Speedo problem

[EK4 hatchback]

Thanks nobby! I know Kaz is an expert, i am hoping he could offer some help.

Report back, so i start it up this morning and drove it for like 15 mins about 15 km without any issues. What could be the issues causing the speedo fail after the car warm up? Thanks!

Keno

[UnhuZ]

Hi,

i think having the NSX-R speedo on a non km/h circuit board doesn't work, unless some
modification is done to the circuit board.

did that also happened with your old speedo, or only when you installed the NSX-R one?

Nuno

PS - i also have NSX-R gauges, but as i'm in Portugal, my circuit board is already in km/h

[EK4 hatchback]

Hi UnhuZ,

I have the NSXR gauge installed for 3 years, drove about 6000km on the gauge. The problem only developed in the last few months.

I used the dial on the speedo circuit board to re-calibrated, i can not say it is 100% accurate but it is close. I do know that the Europe Version NSX come with 280 km/hr speedo which match the NSXR perfectly but it is very difficult to find it. Thanks!

Keno

[UnhuZ]

Hi,

in that case, the problem can be in the circuit board itself.

As with the Bose amps and Climate ECU, the condensors (capacitors) on
the cluster circuit borads also fail, and even there is one ocurrence of a fire
in the US.

Nuno

[Kaz-kzukNA1]

Hi, Keno.

The sensor driving the speedo is called VSS (Vehicle Speed Sensor) and as you found, it is mounted on the gbox.
It's driven by the thin metal plate/ring on the DF case.

The VSS signal is used by many controllers such as ECU, EPS, AT, Auto door lock (depends on the country spec), etc and also by the cruise control.
Therefore, if VSS fails, you should see CEL and/or other warning lights for the above controllers.
Unless you have triggered any of the warning lights AND the cruise control no longer works, it is very unlikely that your VSS has failed.

On early model NSX, there are lots of owners suffering from the similar issues.
The cause of issue varies from capacitor leakage to soldering crack.

From 93 onwards, there were many changes with the pin out and functionality of the circuit boards used for the combination meter so without huge amount of modifications, you won’t be able to use the circuit board that came with the 2002+ NSX-R speedo on your NSX.
As you experienced, one will be forced to just use the NSX-R speedo panel/display and keep using the existing circuit board.

If the issue happens only when the car (cabin) gets warm, then very likely to be soldering crack.
The circuit board warps with the temperature change.
Just take a very good look at the board using the Macro mode of digital camera or your mobile phone camera and look for the soldering crack.

Capacitor leakage can be found fairly easily if you have serviced the A/C CCU or Bose AMP in the past.

By now, on many NSX, the speedo and even the tacho/rpm gauge may have lost their original accuracy.
On early model NSX, quite a lot of them are showing a few 100rpm higher reading than the actual engine speed due to the decay of electronics components.


Kaz

[EK4 hatchback]

Hi Kaz,

Thanks for your advise, i will remove the cluster/clock from the NSX and inspect it careful. I will report back, you always give us great support thanks again!

Keno

[EK4 hatchback]

Sorry for the late report. I have my cluster fixed and only have chance to put in back into the NSX about 2 months ago. So far it is working perfectly, it solved the speedo stopping issue and rpm stay high on start up issue. I have replaced all the capacitors on both speedo and rpm circuit board myself. I tried to source the exact capacitors as on the original circuit board but there is about half of the capacitors that it is impossible to find. So capacitors with same capacitance and rated voltage are suitable too (rated temperature shall be at least 85C as most original capacitor rated). Thanks Kaz taking time to reply my email and advise about the capacitors. Big thanks to Kaz!