Check the wire harness that goes from the engine to the pcm on the driver side where it routes under the air filter and to the pcm and see if there's any wires chaffed. Also on the intake manifold drivers side check the studs to make sure they didn't puncher threw the convoluted tubing I to the wiring

Sent from my XT1650 using Tapatalk

 

I've always hated using ohms. Resistance should be an absolute last resort for testing. Especially when testing for a signal. Always use voltage whenever possible.

Start at square one, the cam/crk sync. Since you tested it at the pcm, I assume you know which pins are the signal wires for cam and crank. If so do this instead, hook red lead of volt meter to cam signal at the pcm connector, use a pin to back probe for this. Then hook black lead to battery neg. Put a socket on the crank bolt and spin the engine over by hand with the key on. You should get a digital 5v signal. 5,0,5,0,5,0. Anything other than that and there's a problem.

Do the same thing for the crank signal. If you have both signals reaching the pcm, but still no cam crank sync, you have a bad pcm. I'm guessing you're loosing signal somewhere, but you need to verify that first.

 

I've gone over as much of the harness as I could get hands and eyes on, there are some rubbed spots but no penetration or breaking that I could find. They really got creative with the routing to the lower sensors.

I will get the harnesses all plugged back in and give that a shot with the volt meter.

Thanks for the input, I'll be back with results!

 

Yeah do, because there is absolutely no point in looking for a short or open if the signal is there right? That would be like checking why you've lost spark, without even knowing whether or not you in fact did loose spark. First establish whether signal is actually getting to the pcm or not, then figure out why. Looking for a short or open in wire looms will make you hate life if you do it for no reason.

There's also no need to look through all the wires, but we'll get to that later.

 

Getting back to this again...

I kind of feel like an idiot here, it looks like I have to pull the fan to get to the crank bolt. Am I correct there?

If I had someone turn the key while I probed, would a volt meter register the signal or does it send in too short of bursts to register on a volt meter while it's spinning that fast?

 

Good question. Two things you can do. You can get a 24mm socket with a flex wratchet on the alternator instead and turn it that way. It'll only spin the engine if you turn the ratchet counter clockwise so keep that in mind. If you spin the ratchet clockwise from the alternator, the tensioner will slacken the serp belt and the crank won't spin.

Alternatively, you can have bump the key several times. Just bump, let the key go, bump let it go. Because yes, your meter won't be fast enough to read a digital signal at those speeds. You'd need a lab scope for that, which is what I now use. But for the first ten years, I did it in one of the two ways I just mentioned. If you choose to bump the key, just make sure you bump it enough to actually spin the crank a bit. If you don't bump it enough, it won't overcome the compression and will just spin a bit and spin back, which could give you a false reading.

If in doubt, try the alternator method and look down at the crank and be sure it is spinning. Once you know for sure it's spinning, look at your meter and look for a 5,0,5,0. If it doesn't read that, and only that, double and triple check your connections and try it again. Of it still doesn't work, then try the same thing at the sensor itself. If you don't get it at the sensor, the sensor has either lost power, or is faulty. If you do get it at the sensor but not the pcm, the signal wire is bad. If you get it at the pcm and still show no sync, the pcm is bad.

 

Don't forget to check with the key on.

 

Ok, had a chance to dig in and have some data. Not quite sure where to go with it.

Using the alternator method, I measured CMP+, CKP+, CMP- and CKP- at the PCM connector. I am using page 3 in this pinout (hxxps://app.box.com/s/38db5e11b446942bcf7d) to locate the correct wires in the connector. I am using pins 30,31,41,43

While turning the alternator with a ratchet, both CMP+ and CMP- would go between 3.02v and 3.03v. CKP+ and CKP- would measure 1.54v - 1.55v while turning. At no point did the meter read 0v on any of those pins with the key on.

 

Standby, looking up the diagram now. Sounds like it may actually be an a/c sensor.

 

Okay, so it indeed is a two wire sensor, I apologize for that. So now, just hook back up to ckp+ and ckp- and set meter to A/c vots. Then crank the engine and watch the meter. It should show an A/c voltage of some kind. It isn't much, say between 200 milivolts and 1v. Or .200 to 1.000 vac

Do the same for the cam

Edit: and those funky voltages you were reading were from a bias voltage, disregard those.

 

I will give that a shot, getting the work lights out now.

Is there a range I'm looking for (the 200mV - 1V) or is it a "if you get something, it's good" test?

 

Ummm, yes....and yes. There's no telling what it will be, but it should be at least 200 mv and may be higher, but I doubt it. I have seen lower but it's very rare. And I've never seen higher than .800. Hell, AC sensors in general pretty rare nowadays. But yeah, look for at least .200. Post back with the results.

 

I couldn't get good enough lights on it and the weather man made good on his promise of rain so I had to give up for today. I will get at it first thing in the morning and get some results.

 

When you install crank or cam sensors the engine block must be very clean. You must get cam/crank sync first, then the ficm sync will follow.

 

Yes, when I replaced the sensors I made sure the block was super clean and everything fully seated.

Right, the trouble is getting that cam/crank sync and that's where I'm stuck and why this thread exists

 

Back but with less data this time. I don't believe my multimeter is sensitive enough. I was unable to get any Vac readings from either sensor.

Since I had been messing with the wiring so much, I decided to crank on it just to see if there was something that got moved that might have been damaged that I hadn't noticed.

I got sync and FICM sync for about 2 frames on my ScanGauge then both dropped back to 0. All other readings were good during cranking.

Thoughts? Any other ideas to try?

 

I promise your meter is sensitive enough. Did you back probe at the connector? Because it can be difficult to make a connection with back probing. This is the part I was talking about when I said to double and triple check the connections. Squeeze it in between the wire and rubber seal and push it down as far as it will go, but don't force it. try above the wire, below it left or right, it needs to go down in there a good distance and should not need to be forced. As soon as you get it in the right spot, it'll slide right in with little force and stop when it bottoms out. It's not piercing wires or anything like that, merely touching the pin.

Secondly, what do mean you got sync by cranking on it? Like you think you got it from moving wire looms around and wiggling stuff while cranking? Because that's a legitimate test. Wiggle the connector and wires while cranking. But there's no point in doing that if the signal is there. You must establish whether or not the pcm is receiving signals from the cam and crank.

Lastly, there's nothing else to be done at the moment, sorry guy. This step must be done correctly. The what is no cam crank sync. You have to establish the why. Don't get discouraged, this is pretty advanced stuff. Most techs don't have the first idea how to diag anything electrical. 98% of the techs I've met would simply start throwing parts at it, all on the customers dime. So take your time, don't get frustrated and you'll save a ton of money and heart ache in the end. A misdiagnosis here will be devastating.

 

Yes, I was back probing at the connector. I double, triple, quadruple checked connections and made sure they were good by switching back to ohms on the multimeter and getting the same reading as I did when I was testing with the connector pulled and probing the connector directly.

Right, I'm not sure if it was from moving the wire looms around or not but I'd never noticed sync before today. I wasn't moving the wire looms around while cranking but with all the plugging, unplugging, testing, etc that I've been doing I figured I'd just crank on it and see what happened. It took about 3-4 times of cranking for 10-15 seconds and I got that sync then ficm sync, held for a second then both back to 0. That makes me think that the signal is getting there but maybe not consistently? I hadn't changed anything between cranking like moving wires or anything, just pausing for a minute then cranking again.

I really do appreciate all the help and knowledge sharing, I'm generally pretty good at troubleshooting but this one is quite a treat. Would it be worth throwing a hundred bucks at an oscilloscope at this point?

 

Okay, I'm convinced your connections were good. so no signal to the pcm. Good. Now check for it directly at the sensors. That's the next step, you're almost there...keep going.

 

Alright, I'll try at the sensors tomorrow and report back.

Anticipating the two results - if I do get signal directly at the sensors, the next step is working from the sensor to the PCM connector and finding the breakdown? If I don't get signal at the sensor(s), I assume that would mean a faulty sensor. They're both brand new from the Ford dealer but it wouldn't be the first time I've had a bad sensor out of the box.

 

And no, you won't need a scope to verify the no signal. If it was there it would have showed up on the meter. A craftsman meter is just as accurate as my $800 fluke as far as voltage goes. I've tested that before out of curiosity, they read identical voltage values. It's the other readings that make the fluke expensive. Scopes are sweet, I have no idea how I got by without it for so long, but a scope just for this? Not unless you want one, but you definitely don't need one. A few hundred bucks would be a seriously outdated scope by the way...but those work too. Not a knock on old scopes.

 

You got it. And it's a lot easier to find the bad wires than you think, but we'll get to that later.

Now, bad parts right out of the box....yes that can and does happen, and is not even rare with some parts, cough cough, dorman. But OEM parts? Sure it can happen, but I've never seen it. Not yet anyways.

 

Great. If a bad wire happens to be the case, would it be a full harness replacement or would it be possible to just replace the bad wire(s)?

Glad I started this thread because I was at a dead end and not finding any threads or information in general on a no start with these conditions.

 

Not the whole harness, just repair the bad wires. It's going to be in a location where there is heat, or vibration. Most likely where there is a shield or something that it will be rubbing up against. Also, it's going to be in a location where it affects more than one circuit. So it would have to be in a spot after the cam and crank sensor wires come together. Any spot from the pcm connector to where the sensor wires split and go separate paths, and usually where they route along something hot or against something metal that they can rub against. Make sense?

You can cut the harness open from the pcm connector to where they split and you'll probably find it, but it's much easier to start at the sensor and chase the signal. You'll need to pierce the wires for this, but that's no biggie, just use nail polish to seal the holes when your done.

Either way, do not skip the part where you verify there is signal at both of the sensors. We can be pretty confident that it's there....check it anyways. The waste of time is to great for being wrong.

 

Indeed, that all makes sense.

Certainly not wanting to jump ahead on this. Just getting an idea of the possible scenarios given the results and if our timelines don't line up tomorrow after reporting back, I'd like to have a direction to go.

 

Roger. You'll do fine. Just find the signal and chase it back until you don't see it anymore. Then cut open the harness between where ya had it and lost it and Viola! Fix.

 

Quick update, I was able to probe at the cam sensor connector. Confirmed connections again with the resistance and readjusted the probes several times to be sure.

I did not get any change in the multimeter. It sat at 0 both hand cranking at the alt (confirmed crank is turning) and bumping the key. Brand new sensor.

The crank sensor is a bit more tricky to get at so I am doing that now and will report back.

I have the volt meter turned to 200 Vac, as low as it goes for ac.