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Discussion Starter · #1 ·
I have a 2012 Nissan Altima 2.5 S and I have a check engine light and I’m getting code P0500 which it says is for vehicle speed sensor A. I replaced vehicle speed sensor A and reset my codes but the P0500 code just came right back.
my question is; could this code be from one of the other vehicle/wheel speed sensor and if so is there a way to check them so that I’m not just changing parts all Willynilly. I have heard alot of bad things about these CVT transmission and it has me scared that there could be a problem with my transmission. Especially after already changing the sensor.
Any help would be greatly appreciated.
 

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Is the DTC showing up in the engine, transmission, or both? If it's only in the ECM then it's possible an ABS error like a bad wheel sensor could cause it, but you should also be seeing ABS and slip lamps. If it's in both then the sensor in the tranny is responsible. You could have a bad one, or it's possible you replaced the wrong one. The VSS sensor (also called Secondary Speed) is on the back of the tranny, the one on the top rear is the Primary and the one in front is the Turbine.
 

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Discussion Starter · #3 ·
I replaced the one on the top rear. My speedometer works fine. I don’t have any other lights. Not ABS or anything just the P0500. Also the cruise control doesn’t work.
 

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The VSS sensor (also called Secondary Speed) is on the back of the tranny, the one on the top rear is the Primary and the one in front is the Turbine.
That was for a '13-up, my bad. The '12-down had only Primary and Secondary, and it sounds like you replaced the right one.

I replaced the one on the top rear. My speedometer works fine. I don’t have any other lights. Not ABS or anything just the P0500. Also the cruise control doesn’t work.
The cluster gets speed info from both the TCM and ABS, so the fact that the speedo works doesn't tell you anything about the sensors. However, since there's no ABS or slip light then it's doubtful the ABS has any problem, and chances are that would also cause a P1574 in the ECM (see below). So it sounds like you either got a bad replacement sensor or there's a problem in the wiring. There should be 12V at the Brown wire on the connector and ground on White, the signal is on Purple. However, if it's wiring, it's odd that you're not also seeing a P0720 in the TCM. Is your scanner able to read the TCM and ABS along with the engine, or only the ECM? If it can only read the ECM then you may need to find a better scanner.

Here's a good explanation of the system from a 3rd-party source. "ASCD" refers to the Cruise Control:

The Engine Control Module (ECM) receives two vehicle speed signals via Controller Area Network (CAN) communication line. One is sent from combination meter, and the other is from Transmission Control Module (TCM). The ECM uses these signals for ASCD control. Code P1574 will set if the ECM detects a difference between two vehicle speed signals is out of the specified range. The Wheel Speed Sensors (WSS) input to the Antilock Brake System (ABS) actuator and electric control unit. The ABS actuator and electric control unit communicates vehicle speed to the combination meter (instrument cluster) on CAN for speedometer operation. The combination meter communicates VSS to the ECM on CAN. The secondary speed sensor detects the revolution of the Continuously Variable Transmission (CVT) output shaft and emits a pulse signal. The pulse signal is transmitted to the TCM, which converts it into vehicle speed.
 

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Discussion Starter · #5 ·
So, I was able to use a buddy of mines scanner( he is a mechanic). The codes that showed up were in the engine and they were P0500 and P1574. I haven’t done much research yet but I’m going to pull the air box and check the sensor how you said and then get back to you with the results. But it was just like you said, with a better scanner I was able to read codes that weren’t evident before. Thanks.
 

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P1574 is just the ECM saying there's a conflict in the reported ABS speed versus the reported TCM (transmission) speed. It still indicates one of the two speed readings is wrong. I have to think you got a bad VSS or there's a problem with the VSS wiring. See if your scanner will stream the vehicle speed from the TCM and ABS for comparison.
 

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Discussion Starter · #7 ·
So, I was able to use my buddy’s scanner to stream the data. I couldn’t compare them but I did stream both sets of data and it basically matched up with the speedometer. I was even able to engage the cruise control at lower speeds. Once I got past 60 I couldn’t. But it showed all of the speed sensors as working. Do you still think that it could be a shorted wire? I just haven’t had time to take the air box off yet to look at the wires. Once again, I appreciate all of your help.
 

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No, since it reads at lower speeds and breaks up above 60, I'd say most likely you got a bum replacement VSS. They're Hall Effect types just like your crank and cam sensors, and you'll find dozens of posts in here about people pulling their hair out over bad aftermarket replacements. Even an OE sensor can go bad if it's dropped prior to installation, dropping a Hall can de-magnetize the internals.
 

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When I was doing the live data streaming I did notice that at idle the speed sensor read 14.55 mph when the car was in park. Does that affect it at all?
It certainly, could, yes. If I recall correctly, the difference that will trigger a P1574 is about 5mph. The only ways a reading like that can happen are a bad sensor that's responding to EMF from other systems in the car, electrical crosstalk in the wiring, or having the Output sensor connector swapped with the Input or Turbine sensor. The latter is an easy mistake when changing the trans on a gen5, but I'm not sure it's even possible on a gen4. The other two are certainly plausible. Zero should read zero, not 14.55.
 
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