Diagnostic direction

D an oil change and reset the dtc. Test to see if code comes right back.

Does the vehicle have VVT ? IF yes, question the customer. Have they been having any issues. weather intermittent or constant. Their is multiple different reason that code can come on from my past experience. So knowing what has been happening with the vehicle from the customer point of view is key. And make sure that the person driving the vehicle is answering . eg if the son drives it 99%…

Ive been kicked hard by these engines a few times. First step I tell people now especially if its low on oil and you don't know the history is to change the oil and put an manual oil pressure gauge on the engine and see what the oil pressure is when the engine warms up. If it drops below 25 psi don't spend any time putting any parts into the timing chain...engine is already probably toast...

If you have high AC ripple it can cause DC electrical issues. Such as cam sensors not giving accurate signals to computer making the computer think their is a problem with that component when their isn't. I personally have not had this issue with these codes, but it is a sound theory and something I will keep in my notes for future use now.

That's right...Even learned that this weekend that DC doesn't like a lot of AC ripple. If you want to refer to Fords TSB 06-19-12 that is what i'm referring to.

I been taught that no more then 250 mv ac. Normally I see 100 or less. That is all possible loads turned on at idle and at … RPM. Those numbers have worked good for me so far. But like I said before I would question the customer first before spending too much time. Since you have pico it seems. I would also check voltage on say the data connector and see if you have excessive AC voltage…

Could I use a break out box to check this? Figured it would be easier with a B.O.B

That's what I would use if you are going to do it and have one available.

I updated the file here 119.3mV at the BOB.

Had on 06 Mustang that had this problem. Had the sensors replaced several times by others. New Motorcraft Alternator fixed problem. Was very strange.

RFI from the alternator can corrupt the CMP signal.

If the alternator is leaking ac(ripple) it could and will effect sensors and other devices​.​So will coolant electrolysis where as the coolant gets old it has the ability to give off a low voltage(milivolts) which can effect sensors.

This is a circuit DTC, not a performance DTC. Look for circuit or sensor issue. Possibly a reluctor fault. Agreed on the AC ripple discussion. A DSO can be a great test tool here. A failing phaser or base oil pressure should not contribute to these DTCs but these DTCs may block performance monitors. Check SI to be sure.

Hi Randy I referenced tsb 06-19-12. Will post results soon

Thanks Michael. I'll follow...

I have been fooled by this code before, chased down circuits and tested sensors with no problems found. But when comparing cam to crank correlation with known good found had a timing issue. For some reason on some years of these engines the code description says circuit and is actually a performance issue.

I have had similar experiences with these dtc's but not sure if it was on this year.

same as Clinton quick check with scope confirmed timing issue on the last one i had.

Have you tried to even diagnose this issue? References Service information to do diagnostics?

Is checking for tsb's not part of the diagnostic process? It is for me.

Matt I really don’t find any value in a response like this. The man asked specifically for diagnostic direction. Can you help him with that? Or does it make you feel like a bigger better tech to knock him down a peg?

I see both sides of if this situation. On the one hand, if you dont have the wherewithal to look up the code and at the very least follow the trouble tree before throwing your hands up in surrender,why bother attempting diagnostics at all? I view this site as helping diag techs move forward, not holding their hand from the beginning. Some legwork should be done first. On the other hand, youre…

What’s wrong with trying to find out if he has done the basics to know where to start? My response is just as helpful as the information he gave. it’s low on oil, did he fill it and retest? Did he do the basic trouble tree diag to be able to give him a direction if it didn’t help? Basically with the codes I could point him to the basic code description and tell him to do the diagnostic routine…

Had I tossed parts at it and nothing fixed it I can see an issue with asking for help after the fact. Checking tsb's is the first thing I do. If you guys don't agree with that then that's fine. I also don't think the guy "tore me down" no offense taken.

I disagree. You weren‘t just trying to find out what he had done. You pulled the Facebook social media response of do you even diag bro type of derogatory comment. He didn‘t ask for a silver bullet. He wasn’t asking for an auto zone diag. He was looking for diagnostic direction. We need to learn how respond like Randy did. That is how professionals do it. Screen shot in case you missed it.

JM said; "I disagree. You weren‘t just trying to find out what he had done." So you are a mind reader now Justin? Cool!

I have seen lots of alternators cause this on these. I agree with what other’s have said. Start with checking AC ripple from the alternator.

Even with a TSB and knowing the DTC is supposed to be for a circuit issue, I have read multiple cases, both on iATN and in classes, where the definition of "circuit" was loosely used by the OE and the word "system" would have been better. My overall experience is that a PCM cannot be trusted to self-diagnose electrical issues on a mechanically faulted engine (like no oil....or just plain old…

I neglected to add that an oil service was on the repair order even before we were troubleshooting this.

Roger that. Always helps to include everything. It helps stave-off all the arguing about the "quality" of any given post and the "tone" of any given response. Even if you write, "I ran every test in the book" someone is gonna ask "which book?" and "which tool did you run 'Test ABC' with?" Let us know how it turns out. :-)

Damned if you do damned if you don't. Will post results tomorrow.

Michael; Good evening Sir, I hope this email finds you doing well. I don't know if the attached document will help you diagnose your issue but it should help you gain a better understanding of what you're working on. The attached article is an Engine Mapping Tech Tip written on Ford's 5.4 Liter V8 SHOC Variable Camshaft Engine. The article isn't complete yet and i apologize for that but when i…

Thanks Jonathan, much appreciated.

Anytime I see Cam or Timing codes on a VCT Ford always check the VCT timing, VCT Error and VCT desired PID's and see what the data says. Most of the time this will point you in the correct direction of mechanical or electrical problems.

Hello Michael. Have these codes returned have you been able duplicate them? Anyway I will try to answer a couple of your questions as best I can. First the cam sensors on this truck are actually 2 wire variable reluctance sensors that produce there own AC voltage,not DC. I would assume thats why they more susceptible to interference?? I don't know but seems like it might play a factor in this. I…

So far so good. No codes returned. I appreciate your time in explaining it and yes, I will get a cam/crank and report back.

I was following along and not sure if I missed something. (the fix?) Last post I read from Michael was so far so good.

Fix was a new alternator from Ford. Followed up with the customer yesterday and no other issues came up.