareaglescott]

My Coyote build is at the painter, so I can't also test mine. But I'm not surprised you aren't getting 12 volts at the MAF sensor with the key in the accessory position. The way we have these wired, the RF orange EFI/COIL wire is connected to the Coyote pigtail light green ignition relay trigger. This is the wire that energizes the ignition relay and "wakes up" the system. In the RF harness, the EFI/COIL wire is part of the IGN FEED circuit, so only is powered when the ignition key is in run or start. It is NOT powered when the key is in the accessory position. You should be able to get the MAF measurement they're asking about with the key in the run position. If somehow Ford doesn't like this setup, my only response is many are wired exactly like yours and run perfectly. HTH

Thanks Paul
I was wondering about getting the reading with the key in the run position. I sure didn't want to try unplugging the MAF plug completely while the car was running to be able to check it. Was not sure what the consequences on engine operation would be. Will forward this information to Ford and see what they say.

[CraigS]

The engine doesn't need to be running for the key to be in the run position. If Ford powers this wire in acc position that is fine but in 20+ years as a Lexus tech, I never checked anything relating to engine control in acc. It was always done in run. Perhaps they want that extra fraction of a second in a regular key activated start sequence to wake up the system as Paul mentions. WHo knows what happens in a regular 2015 Mustang w/ a push to start button.

[edwardb]

The engine doesn't need to be running for the key to be in the run position.

Exactly. That's what I meant. Rather than turning the key to the ACC position to take the measurement, turn it to RUN. But don't start it. Then take the requested measurements. Sorry for the confusion.

[wareaglescott]

The engine doesn't need to be running for the key to be in the run position. If Ford powers this wire in acc position that is fine but in 20+ years as a Lexus tech, I never checked anything relating to engine control in acc. It was always done in run. Perhaps they want that extra fraction of a second in a regular key activated start sequence to wake up the system as Paul mentions. WHo knows what happens in a regular 2015 Mustang w/ a push to start button.

Craig you have to dumb your responses down to my level please!
If I am trying to check the power with the key in the run position how do I get the key there and power on without the engine starting?

When I am saying accessory I am meaning the first click to the right. The next click to the right cranks the motor. My key also goes one click to the left. Maybe that is the accessory position and I am describing this incorrectly?? My previous testing has been done with the key one click to the right.

[edwardb]

Craig you have to dumb your responses down to my level please!
If I am trying to check the power with the key in the run position how do I get the key there and power on without the engine starting?

When I am saying accessory I am meaning the first click to the right. The next click to the right cranks the motor. My key also goes one click to the left. Maybe that is the accessory position and I am describing this incorrectly?? My previous testing has been done with the key one click to the right.

ACC is one click to the left. Only a certain number of circuits are active at that point. RF schematic shows which ones. RUN is one click to the right. All circuits are alive then.

START is an additional turn to the right. In the Coyote setup using the Controls Pack to control the start function, turning the key to start initiates the same sequence as the pushbutton start in a Mustang.

[wareaglescott]

ACC is one click to the left. Only a certain number of circuits are active at that point. RF schematic shows which ones. RUN is one click to the right. All circuits are alive then.

START is an additional turn to the right. In the Coyote setup using the Controls Pack to control the start function, turning the key to start initiates the same sequence as the pushbutton start in a Mustang.

Ok thanks Paul. I was stating it wrong then. I was testing yesterday in the RUN position and not accessory. I will correct the wording in my initial post and if anyone is able to test it in the run position that would be appreciated.

[totem]

The MAF has it's own fuze, powered when ignition is on. At least on the Mustang 2011 wiring diagram. It's not powered by an ECU pin.

You should have power with key on/engine not running.

Try to trace the green wire to the fuze box.