# Speedometer issue 300zx 91' tt



## nix0r (Jun 7, 2006)

Well about a month ago my speedometer went out, when taking it on the highway and getting around 60mph the speedo kicked back in and was working fine till i turned it off, so i had to repeat the speed to kick it on again. Well i searched online and read something about having a sensor over front tire (probaly missread it and was mentioning the 300zx z31) and tried to clear the gunk out of the "what i thought to be sensor" with wd40, well after that it totally wasn't working. Was also getting problems with my hicas light coming up after driving for awhile and hard steering, which if I can find the reference for that, it said those were tied into the sensor going bad. I have so far replaced the sensor, which my speedo kicked on after awhile but went back out again. Haven't messed with the wire yet, and need to know if the wire goes from the tranny all the way up to the dash or if there is a break to check it at, or wondering if there is more than one sensor. My odometer and tripmeter don't work either, since this has happened. Thank you for any help.


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## Spongerider (Nov 18, 2002)

nix0r said:


> Well about a month ago my speedometer went out, when taking it on the highway and getting around 60mph the speedo kicked back in and was working fine till i turned it off, so i had to repeat the speed to kick it on again. Well i searched online and read something about having a sensor over front tire (probaly missread it and was mentioning the 300zx z31) and tried to clear the gunk out of the "what i thought to be sensor" with wd40, well after that it totally wasn't working. Was also getting problems with my hicas light coming up after driving for awhile and hard steering, which if I can find the reference for that, it said those were tied into the sensor going bad. I have so far replaced the sensor, which my speedo kicked on after awhile but went back out again. Haven't messed with the wire yet, and need to know if the wire goes from the tranny all the way up to the dash or if there is a break to check it at, or wondering if there is more than one sensor. My odometer and tripmeter don't work either, since this has happened. Thank you for any help.


Your speed sensor is located on the tranny. Make the connectors are clean and connected. You might have to replace the sensor? As for your HICAS make sure you have enough power steering fluid in you reservoir.


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## nix0r (Jun 7, 2006)

As it looks right now the 3 problems I'm getting, speedometer not working, stiff steering and hicas light coming on all seem to be tied to the speed sensor or cable. As I can't say these 2 links are verified in saying that it is tied together just going to have to hope it works.
http://www.a2zautoforums.com/showthread.php?p=32849
http://forums.freshalloy.com/showthread.php?t=138688

Thanks for the info spongrider, since I've already replaced the sensor, I'm going to check it out for slippage. The only thing I need to know is where to test the speed sensor cable at, and how hard of a process is that to change out if needed? thanx


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## Spongerider (Nov 18, 2002)

nix0r said:


> As it looks right now the 3 problems I'm getting, speedometer not working, stiff steering and hicas light coming on all seem to be tied to the speed sensor or cable. As I can't say these 2 links are verified in saying that it is tied together just going to have to hope it works.
> A2Z Automotive Forums - 94 Nissan 300ZX TT speedometer failure plus check engine & HICAS lights
> Found a 91 300zx TT for sale. - FreshAlloy.com Forums
> 
> Thanks for the info spongrider, since I've already replaced the sensor, I'm going to check it out for slippage. The only thing I need to know is where to test the speed sensor cable at, and how hard of a process is that to change out if needed? thanx


The speed sensor and HICAS work together when you reach 40+ mph at which time the HICAS will activate. If you're steering is hard to turn and you are not reaching 40mph then you are low on power steering fuild and need to refill it. As for your speed sensor make sure you replaced it with TT speed sensor and not a NA. Also make sure your senser is replaced with Nissan OEM parts.


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## mpetty318 (Aug 25, 2009)

I am having the exact same problem with my 1991 300zx now turbo. Did you find out what the actual problem was?


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## jmiller11784 (Oct 23, 2010)

I know this thread is older, but from what I've heard this is a common issue.
I'm currently working on resolving the problem, and through research have learned the following:

the heavy steering, and hicas malfunction lights are most likely connected to the speed sensor unit (located on the transmission, held in by one 10mm bolt.)

More information here:
TwinTurbo.NET: Nissan 300ZX forum - Nothing to remove, just take the 10mm bolt out that

Online Nissan 300ZX service manual (In the steering section of the online manual, go to page 31 and it has a description of the symptoms)


I'm still working on resolving this issue, and have pulled and tested the speed sensor. I believe if it's functioning properly it will produce a charge of 0.5 volts AC. If it does and you're still experiencing issues, it could be a wiring issue, but don't quote me on that one  

If anyone has additional information about this, please shoot me a PM, as it would be helpful. Thanks!


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## Armanip (Nov 6, 2010)

Hey, I have the same issue, but the boost gauge underneath the speedometer isn't working in mines. Is this happening in yours too? should the boost gauge be effected by the speedometer sensor?


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