# Digital Dash Speedo Is Not Working



## AussieZBoy (Apr 20, 2005)

Hi everyone,

I've just purchased an 1986 Non Turbo 300ZX and I'm having a problem with the digital dash. The speed display is constantly at zero regardless of what speed I am at. I have seached both here on the FSM but can't find any solution.

Before I start replacing parts I wanted to get some more information on how this system works and possible fixes. 

I have run the diagonstic test on the dash and the numbers all work so it's not that. The tacho works fine but the analogue milage guage has stopped does not increase with miles driven. Also the MPG guage next to the compass does not work either. I don't know if this is related. The car is a five speed manual.

I've looked at the speed sensor near the battery and the speed cable is connected to it as are all the wiring. The speed cable runs to under the car but I haven't checked where it's connected to to see if thats the problem.

Any help or ideas would be appreciated.

AussieZBoy


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## asleepz (Feb 24, 2004)

Your speedometer cable is probably broken. It hooks to the passenger side of the tranny just about as far back as the seat. You'll see it.

It needs to be inspected and more than likely replaced.


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## Zen31ZR (Mar 24, 2004)

Could be the pulse generator has failed. That's the device located on the passenger side fender that the speedo cable is hooked to. Only on the digital dash cars. Hopefully only the speedo cable is broken, the pulse generator is expensive to replace, unless you can find one in a junkyard.


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## havok2003 (Aug 24, 2004)

We have had a few vehicles come in at our dealership with that problem, mainly 240's, but it is probably the same set up. We had to replace both the VSS and the HUD unit to get them to work. Hope this could help in some way, but that's what I have found out.


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## AussieZBoy (Apr 20, 2005)

thanks for the info people.

will go and test these tommorrow.

Any tips on how to test the speedo cable and sender. I don't have a voltmeter so the FSM method is out of the question.

Also does anyone know of good spare parts places in Los Angeles CA, south bay area is where I'm at.


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## ICP Sux0rZ! (Jan 10, 2005)

loose connector behind the display, have it soldered and it will work


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## Zen31ZR (Mar 24, 2004)

ICP Sux0rZ! said:


> loose connector behind the display, have it soldered and it will work


He already stated the display works, it just reads ZERO. Thanks for your input...


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## Zen31ZR (Mar 24, 2004)

havok2003 said:


> We have had a few vehicles come in at our dealership with that problem, mainly 240's, but it is probably the same set up. We had to replace both the VSS and the HUD unit to get them to work. Hope this could help in some way, but that's what I have found out.


 This setup is a bit different. The 240s are mostly OBD1 anyway. The Z31s are pre-OBD, so different setup.


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## AussieZBoy (Apr 20, 2005)

I've had a look around and I couldn't work out where the speed cable connects to the pulse sensor or the transmission.

Does anyone have any pics of this? Drawing or otherwise.

Is there a way to test the pulse sensor before rplacing it. Sam with the speed cable.

Thanks for all the help so far.


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## asleepz (Feb 24, 2004)

I'll take pictures for you tomorrow.


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## AussieZBoy (Apr 20, 2005)

♣AsleepZ♣ said:


> I'll take pictures for you tomorrow.


Thanks mate. Much appreciated.


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## TechnoWizzard (11 mo ago)

Yup I got that issue too with the same year car but the speedo digits kick in sometimes. I noticed when it goes off mid drive, the speed numbers dial down as if I slammed on the brakes while I'm actually at a constant speed. But I'm 17 years too late to get a response anyway


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## mascudkoray9 (11 mo ago)

AussieZBoy said:


> Hi everyone,
> 
> I've just purchased an 1986 Non Turbo 300ZX and I'm having a problem with the digital dash. The speed display is constantly at zero regardless of what speed I am at. I have seached both here on the FSM but can't find any solution.
> Speed Test
> ...


It hooks to the passenger side of the tranny just about as far back as the seat. You'll see it.


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## Joseph_David_2312 (4 mo ago)

It should be examined and, most likely, replaced.






الدراسة في تركيا تنفيذ الديكورات و المفروشات في السعودية​


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