No power to coils
May 12, 2018, 10:58 PM
#1
No power to coils
short version is i have zero spark. Upon further investigation my coils are not getting any power. I started the car a few days again and it just died and never started again. I have replaced cam and crank sensors as well as tried stock coils and spark tech COP. The fault is the same as it cranks and will not fire. Is there a relay for the coils somewhere?
car is a 03 Evo garage.
car is a 03 Evo garage.
May 13, 2018, 08:00 AM
#3
EvoM Community Team Leader
So there is power and signal, based on the parts you said you have replaced that makes me think you meant signal, but if you could clarify that would be helpful. At any rate
https://drive.google.com/file/d/1k3l...ew?usp=sharing
for some reason i can't upload an image so i linked my wiring diagram for the ignition circuit.
https://drive.google.com/file/d/1k3l...ew?usp=sharing
for some reason i can't upload an image so i linked my wiring diagram for the ignition circuit.
May 13, 2018, 08:44 AM
#4
So i have power and signal to the cam and crank sensors. I have even swapped with new sensors to be sure. When i place the tester at the coils i get zero voltage. I check for spark on the cop and stock coils as well and get nothing. My injectors are firing as i have fuel in all cylinders. So there is no power getting to the coils at all. I’ll check out the diagram.
I have checked that fuse fuse but to be 100% sure i will replace with a new 15A fuse as stated above.
Im starting to lean towards a wiring issue or ECU.
I have checked that fuse fuse but to be 100% sure i will replace with a new 15A fuse as stated above.
Im starting to lean towards a wiring issue or ECU.
May 13, 2018, 10:46 AM
#5
EvoM Community Team Leader
So i have power and signal to the cam and crank sensors. I have even swapped with new sensors to be sure. When i place the tester at the coils i get zero voltage. I check for spark on the cop and stock coils as well and get nothing. My injectors are firing as i have fuel in all cylinders. So there is no power getting to the coils at all. I’ll check out the diagram.
I have checked that fuse fuse but to be 100% sure i will replace with a new 15A fuse as stated above.
Im starting to lean towards a wiring issue or ECU.
I have checked that fuse fuse but to be 100% sure i will replace with a new 15A fuse as stated above.
Im starting to lean towards a wiring issue or ECU.
May 13, 2018, 11:58 AM
#6
Im gonna to start with tracing from the ignition to that 10 amp fuse. My guess is i have a break in a wires somewhere or some corrosion. For grins and giggles i tried flashing another ROM and i got the same results with the no start.
May 13, 2018, 12:11 PM
#7
have you tried jumping battery positive to the coil feed to allow it power? This would just be for troubleshooting of course.
I can't imagine the evo would have a computer controller power feed for the coils, so I would think the ECU would be something you could ignore completely.
I know certain OEMS use a relay that is computer controlled. Once the ECU see's an rpm signal from cam and crank it powers up the injectors, coils and other hardware- but I don't THINK the evo is that advanced.
I could be wrong.
I can't imagine the evo would have a computer controller power feed for the coils, so I would think the ECU would be something you could ignore completely.
I know certain OEMS use a relay that is computer controlled. Once the ECU see's an rpm signal from cam and crank it powers up the injectors, coils and other hardware- but I don't THINK the evo is that advanced.
I could be wrong.
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May 13, 2018, 12:46 PM
#9
I think that C-129 is common for "electrical gremlings"
https://www.evolutionm.net/forums/ev...s-how-fix.html
https://www.evolutionm.net/forums/ev...s-how-fix.html
May 13, 2018, 01:21 PM
#10
You have to remember- if you have a corrosion problem, you MUST test the circuit when it is LOADED.
Voltage measurements are not enough, the circuit needs to be carrying a current to understand if it is able to carry a load.
If you have a wire with high corrosion (green-cruddies) it will many times show voltage with a voltmeter, but when it comes time to carry a current the voltage will drop significantly.
Scanner-danner on youtube has EXCELLENT videos that have training on this exact subject. I HIGHLY recommend them.
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JUANPSI (Dec 15, 2023)
May 13, 2018, 03:11 PM
#11
EvoM Community Team Leader
have you tried jumping battery positive to the coil feed to allow it power? This would just be for troubleshooting of course.
I can't imagine the evo would have a computer controller power feed for the coils, so I would think the ECU would be something you could ignore completely.
I know certain OEMS use a relay that is computer controlled. Once the ECU see's an rpm signal from cam and crank it powers up the injectors, coils and other hardware- but I don't THINK the evo is that advanced.
I could be wrong.
I can't imagine the evo would have a computer controller power feed for the coils, so I would think the ECU would be something you could ignore completely.
I know certain OEMS use a relay that is computer controlled. Once the ECU see's an rpm signal from cam and crank it powers up the injectors, coils and other hardware- but I don't THINK the evo is that advanced.
I could be wrong.
May 13, 2018, 11:43 PM
#12
So hooking power from the battery to each white wire with the red stripe on the coil connectors produces power and spark. I was able to start and drive the car this way. Thanks for that suggestion.
Now time to trace where i am losing power at. I will start with C129 as that seem to be the most common problem.
Now time to trace where i am losing power at. I will start with C129 as that seem to be the most common problem.
May 14, 2018, 01:02 PM
#14
EvoM Community Team Leader
Yah thats right pin 18, what also helps is the color coding, you can see it goes in "Y-G" (Yellow-green) and comes out the other side "w" (white)
May 15, 2018, 11:54 AM
#15
Long story short...it ended up being the fuse after all. Visually it doesn't look blown. I put the tester on it and no power. Replaced with a 15 amp and all is well. It seemed to separate at the side...never seen that on a fuse before and not sure how that even happened. All is well now......thanks for all the help and documentation.
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