# Speed Sensor Problem



## sjaltobelli (Nov 7, 2012)

This is a first time post and I appreciate any assistance.....

1995 Nissan D21 Pickup

A few months ago, my speedometer stopped working. I pulled the speed sensor and it was seized and the plastic gear was destroyed. I ordered a new sensor and gear and installed. The speedometer worked for a few weeks, but then would only work intermittently, maybe 10% of the time. Now it does not work at all. 

I did a continuity check from the sensor all the way to the harness under the steering wheel to the left of the clutch and everything check out good. The resistance through the speed sensor is 270 ohms, which I believe is a good reading based on some online research. I have not taken the dash apart to check the combo meter. I disconnected the sensor and did a volt check across the two leads while the car was in driving and I did not get any voltage from the sensor. I had the volt meter on AC and I believe I should be getting a reading of a few volts as the car drives.

Is it possible that the sensor is not spinning? Is there a C clip or something that holds the gear in place on the shaft of the sensor? I did not use anything to hold the gear on as I thought there was a stop inside the transmission that would stop it from walking once it was installed. 

I would also like to mention that I did have the center support bearing replaced right before the sensor malfunctioned the first time. Could the driveshaft have been installed improperly causing an issue with the sensor?

Thanks for any help.

Steve


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## SPEEDO (Jun 9, 2003)

I would pull the sensor and check it, but I would lean towards a bad speedo


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## smj999smj (Jan 1, 2006)

There is a circlip on the end of the pinion shaft that keeps the plastic gear on. As far as testing the speed sensor directly, you will usually get approx. 1 volt per every 10 mph. This is not a perfect test, but it will let you know if the sensor is generating a voltage signal. Without any voltage signal from the speed sensor while driving, I would hold off on replacing the speedo head until that issue is resolved.


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## sjaltobelli (Nov 7, 2012)

So it sounds like it is not working because I did not install the clip. Hopefully the gear is not stuck in there.


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## sjaltobelli (Nov 7, 2012)

Can I get the clip from a local hardware store? It should have come with my order since I ordered the assembly, but thats a different story.


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## SPEEDO (Jun 9, 2003)

the speed sensor comes w/o the gear, did you put the circlip from the old one on the new one? (how did you attach the new gear to the new sensor?) the gear may have come off (might be chewed up by now) let us know...


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## sjaltobelli (Nov 7, 2012)

When I pulled the old sensor a few months ago, the gear was destroyed and I do not remember a circlip.

I bought a sensor and a gear from the dealer. When I installed the new sensor and gear, I did not put a circlip on. I assumed that there was a stop in the transmission that would prevent the gear from coming off.


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## sjaltobelli (Nov 7, 2012)

I will be pulling the sensor this Saturday. Hopefully the gear is not stuck in there somewhere....


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## smj999smj (Jan 1, 2006)

The part you need is called a "ring lock, speedometer pinion." It's MSRP from Nissan is less than a dollar and part number: 32744-35F00. You probably could find something in a hardware store or just get it from you local Nissan dealer.

Part Detail


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## SPEEDO (Jun 9, 2003)

sjaltobelli said:


> I will be pulling the sensor this Saturday. Hopefully the gear is not stuck in there somewhere....


good luck, let us know what you find...


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## sjaltobelli (Nov 7, 2012)

When I pulled the sensor, the gear came out as some of the gear oil dripped out. With the sensor removed, I started the truck and turned the sensor by hand and the speedometer bounced up and down, a good sign. I ordered the clip from the dealer. 

I want to top off the oil in the transfer case (since some of the oil dripped out). The book recommends Dexron ATF. Is that the case even in a manual transmission? I have always used a 80W-90 gear oil in other vehicles. What does everyone recommend? Not recommend?

Thanks for the help!


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