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Discussion Starter · #1 ·
Car runs fine without the sensor plugged in but when it's plugged in it will not start, it turns over catches and dies immediately.

how far do I have the cut back the wires to check? All the way through the wiring harness or just the wires that come off the harness and into the camshaft sensor?
 

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That sounds like a bad sensor and not a wiring issue. When a CMP or CKP malfunctions but doesn't go "flatline," it will cause no-starts because the ECM is confused about when to fire the plugs and injectors. Disconnecting the bad sensor flatlines it and allows the ECM to run using the remaining good crank or cam sensor without being confused.
 

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Discussion Starter · #3 · (Edited)
I have recently purchased 3, 2 aftermarket and 1 oem camshaft sensor and they all have done the same thing though (there's no way all 3 were bad out of the box, could there be?). And I did recently just install a new oem crank sensor. It's really becoming a money Pitt. Could the reluctor ring just be so full of crap it's confusing the sensor while its trying to do its job?

or more so, could the ring be damaged? The car seems to run fine without any weird sounds so I assume pieces of metals aren't flying aroundin there.
 

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or more so, could the ring be damaged? The car seems to run fine without any weird sounds so I assume pieces of metals aren't flying around in there.
The cam reluctor on an MR is machined into the end of the camshaft, so you'd be in big trouble if that was the problem. It is possible you have some magnetic crud built up on the reluctor teeth (or on the tip of the sensor) that's preventing proper triggering, but that's easy to check for and clean up by removing the sensor and bumping or hand-turning the engine. The most likely answer is just a sensor that's getting weak.
 

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Discussion Starter · #5 ·
But I've tried 3 different sensors and they all acted the same, even oem camshaft one from Nissan. So if the ring isn't dirty i dont know what to do next. I don't really want to buy another new oem CMP when I just got the Nissan one..
 

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Discussion Starter · #7 · (Edited)
there not in order but is the correct way? On the first picture when it says to check voltage am I grounding anywhere or somewhere specific? I'll do the testing but when I put the sea-foam into the crankcase I noticed it seemed to want to start a little easier, possibly it was cleaning the Ring? Lol who knows I'm at loss now.

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You'll need some safety pins for back-probing the connectors, the way the ESM tells you to check it is incomplete. They also don't mention anything about pin-fit, and that's something you can also check with an 0.025" diameter safety pin. You may end up needing that since the sensor is probably falsing and not dead, but start with any old pins and we'll see if you need a specific one.
1) Check voltage between G/Y and BR with the sensor disconnected and the key on. You should see right around 5V. If not, check from G/Y to the battery ground. If you get 5V from the battery ground, but 0V when using the the BR wire, then BR is broken. If both grounds give you a 0V reading then G/Y is broken.
2) Check voltage on R with the sensor disconnected. You should also see 5V there, but the voltage is coming through a pullup resistor in the ECM and not from the 5V supply (AVCC). If you see 0V then either R is broken or there's a problem in the ECM.
3) If steps 1~2 check out, back-probe G/Y and BR with the sensor plugged in but removed from the valve cover. Repeat step 1 but using the back-probes, keeping the sensor away from metal. If G/Y reads much lower then you have resistance in the G/Y wire. If BR reads much above 0V then you have resistance in the BR wire. If R reads lower then it's a bad sensor, new or not. Resistance on G/Y or BR can be in the wire or at the ECM connector pins, so that's where pin-fits come in.
See what you find, and if 1~3 don't reveal anything, I'll show you how to remove the backshell from the ECM connector so you can check there.
 

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Discussion Starter · #10 ·
First 2 steps I got right around 5v. I'm confused on the second part.

I have the pins in the GY and BR and the key ON, I touching the GY one with the BR or the ground?
And what about the BR one, am I using that pin in that one and touching the ground?

Sorry I need to work on my wiring diagnostic skills
 

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You're back-probing both wires with the sensor connected, so the sensor is drawing operating current the way it would with the engine running. Voltage doesn't always tell you anything unless current is flowing. Here's what a "back-probe" means:
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You're sliding the safety pin in between the rubber and the wire to make contact with the pin without removing the connector. When you repeat steps 1~2, you'll be touching the safety pins instead of the connector pin. I.e., for the first part, you'll touch the safety pin on G/Y with the red meter probe and the safety pin on BR with the black meter probe. Since current is flowing with the sensor connected, if the readings are different from what you measured when disconnected, it means there's resistance in the circuit. That's known as a "voltage drop" test.
 

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The G/Y and BR should read the same connected or disconnected, if they differ by more than about 30 millivolts (0.03V) then there's a resistance issue. The Red wire may be a bit lower depending how much the sensor leaks, but it shouldn't be lower by a lot with the sensor away from metal. The way that works, the sensor has an internal transistor that "overpowers" the pullup resistor in the ECM whenever it sees metal pass by, pulling the signal line to ground. Unfortunately the sensors are very precise and also directional, otherwise you could check them just by waving a metal tool in the vicinity of the tip. That doesn't usually work with the type of Hall sensors Nissan uses.
 

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Discussion Starter · #14 · (Edited)
I will do the testing today. Just FYI i'm not a big fan of wiring, it's confuses me. Replacing parts and test other misc parts is easy for me but having to do in depth is like a run a round for me.

I just watched a video with a guy doing a 3 connector cam sensor test, he plugged it in outside of the car and and back probed the GROUND and signal wire and started cranking the car, is this correct?
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I really appreciate your time doing this and explaining everything, not just laughing. I was never taught to do much wiring so I'm learning right now lol.

There is another thing that confuses me. Even if it has issues starting cold If say I do get it up to normal temp and drive around I can shut it off and it will restart perfectly, with the same connector plug into the sensor?
 

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That test will tell you if the sensor is working, but not whether it's working well or half-a$$. To answer your second question, it isn't uncommon for Hall sensors of any type to be temperature-sensitive. I've seen ones that worked cold and no-started warm, and others that worked warm but no-started cold. Sometimes the mechanical clearances warm/cold contribute to that, since all Halls are very sensitive to the gap between the sensor and the teeth. And of course everyone has heard some nightmare story about wiring that's broken internally and only loses contact when hot or cold, and that can truly be a nightmare. If you think temperature is a factor, one way to find out is the test in the video performed both cold and warm. The sensor output voltage should show little or no change.
 

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Discussion Starter · #16 · (Edited)
Edit: I did the accelerator pedal release and the throetlttlw body set by doing key on and off for multiple seconds following the video.
So I was just out messing around with it. It cranks and catches and dies, but then I can try again and it almost dies and I catch it with the gas pedal feathering it and it revs up to 2-3k and the settles down normal. Should I do the Throtfls body relearn and accelerator pedal procedure for sh*ts and giggles?
But once it does get running it sounds perfect, runs great sounds good, throttle response is good. Could the electronic TB be out of whack maybe needing a relearn?

Oh man, I really hope there's no broken wire hidden in the harness :(

Is it possible to clean the reluctor ring with like a Qtip or something?

i have one more oem Nissan CMP on the way, and I pray that fixes it because I'm not liking this car very much right now lol!

Thank you so much for trying to help me, and I'm sorry if I'm frustrating you with this. I'm an extremely big dummy when it comes to wires and testing
 

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So I was just out messing around with it. It cranks and catches and dies, but then I can try again and it almost dies and I catch it with the gas pedal feathering it and it revs up to 2-3k and the settles down normal. Should I do the Throtfls body relearn and accelerator pedal procedure for sh*ts and giggles?
And an IAVL, yes. IAVL will be the important one, that's what calibrates the MAF and synchronizes the MAF with the TPS. It certainly can't hurt.
 

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Discussion Starter · #18 ·
Yup, I just did both of those. The car is at operating temp now. When it cools down I'll go out and try to start it. And I do have another oem CMP on the way as well I'll install when I get it. I know it's a broken record but I can't thank you enough for giving me tips.

I'll post back if it's still doing the issues later.
 

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Discussion Starter · #19 · (Edited)
I did the IAVL and no luck. Still same thing.

how do I disconnect the ecm harness connector? It says to check continuity between terminal 2 (on the sensor itself?) and ECM terminal 63.

-continuity should exist it says.

then check terminal 3 to ECM terminal 65 and same thing.

-continuity should exist. If it doesn't that means there's a break somewhere in the wire right?

I'm confused what it means by checking harness for short to ground and short to power. If all checks out it says to:
Check and remove any debris from signal plate( reluctor ring). How would I do that without having to rip the whole cylinder head off I don't have a place to really work on it, beside my apartment parking lot and they're already giving me the bug eye for doing what I'm doing.
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A fishing magnet through the sensor hole works fine for capturing metal debris on the reluctor. Anything that isn't metal isn't a worry.

Checking for shorts to ground or power involves taking both ends of the wire loose and ohming to battery+ and battery-. With both ends loose, if the reading isn't infinity (or at least megohms) then there's an insulation failure inside the harness. Where wires run in a bundle like the 3 conductors on your cam sensor, it's also a good idea to ohm each of the wires to one another.

Here's how you get the connector at the ECM loose and remove the backshell. These pics are of a TCM connector, but the ones on your ECM will be the same sort:
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