(Sticky/General Maintenance Reference Links maybe?)

This post is just to help out anyone else who has a faulty speed sensor.

My speedometer has been on the fritz for months. At first it was intermittent, then it stopped working altogether.

I followed the instructions to test the speed sensor in the service manual which said to test for the presence of an AC voltage on the sensor outputs when the pinion is rotated. The test was "good" (see below), and so I went on to replace the instrument cluster and check the wiring, all of which didn't do anything to fix the problem.

Finally I picked up an automatic version of the speed sensor (didn't know they were different), which I spun by hand while it was plugged in to the car, and lo and behold the speedometer started working. But of course, it was the wrong sensor model.

So then I purchased a used sensor from a user here, which arrived and worked, but only for a few days.

Then I started to get irritated. I disassembled both the original sensor and the automatic sensor using a dremel tool. Once I cut though the external metal housing 1/4" from the bolt ring, the two pieces just slid apart.. 1/2 was the pinion attached to a magnet, the other half was the hall sensor body. I took the rear half from the automatic sensor and stuck it on the front half from the manual sensor, and... it worked! But of course, it was cut in half. Maybe I could use some gasket material and stick them together?

Then I was comparing my Frankenstein sensor to the used sensor I got from Maxima Junkie. I noticed the the rubber piece in the back of the used sensor was sticking out an extra 1/4", which meant the hall sensor housing was not fully in place against the magnet! I pushed the black rubber back in, and presto -- it started working again.

It turns out that the rear of the sensor was simply a little too far away from the magnets to generate a sufficient voltage to run the speedometer, but was large enough to fool me in to thinking the sensor was good at first.

If you need to do this, I recommend cleaning everything up and applying a little coat of gasket material to hold it in place, or rigging up some other method of holding the rear rubber parts in place once you put it back. Otherwise it will probably just come apart again. The rubber back should be flush with the metal housing.

The sensor is actually so simple that unless the gear has been destroyed, this is probably what is wrong with your sensor if it is not working. I'm guessing nearly every faulty speed sensor not obviously physically damaged is faulty in this way.

Why did I have two bad sensors? The original probably just vibrated apart since they're not that well stuck in. I'm guessing when Maxima Junkie pulled the used sensor for me, he pulled on the wires to help get it out not knowing this could loosen the housing and cause a problem. There's nothing but pressure holding the rear housing in, and when the rubber gets old it probably shrinks and the rear probably just slides out.

Pushing the housing back in was easy and a lot cheaper than the $180 for a new one...

As it turns out I probably could have fixed my original, but oh well -- at least I have a working speedometer again!


-cwm9

 

thank you for posting this!!! I have the same prob with my speedometer as well, i had a feeling it was the speed sensor. Exactly where is the speed sensor located and is it hard to get to ?

 

it's DIRECTLY under the S in "Sensor". when the tranny is installed, it's kinda near the oil filter but a few inches closer to you if you are leaning over the d-side of the car. manual model has it in similar location.

 

it's a shame the search feature is a bit screwy right now, or you might have had this information before you spent money on the part. I know that the "fix" you describe has been covered here at least once within the last 5 years. though this current search misses alot of old posts

 

*snif* instead of finding something new and helpful, I find out I just reinvented the wheel.

Ok, seriously, this info should be referenced somewhere permanent if that's the case.

 

Hey my speedosensor is bad. It usually just sits at zero, but everynow and then it will jump up erratically. The problem is that I'm not sure where its at. I see the oil filter, and then I see a wire behind and below (D side) that leads up to a harness. This harness also goes to the manual transmission rpm unit (I believe). I don't think this is the speedo for the manual transmission is it? The one with teeth where you refil the tranny fluid? I went to a junkyard and tried to take out what I thought to be the speedosensor, and I had no idea how to get it off. It had a ratchet size larger than 21" and was connected to the transmission and had a cable running out of it (right near the oil filter). pictures would help alot, thanks!

 

http://forums.maxima.org/3rd-generat...need-help.html

this has pics of m/t off-car, and a/t on-car but it's in basically the same place.

anyhow the thing with the spiral gear on it where some ppl refill the m/t fluid (i refill mine in the front) is the speedsensor.

 

what do need to take the sensor off?

 

phillips screwdriver or a 10mm or 12mm socket/wrench. its held in with a single screw.

 

I got very lucky, two days ago i took the speed sensor out. Me and a co worker took it apart, ran voltage test the whole nine! It seemed as if it was done completly.So planned on going up to the junkyard and picking up a new one. So i decided to put it all back together and seal it up, once i did.I put it back on the car.And it worked, the speedo and odometer worked again i havent had a problem since!

 

So I've been driving my car around with no speedometer for like a month now. I looked at this picture: http://i164.photobucket.com/albums/u...r/IMG_0013.jpg and there are two wires coming from the black thing, one is loose, one is attached to it. I'm not so sure what I'm supposed to do, the loose wire ran to this sensor looking thing, and everything was plugged in, the other part I dont know where because I would have to get under the car.

Can anyone tell me specifically, what I should be looking for??

 

i have a very similar problem ... speedometer works one day and not the next.... or works when it wants to. i will try this fix soon.

 

i m gonna fix mine too....it sitting there spare anyways....