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G37 crank position sensor issues

Old 03-25-2019, 09:12 PM
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Boostindom
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G37 crank position sensor issues

I hope Iím in the right place Iím the proud owner of a 2011 ipl 6mt as well as a 2003 g35 with the sport package. I love them both and have been building g cars along time. The ipl is throwing a po335 cps code I ordered a new oem one from Nissan and it is worse. Before it was running perfect but in safety mode not going over 3k rpms. Now I changed it and it throws the code immediately when it was after some driving and now the rpms flutter rapidly between 1100-1500 not sure where to go from here. I know it could be the pickup or the harness but why would it get worse with a new oem sensor? You guys may have some insight that I donít. Thanks in advance
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Old 03-25-2019, 09:14 PM
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Codes thrown after new part?
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Old 03-25-2019, 09:47 PM
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Yeah

Originally Posted by slartibartfast View Post
Codes thrown after new part?
p0335 immediately upon start up with the triangle with an ! In it
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Old 04-01-2019, 08:03 AM
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Both the old and new sensors ohm out at the same range

I started troubleshooting wiring between the connector that feeds the ckp and the ecu terminals. Oddly enough I have no continuity between the sensors signal wire and ecu terminal 37 which I should have. I have a good ground (terminal 2) a good power source (terminal 1) with continuity between both and there respective ecu terminals (46&47) Now where it gets weird is I have 5 volts with the ignition on, on terminal 1 & 3. I would think I should only have 5 volts on 1 being the constant power supply but terminal 3 should only read when the ckp is installed and engine is running, am I correct? I donít want to hack apart the harness until I am definitely correct on diagnosis as it is tight under there and may require removal of large mechanical parts. Havenít got many responses here but maybe more info from me helps. Thanks in advance from all of you
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Old 04-20-2019, 06:15 AM
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No one knows anything?

Surprised with no answer am I posting in the wrong place?
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Old 04-20-2019, 09:21 AM
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ILM-NC G37S
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With the harness disconnected at the CKP, you should only have voltage at Pin 1 (5V). If you have voltage at Pin 3 (signal) then you either have a shorted wire or a problem with the ECU. Pin 3 should only have voltage when the harness is attached to the sensor and the engine is running UNLESS it is a bad sensor which is unlikely as you mentioned it is new.

If possible, at the ECU and with the harness disconnected at the CKP, check pin 37 and see if there is voltage. If there is that's your problem. Pin 37 is INPUT only so it should not be supplying voltage only reading a voltage signal. Also, check pin 128 for ground. If all checks out then you might have a wire issue.
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Old 04-21-2019, 07:16 AM
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Thanks for the response

Thatís a huge help, Iíve doubled back on it checking and rechecking and have other oddities. Terminal 1 has continuity with 47 not 46, it is a ground but when you turn the ignition on it gets 5 volts. Terminal 2 has continuity with 46 but doesnít get any voltage. So it seems continuity wise they have switched but not functioning with the ignition on. Itís hard for me to wrap my head around that. I have to pull the harness out and do a process of elimination. Iíve been swamped but thatís the next step. I donít think itís the ecu because of all the crazy continuity issues. Again thanks for your time and help.
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Old 04-21-2019, 09:27 AM
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We are all here to help. If both ends of the harness are disconnected (CKP, ECM), and you have continuity crossing over wires, then the issue is with the harness. Could be a chafed wire or some other gremlin. No way should ECM46 be continuous with CKP2 (nor ECM47 w/ CKP1). Based on the FSM, the likely culprit is the harness at this point. Nothing in the FSM points to the ECU. Remember, this is with the harness completely disconnected at the CKP and the ECM!

Keep us updated, pls. Will help any way I can...
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Old 04-21-2019, 06:36 PM
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Yeah I think itís the harness

Iím hoping to get out there and pull the harness through the firewall in the next few days to visually inspect it, I have to get the hat off the ecu connector too so I can jump new wires from 46,47 & 37 and see how she runs. There any tricks to removing just the plastic hat?, also any other junctions between the ecu and ckp? I know my g35 does. Thanks again your a lifesaver. What part of NC?
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Old 04-21-2019, 09:27 PM
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It is going to be a real PITA to say the least. Is there no way you can check the continuity of the existing wires without running new ones? No advice re: the plastic hat.

Per the FSM, the wires are a straight shot from the CKP (connector F2) to the ECU (connector F101). Keep in mind my FSM is for 2008.

I am outside Wilmington- southeastern part of the state on the coast. Been here over 30 years and absolutely hate it here but that's another story. Good luck!

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Old 04-22-2019, 08:00 AM
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Iím sure it will be

I have continuity but they are wrong 1-47, 2-46, none on 3-37, so I figured the easiest way to see if itís the harness is bypass it running new temporary wires. I can run them out the door if the ecu is still in the car or if Iíve already removed it Iíll do it in the engine bay. Then I can test the car, if it works out Iíll rewrite it and tuck it inside the loom factory fresh. I just want it repaired so I enjoy the car, gonna boost it but have to get this gremlin off my back first. Iím moving to NC in a few years but up in the mountains by Asheville. Also I have a 2011 FSM itís the same as yours. Thanks again I will keep you updated when I can get out to work on it
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Old 04-22-2019, 09:18 AM
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Gotcha. Sounds like you have a good plan on order. Lots of luck banishing that gremlin. As a side note, you will love Asheville. It is a entirely different world compared to the hell my area is.
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Old 05-15-2019, 01:01 PM
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Figured it out

The car doesnít have a ckp problem it is the signal plate connected to the flywheel. I continued troubleshooting electrical wiring and removed the hat on the ecu connector thus realizing the fsm diagram is numbered from the top view, surprising but then realized I had continuity. Knowing it wasn't the sensor and knowing the clutch was replaced 10k ago and then the ckp 8k ago I figured maybe the clutch being destroyed effected the flywheel. I used an endoscope and hand rotated the engine to create a video I could inspect. The teeth are damaged on the signal plate thus preventing an accurate reading at higher rpms. Here is a few pics of bad teeth. Hope this helps someone if they ever end up in my boat.

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The following 2 users liked this post by Boostindom:
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