Hey everyone, I have an issue with my 2002 F150 5.4 liter. I get a cylinder 2 misfire code P0352 and I thought it was the coil pack and replaced it but I was wrong. I didn't bother to test it first...my mistake. Anyways, it turns out that I am getting the pulse power going to the coil pack but not the constant power. I started getting this problem after my ac compressor and condenser were replaced by a local mechanic...along with another electrical issue that I got the mechanic to fix. I feel like this guy doesn't know his stuff so I'm hesitant to take it back to him. Rather than take it to a new mechanic, I'm trying to find the issue myself. Any recommendations on how I should proceed? I'm guessing its a short but I don't know how everything is wired and why I would get the pulse power but not the constant. And I seem to be getting power to the other cylinders just fine. Any help is appreciated.

 

check the wiring on the right side of the head area, there are some harnesses around that area that tend to short out and cause problems. especially more so if someone did some work around that area

 

Thanks I did see that and while you must have been typing your reply, I was tracing the wires back to those harnesses. I removed the connectors from the metal box they latch into and wiggling one caused me to lose pulse power temporarily. However, I never regained power to the constant. What is the fix for these harnesses shorting out?

 

Find where it is shorting and replace that wire, or isolste/insulate it.

 

There is no short. If there was, you'd have either smoke or a blown fuse. You have the opposite of a short, it's called an open.

The RD/LG wire at the COP should be HOT IN START or RUN. For bank 1, all four COPS have that wire spliced together on the RH side of the engine. If only #2 is missing power, you'll need to unbundle the harness and trace the wire back and find where the conductor is broken (or just replace that pigtail).

The "low" side of each of the coils is actually a pulsed ground signal supplied by the PCM. The coil is fired when that ground is applied. When the low side is not grounded, you should measure battery power on that line provided both the constant power and the coil are not open.

 

Thanks for the info. Yes, only number 2 is missing power. If it was a blown fuse, none of them would be getting power correct? I just want to make sure I don't go unbundling the harness if that is all it is...because it looks like a pain the butt to be honest. And the place where the wire harness clips together (on the far right side of the engine by the battery)...you are saying that the wires are all split after that and not before?

 

Sorry scratch that I don't think any of them are getting constant power. I thought they were because only one of them had an error code but now that I test on a multimeter and test light, I get no power. Could this be a blown fuse? What does the constant 12 power do because the truck doesn't have any problem starting. And why would only cylinder 2 put out an error code?

 

You seem to be getting confused.
If none had power you would have codes for all 4 cylinders on that bank and engine would hardly run.
Go back to your original code 352.
If that code is still the only one, the coil circuit from power through the coil to the PCM coil driver is "open" only on that cylinder.
All cylinders are supplied power through the same fuse. It cannot be blown if the motor starts and runs otherwise.
If coil 2 has power 'through' the coil, the lead back to the PCM is either intermittent open or there is a faulty coil driver in the PCM.
As already stated, the PCM coil driver grounds the lead to allow the coil to current saturate the core.
When the ground it opened the spark occurs. This is a way of lengthening the 'Dwell time' on the coil over the old points and condenser system of the past and is the way ignition timing is accomplished without using a distributor and plug wires.
.
Testing: The PCM coil driver has a resistance to ground that can be measured with an Ohm meter. If you remove the coil plug and measure to ground on the lead back toward the PCM you should see about 10,000 ohms +/-. If very much higher, open, or lower the coil driver is suspect after eliminating the harness and PCM plug assembly..
If intermittent during operation, a Scope to view the waveform while the engine is running is the only other way..
You have to do the testing an not look for an easy way around it.
It could be the harness plugup or even the PCM plug.
Remember the code 352 is different than a code 302. One is electrical issue of no spark due to an open circuit between battery and the coil driver as detected by a current sense in the PCM , the other is a slow rotation time after spark has been initiated that is detected by the crank sensor..
Do the testing and be sure of what you have first so your sure what kind of fault your chasing.
If a shop is contracted with the work, you would expect them to do whatever is necessary to find and repair the issue..
Good luck..

 

Okay so I think I'm testing incorrectly then. I watched a youtube video showing how to test these and so I think it may have been incorrect or based on a different model vehicle. So what I did was I took a test light originally and grounded it and then tested the two wires going to the coil plug. I got a flashing light for one side and then nothing for the other. According to the video I watched, I was supposed to get a steady light for the 12v side. So then I took a multimeter and I grounded the black wire and tested the 12V wire thinking I would get 12 volts but I got 0. But then I tested the other cables and also got 0 volts...obviously I did something wrong. Now I've already replaced the coil plugs so I don't think I would have a faulty one right out of the box. So now, from what you are saying (I want to be very clear), is that I need to ground the multimeter and test the 12V wire using the ohm feature instead and see if I get 10,000 ohms? Is that right?

Here's the video I watched... just in case you wanted to see what I was talking about

 

You never use Ohms function to test voltage. It will likely damage the meter or blow an internal meter fuse.
Lets try this another way;
12 volt source>>>>>>>coil winding<<<<<<<to PCM ground driving circuit to>>>>>it's ground which is outside common to the motor.
Use voltmeter to test for 12 volts on each side of the coil to ground. Verifies the coil is not open with the ignition on Run.
Plug up the coil, start engine. Measure for voltage on ground >(the lead going back to the PCM) > side of coil with voltmeter function. It should steady voltage pulse >downward< (if) there is no fault, each time the PCM fires that cylinder in the fire order..
If it is intermittent and your sure your test connections are solid, there is a fault in the harness, connector or the PCM driver.
The downward meter movement shows the ground is being applied and all the voltage has been dropped across the coil winding except a small amount across the coil driver circuit. How far the needle drops is a function of the meter speed of movement ability.
.
To test the line back to the PCM with motor off and coil plug off, use meter Ohms function to look back into the PCM for the resistance offered to make this test. The meter's Ohm function supplies voltage from it's own internal meter battery to detect current flow in a loop through the resistance back to the meter.
You have to get this down or we don't yet know what's going on.

 

Okay so I found a schematic and I took some pictures because I don't know what I'm doing exactly.

full schematic here

Below is a Partial schematic shown where I took measurements. From Pink/White to ground (battery negative terminal) I got 0 volts. From Red/Light green to ground I got -.20 volts. I took these measurements from the Run position. Pictures below. I also measured from the Red/light green to the Pink/white in the run position and got 0 volts.







I hope that was what I was supposed to do.

Not sure how to do this. "Plug up the coil, start engine. Measure for voltage on ground >(the lead going back to the PCM) > side of coil with voltmeter function" How do I measure when the coil is plugged in? I took a picture of the coil if that helps.




This as far as I got because I wanted to try and make sure I was doing it right. Thanks again for the help.

 

Oh I almost forgot, I did use the ohm feature to test from the Red/LT Green cable side of the connector (pretty sure that's the PCM side) with motor off and grounded to battery terminal. Here is what I got.

 

In your post #11 where you tried to measure across Red/Gn to Pink/Wht with ignition to Run and got zero volts is of course NORMAL.
It proves nothing doing that but shows you have little understanding that there will be no voltage drop to see >>>>unless current is flowing<<<<<..
Current will not be flowing under those 'static' conditions.
Your getting mired in detail you don't understand.
I see your using a Fluke meter which is a good make. but you need to pay close attention to the screen for info on what it being displayed.
We can not see that in photos, only a reading.
If you would follow my post, it will cover everything end to end for voltage and resistance readings and leaves out all the detail that would add confusion.
From it you have to deduce the fault.
Using a Digital meter to see fast pulsing of the voltage signal across a coil '' while the engine is running" is nothing but a fast moving number display as opposed to an Analogue meter where you can see the needle moving. It's just the difference you would need to know about.
I'm sorry but I can't help any further.
Good luck.

 

With the ignition switch in RUN, BOTH sides of each of the eight coils should read battery voltage (coil connected). A reading of zero volts indicates that there is an open circuit on the supply side (RD/LG wire) back to its source.

Go back to post #5.

 

The way he has it shown in post 11 circled won't read any voltage across the coil with ignition switch in RUN unless the motor is running and PCM is pulsing a ground to the pink lead.. That is a normal expectation my reply is based on.