My speedometer on my g35 x sedan awd works when I test the gauges but when it comes to showing movement with speed it’s stuck at zero I changed 3 of my 4 wheel sensors I’m waiting for the last one but I’d think I’d have some sort of movement but I don’t know does anyone have any ideas

 

The rear sensors are the ones that the speedo is based on.

Wheel speed sensor data goes to the VDC/TCS/ABS computer, that computer puts the speedometer signal into CANBUS and the instrument cluster reads the CANBUS data to display speed.

If you have other things like the tachometer that are working then it's not a CANBUS issue since tach is using it as well, in that case it's probably a failed instrument cluster. Test mode on the dash just ensures that all the needles can move and is a reference point for disassembling the cluster so you can put the needles back in the correct position.

Typically when you lose a wheel speed sensor you immediately get a VDC/TCS/ABS error on the dash.

 

I do have a VDc light I. I. My dash the front left wheel sensor is the only one I have not changed but I also bought one of those speedometer that plug into your. Car plug under the driver wheel and is does not show speed either I’m think it’s the speed sensor in the rear defarantal I think that where it is

 

Call around and find someone with an OBD2 scanner that does ABS codes and find out why that light is on, most parts houses will scan your car for free since they want to sell you stuff. That way you can stop randomly throwing parts at the car and instead focus on listening to what the car is telling you is the problem.

It will be a code that starts with the letter C.

Also look at the differential and see if those sensors are damaged, or the wiring.

 

so I was there today I got my last right hand sensor brand new there all brand new. Now still no movement i
going to buy a good scanner to see what is going on do u have any recommendations ? I appreciate all ur help
but it has to be the speed sensor or dashboard the sensor i the rear Deferential

 

No it doesn't have to be, you're assuming it's the sensor and not the ABS/TCS/VDC computer that translates it into CANBUS for the dash to read, or the wiring between the two.

The only thing you have verified is it's probably not the instrument cluster since you said you read OBD2 speed data and it showed zero. That means the ABS/TCS/VDC computer is either not receiving data or not translating it to CANBUS. You should verify that plug in speedometer actually works though by testing it on another vehicle.

My recommendation is to drive down to a Napa, O'Reilly, Autozone, etc. Have them scan the car for free and tell you what code it's throwing, you know it's throwing a code since the dash light is on.

 

p1721 I got as the code

 

Ok that code is basically "the dash isn't sending speed data via CANBUS to the TCM so the TCM threw that code".

The next step is the verify the wire harness between the VDC/ABS/TCS and the rear wheel speed sensors are still good.

Disconnect the battery, unplug the TCS/ABS/VDC harness, unplug the rear wheel speed sensor harness. Make some kind of extension lead (usually just poking some length of 14AWG stranded wire into the wire harness to make contact with the pin works) because the leads on your multimeter won't be long enough and you need to extend the circuits one at a time up to your meter.

Use a digital multimeter, measure resistance across each of the circuits, you should have the same reading as if you were touching the meter probes together (usually 0 or 1 ohm, indicating a complete/closed circuit)

Measure each of the 4 wires separately,

TCM harness is M93, wheel speed sensor harness is B113

M93 pin 11 to B113 pin 2, black/red stripe wire
M93 pin 12 to B113 pin 1, brown wire
M93 pin 13 to B113 pin 4, pink wire at M93, purple wire at B113
M93 pin 14 to B113 pin 3, orange wire

 

I would also verify IPDM fuse 82 is still good but you would likely have more lights on the dash if the TCS/ABS/VDC computer wasn't powered up.

Unfortunately there isn't a non Consult-II self-check for that computer so the only way to verify it's actually working is a trip to Nissan/Infiniti for a 1 hour diagnostic.

 

so do u think it could b the dash

 

added the new speed sensor in the trans no luck could it be the abs thats doin it cause the lights always on so is the vdc off

 

Personally I would just schedule a 1 hour diagnostic at Nissan/Infiniti. The Consult II/III dealership tool will narrow down the issue VERY quickly.

Are you sure the scan tool last used was capable of doing ABS/TCS codes? Because you posted a TRANSMISSION code, not the C#### code that's causing your light to be on.

Can't just use a regular OBD2 scanner, this isn't a powertrain code you're looking for.

 

should i still tr this