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Mike V.
Mike V., Nissan Technician
Category: Nissan
Satisfied Customers: 20465
Experience:  Nissan factory trained and Certified Subaru Technician.
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2002 NISSAN ALTIMA: SPEED SENSOR..I HAVE TO REPLACES THE SENSOR

Customer Question

I HAVE A CODE PO725 ON A 2002 NISSAN ALTIMA SPEED SENSOR IMPUT MALFUCTION DO I HAVE TO REPLACES THE SENSOR
Submitted: 4 years ago.
Category: Nissan
Expert:  Mike V. replied 4 years ago.

GreetingsCustomerand welcome to JA! I will do my very best to assist you with your problem.

You have to replace the crank sensor to resolve this issue. Normally you get a crank sensor code as well. Normally the crank sensor will resolve the issue.

If this is the 2.5L, the sensor is located in the back of the engine along side the rear engine mount on the drivers side. This is where the transmission and engine meet.

Hope this helps!

Mike V., Nissan Technician
Category: Nissan
Satisfied Customers: 20465
Experience: Nissan factory trained and Certified Subaru Technician.
Mike V. and 7 other Nissan Specialists are ready to help you
Customer: replied 4 years ago.
well i replaced the crank sensor It woked for about 3 hr then it came back on .Now what do i do?
Expert:  Mike V. replied 4 years ago.
Same code? Do you have a volt meter so we can test the wiring?That has to be the next step.
Customer: replied 4 years ago.
yea i have to find it but i dont have the car here.. The wife got it at work . I wont have axcess to it at 6:00pm mountain standard time.Then i will be able to worke on it.
Expert:  Mike V. replied 4 years ago.
OK, let me know and we can check out the wiring and see what is going on. Seems if it worked for 3 hours it should work.
Customer: replied 4 years ago.
ok when i get the car i will let u know.
Expert:  Mike V. replied 4 years ago.

k,If I am not on,leave a post so I know you are ready...I do stop to eat!

 

Customer: replied 4 years ago.

I will leave u a post.Oh by the way thanks alot

Expert:  Mike V. replied 4 years ago.
You are very welcome!
Customer: replied 4 years ago.

I am ready when u are

Expert:  Mike V. replied 4 years ago.
OK,I am back, you do have a volt meter?
Customer: replied 4 years ago.

yes

 

Expert:  Mike V. replied 4 years ago.
Alright, get ready, you are going to have to disconnect the transmission control module and the ecm and check the wire from one to the other. Seems the ecm is seeing the engine speed,but the tcm is not.
This means there is either an issue with the wire to the tcm or the ecm is not sending the signal.The ECM is located behind the glove box. The TCM is right next to it.
Now,I am going to send you wiring diagrams as we go through this and I will tell you how to rear them and what we are looking for. Here is a diagram of the tcm/ecm location. Let me know when you have them disconnected. You should also disconnect the battery before starting.
graphic
Expert:  Mike V. replied 4 years ago.
Actually before you go digging, First, check and make sure the green tab popped back out on the crank sensor when you installed it. Plus, is it an aftermarket sensor or a nissan factory part?
Customer: replied 4 years ago.
ok i have unpluged 3 pluges one long one and two short one
Expert:  Mike V. replied 4 years ago.
OK, you are looking for a white wire with a green stripe. I have 2 diagrams for you the large one is the ecm, larger connector and the small one is the tcm. In these views,you are looking at the end of the harness that plugs into each components. You need to ohm them and make sure there is resistance.
I have highlighted the terminals you need to graphic
graphicohm.
Customer: replied 4 years ago.
which one do i test the white or the gray to the tcm
Expert:  Mike V. replied 4 years ago.
You should see one that is white with a grey stripe. It will also be the same color in the ecm harness
Make sure you recheck the connector on the sensor to, if the tab isn't all the way out, it could be the problem.
Expert:  Mike V. replied 4 years ago.
I have to call it a night here. Please post your results and I will get back to you in the morning.
Customer: replied 4 years ago.
well on 20 k i get a reading 1945 in thoes sloutsthen it go to 1
Expert:  Mike V. replied 4 years ago.
OK, this tells me that there is continuity. This means the wire is good. I would recheck the connector and make sure it is tight at the sensor.I have a had a few that were difficult to re lock. Also, if you didn't use a factory sensor, you might want to go that route. Otherwise there has to be some type of problem with the ecm sending the signal to the tcm. You really need a scan tool to determine if that is happening.One that can watch the engine speed through the tcm.
Customer: replied 4 years ago.

 

 

 

Hello just got home from work . I have a scan tool it gives freeze frame data and everything. that how i know it had a code of po725 and po335

 

 

 

 

 

 

 

 

 

Expert:  Mike V. replied 4 years ago.

Welcome back, so it did have the P0335 as well. So on your tool can you see the engine rpms when the car is running on it?

 

Customer: replied 4 years ago.
yes it does but i dont remember seeing any speed rpm on it but the temputure on it was 185
Expert:  Mike V. replied 4 years ago.

OK, well, I think wither the sensor is not cutting it or there is some kind of wiring issue to the ecm. You should see engine speed on the scan tool. If it is capable of live readings, no rpms would mean no crank signal. So, when you can check it out.

Also, really check the connector as they can be a pain to get back on tight.

I have also seen the pins pullout of the old sensor and get stuck in the harness.So if you still have the old sensor,make sure all of the pins are still in it and not stuck in the wiring.

Customer: replied 4 years ago.
i just tried the scaner and i couldnt get any rpm out of it
Expert:  Mike V. replied 4 years ago.

/As in it is not an option on the scanner or it is not showing up

 

Customer: replied 4 years ago.
well when i put the scanner on it gives five codes 2 725 and 3 po335
Expert:  Mike V. replied 4 years ago.

ok, so this is a code reader not a scanner.

I suspect we are going to have to go with a nissan crank sensor and recheck the connectors.

If you don't have the car back together yet inside we can use the volt meter to check some wire still to.

At the crank sensor we can check for power and ground, then if you have them we can check for continuity on the sensor signal wire.

Should have battery voltage on the Red/Green wire and continuity to ground on the Black wire

Customer: replied 4 years ago.
I have hook up the emc and the tcm but i havent put the glove box back on yet.I can go buy a senser from the dealer well u let me know what to check for. oh I have a obd11 auto scanner
Expert:  Mike V. replied 4 years ago.

Well, this is what you need to check at the sensor end. I will send along another digram like I did last night for checking the signal wire

At the crank sensor we can check for power and ground, then if you have them we can check for continuity on the sensor signal wire.

Should have battery voltage on the Red/Green wire and continuity to ground on the Black wire

Customer: replied 4 years ago.
my battert voltage is 12.76 on the red/green wire it is 12.17. on the black wire i have continuity to ground
Customer: replied 4 years ago.

can u check for continuity on the senser

Expert:  Mike V. replied 4 years ago.

Sorry to leave you hanging man! wife just got home from work,

here graphicis the sensor test

 

Customer: replied 4 years ago.
that all right .wife had to use the car any way.Had to go watch the grandbaby..so i wasnt able to go get the senser.so tommorow i will send the wife to go get it . but i have to work in the mornning .I dont get out till 2:30 so have a good night. oh by the way what did u mean by the green tab pop back out on the sensor
Expert:  Mike V. replied 4 years ago.
OK, we will hook up tomorrow then. Yes, the green tab that you have to push in to disconnect the sensor.It has to pop back out in order to lock the harness back onto the sensor. I have has several that didn't want to
Customer: replied 4 years ago.

hello I dont think i have a green tab my disconect from the senser is black .but any way i dont have time to work on it today. i have my grandchildern her from out of town .there here for my other grandchild birthday tomorrow.so in joy your weekend.well i check the code again and now it say pi340 camshaft sensor

Expert:  Mike V. replied 4 years ago.
No problem! Let me know when you are ready to resume! Enjoy the kids!
Customer: replied 4 years ago.
now i have to go buy a camshaft sensor.because i have a code po340
Expert:  Mike V. replied 4 years ago.
So, it is no longer the codes for the crank sensor?
Customer: replied 4 years ago.
right .it can on when i scaned it againl on 1 code now po340. now it wont start at all.
Expert:  Mike V. replied 4 years ago.

yeah, won't start with a bad cam sensor. It is safety to keep the car from having the valves and pistons hit. It can't tell where the timing is without the cam sensor. Here is the location of that one. Same type of connector on it.

graphic

Customer: replied 4 years ago.
well that is the one that i bought at the parts store .that said it was a crankshaft senser. can u send me a picture of where the crankshaft sensor is.
Expert:  Mike V. replied 4 years ago.

Here is the picture. This is the rear engine mount and the crank sensor is right next to it. This is the view from the back side of the engine

graphic

Customer: replied 4 years ago.
no wonder we we were not getting any place because they. sold me the wrong part
Expert:  Mike V. replied 4 years ago.
Yes,it certainly makes everything a lot clearer doesn't it?
I think it is still best to get it from the dealer. This is constantly updated because it is a problem on these cars.So if you get it from the dealer, it will be the most up to date part.
Customer: replied 4 years ago.
yea i guess i will . i have the receipt that says it is a crank shaft sensor
Expert:  Mike V. replied 4 years ago.

right, but did you install it in the back side of the engine or in the head?

 

Customer: replied 4 years ago.
in the head next to the water pump. that why i couldnt find the green tab u were talking about
Expert:  Mike V. replied 4 years ago.
ok, so, take the sensor out and install it in the back of the engine block. If you have the other sensor you took out, put it back into the head and the car should be fixed. The crank sensor is a real bear to get to. It all makes perfect sense now.
Customer: replied 4 years ago.
yea i will but i still think that i need a crankshaft sensor
Expert:  Mike V. replied 4 years ago.
you may, but it sounds like they gave you the crank sensor and it was just installed in the wrong location.
Customer: replied 4 years ago.
are the both built the same or are the different in shape .because this one is straight just like the one i took out
Expert:  Mike V. replied 4 years ago.

They look identical, but read differently

 

Customer: replied 4 years ago.
ok thanks .and good night i will go to the dealer and get the crank sensor
Expert:  Mike V. replied 4 years ago.
OK, you have a good night and let me know how you make out!
Customer: replied 4 years ago.

well i took the car in because i couldnt reach the sensor .but that was the problem.thank u for all your help.

Expert:  Mike V. replied 4 years ago.
You are very welcome! I know it is a nightmare to get to....at least it always has been for me.The small guys don't have to much trouble.Really sorry that you had to take it in though
Customer: replied 4 years ago.
ok i have a different problem with my car a different code .How do i pay u for this information
Expert:  Mike V. replied 4 years ago.
You have 2 options, you can open another post or we can continue here. It is probably better if you start a new post however. If you put for carguy1 in the beginning of the post,I will get it and we can go on. Thanks!

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