PO354 bad COP
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Member
Joined: Dec 2009
Posts: 17
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From: Bend, Oregon
PO354 bad COP
I used the auto parts store diagnostic and it gave this reading- PO354 Ignition coil D.
I thought it was a bad coil (I just changed all 8) & I hoped it would tell me which one was bad. Does Ford use A B C D E F G H instead of 1 2 3 4 5 6 7 8? If so which one would be D, number 4?
Any ideas, if not I just start changing 1 at a time tomorrow. Thanks
I thought it was a bad coil (I just changed all 8) & I hoped it would tell me which one was bad. Does Ford use A B C D E F G H instead of 1 2 3 4 5 6 7 8? If so which one would be D, number 4?
Any ideas, if not I just start changing 1 at a time tomorrow. Thanks
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Joined: Jul 2004
Posts: 6,200
Likes: 39
From: Easton, Pa.
Yes D is cylinder 4 on passenger side rear..
The PCM detects a coil primary fault.
Check coil 4 with an ohm meter for an open accross it's plug terminals.
If changing the coil does not clear the miss, you need to test for 12 volts between the plug connector with the ignition switch to 'run', and ground.
Note all coils are powered from the same fused source so a no voltage could be an open harness.
If ok , then you should test resistance looking back at the PCM on the other lead to ground with the igniton 'off'..
You should see at least 10,000 ohm and no less, preferably an open.
It is possible for the driver to be faulty and not switch a ground (open) so another test would be to see a pulsing ground upon cranking.
If you see a very low resistance or no pulsing, get you wallet out and be prepaird to spend for a PCM and service.
If the coil driver is shorted or open it is being detected by the diagnostic part of the PCM program.
What is involved with replacing the PCM is programming it to your trucks build spec and the PATS system with the original 2 keys you should have.
This is all dealer work.
If it come to this, they will test all drivers and coils and harness before replacement so there is little chance of having more trouble due to not testing everything out.
BTW do not drive the truck with a cylinder out. You will overheat the cat on that side and burn it out from raw fuel being burned in the cat then there is more expense yet..
Let us know what happens.
Good luck.
The PCM detects a coil primary fault.
Check coil 4 with an ohm meter for an open accross it's plug terminals.
If changing the coil does not clear the miss, you need to test for 12 volts between the plug connector with the ignition switch to 'run', and ground.
Note all coils are powered from the same fused source so a no voltage could be an open harness.
If ok , then you should test resistance looking back at the PCM on the other lead to ground with the igniton 'off'..
You should see at least 10,000 ohm and no less, preferably an open.
It is possible for the driver to be faulty and not switch a ground (open) so another test would be to see a pulsing ground upon cranking.
If you see a very low resistance or no pulsing, get you wallet out and be prepaird to spend for a PCM and service.
If the coil driver is shorted or open it is being detected by the diagnostic part of the PCM program.
What is involved with replacing the PCM is programming it to your trucks build spec and the PATS system with the original 2 keys you should have.
This is all dealer work.
If it come to this, they will test all drivers and coils and harness before replacement so there is little chance of having more trouble due to not testing everything out.
BTW do not drive the truck with a cylinder out. You will overheat the cat on that side and burn it out from raw fuel being burned in the cat then there is more expense yet..
Let us know what happens.
Good luck.
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Member
Joined: Dec 2009
Posts: 17
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From: Bend, Oregon
Thank you for all the info. I removed coil #4 replaced it with the new one installed in #1 then grabbed one of the old Motorcraft coils that I had replaced & put it in #1. Truck runs great now.
It was a bad cop from Uneek, I'll see if they will replace or I'll just buy a single from somewhere. It's terrific to have guys like you that will help old wrench turners like me.
Thanks again!!
It was a bad cop from Uneek, I'll see if they will replace or I'll just buy a single from somewhere. It's terrific to have guys like you that will help old wrench turners like me.
Thanks again!!
