It's about speed sensors.
My car has a speed sensor that sometimes doesn't and sets of p0500 code every long trip I take. Today I was lucky enough to be able to catch it in a working time and go on a trip to systems readiness drive it to get it smogged and driving at 57.2 mph steady for about 20 minutes did the trick first it was the catalyst that completed then the oxygen sensor which is what I was looking to get done.

It is a 1996 Infiniti J30

3 questions

1. How do I find the speed sensor I've never even been able to see a transmission down there since it is all covered by catalytic converters can you guys please tell me how to take the speed sensor out.

2. If my speedometer always works then do you think it is the speed sensor that is bad or the speedometer not creating the voltage banging on the dash doesnt help. The speed sensor might work now and if I turn off the car and restart it it might not work at all its so wierd. But I sure appreciate it when it works. I got 24 mpg cruising at 40mph after changing all my injectors.

3. is the 300zx speed sensor interchangeable with 1996 infiniti j30 and if it is can you please tell me what year?

Also a random bonus question
I got code p01443 I disconnect the hose coming of of the evap solenoid circuit hose from the throttle body and it goes away. Can you guys tell me the schematics for which hoses goes to the intake and where vise versa.
Thank you

Respectfully,
Los angeles Mr2

I get p500 on mine all the time. I got a VSS from the junk yard (figured out where it was from that before taking it out of my car). It wasn't super hard to do, it was the wiring that was a pain and laying on your back under the jacked up car and removing the wire from the other wires it's zipped to and then routing it over the transmission. However, changing the VSS didn't solve my issue. I suspect the issue is elsewhere for me.

A mechanic I talked to said if the VSS weren't working the speedo would probably malfunction so if your speedo is malfunctioning then changing the VSS could be the fix for you. It's expensive though (179.99 is the cheapest one from rockauto).

mine looked like the silver one in this pic
http://i126.photobucket.com/albums/p112 ... G_6808.jpg

it's 25010Y circled in this pic
http://i211.photobucket.com/albums/bb31 ... nS13MT.jpg

http://i116.photobucket.com/albums/o13/ ... G_1719.jpg

It wasn't hard to remove. I think I paid 5 bucks for the one I got from the you pull it yard but it didn't fix my problem. It mounts on the passenger side as you can see in the 3rd pic has 1 bolt to hold it in then the cable goes over the transmission to the driver side and plugs in.

I keep a obd2 scanner on my driver side floorboard and plug it in and reset whenever it pops up but I would like to solve my issue...it just seems to be either at the computer or maybe at the cluster where the information from the vss is triggering the code somehow.

Bonus: Can't really help you there but do you have the FSM?

http://www.nicoclub.com/archives/infini ... nuals.html

Youre the man thank you But If my speedometer works perfectly but the obd2 sensor only sometimes indicates a speed to the ecu as in I can get a speed reading from a computer attached to the obd port then Im guessing it is the speedometer or the ecu. I cant afford to change all three but I dont get it should I try the speedometer and then the other i dno

you might want to try to adjust your TPS (throttle positioning sensor).
I had the same issue...and it was the positioning of the TPS....do you have a gear-shifting hesitation from the transmission?

Only from first to second and yes I do. Does that really matter with the speed sensor getting a signal to the ecu? I don't get how that could make sense.

And every time I restart my car most codes are deleted for the most part they just reappear every time I go for a long drive up to 20 to 40 miles

Is there a reason why codes are deleted so easily on my car. Or is it maybe that it has a partial reading and it just doesnt display it back out to me. Because the speedometer works just fine. I wish I knew what to change smog check it coming up and I don't have that many tries left.

the speed sensor works only sometimes as in when my odb scanner is connected to the obd port and I get a reading.

ok...I gave you the answer that fixed my problem....

Okay guys I fixed my problem.

I tapped on the dash and the obd scanner would read a speed even though the car wasnt moving and So i knew this was the speedometer that needed to be fixed.
I fixed it by taking it out and resoldering every single solder point that had brown around it kinda like flaky brown stuff like old powdery seat cushion and I unbolted all the bolts and took a scotch bright and went over all the connections and even the connections where the pins go into I plug it up and it all worked.

I first took apart the speed sensor after I raised the car it was so clean down there I was so impress. The car has 158k miles I bought it with 2500 it has been nothing but problems But i fixed every single problem

I have fixed the radiator
water pump
timing belt
injectors
valve seals

upper and lower plenum gaskets

all hoses
and the really thick hoses too that go from the plenum to the iacv theyre really flexible I love them makes them so easy to install and even then it is hard.

My car gets better mpg than a new infiniti j30 because its already broken into Trust me its mechanics have way outlasted the interior/

The sunroof doesnt work the seats are all cracked windshield cracked but it is so reliable.

The transmission shifts hard from first to second almost always I think its because I used to race it. Lol I heated the disc calipers so bad once it wasnt even holding it was just rolling foward down a mountain I got so lucky there was open space in front of me.

Resoldering all the joins on the cluster fixed the problem, but You also have to unscrew the speedometer unit from the custer and resolder that too. I am also LosangelesMr2 This was my original question hehe

Good to know you got it all sorted out. I probably need to remove my cluster and do the same...but my speedo still works. I just get the CEL code randomly.