Speedo problem

Hi,

My speedo is not working. Originally i thought it was the speed sensor on the transmission, the problem was once the car warm up the speedo just stop at 0km/hr. So when i start it up in the morning and drive it out it would work for about 5km then it stop working. It was like this for last couple months. So today i went to replaced the speed sensor on the transmission with a new one from Honda and the speedo is working again. But it only worked for around 100km, now it stopped working again. I noted the meter below counting the mileage still working so the speed sensor is working for sure. It seems there is something wrong with the speedo circuit board, i would like to you know if anyone have this experience and how to fix it. Thanks.


My NSX is a 92 with 180 mile/hr speedo circuit board but I current have the NSXR (+2002) speedo installed so the speedo itself is like new. Thanks

Keno

Kaz may be able to shed some light on this for you.

hopefully you get it sorted

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

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

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

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

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

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

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!

Glad you managed to fix the issue.
If you replaced the caps with different spec, you may want to double check the speedo against the GPS as you may have introduced some error between the two.
Car manufactures tend to on purposely set the speedo reading bit higher than the actual figure but it could go the other way round after replacing the caps.
You should be able to adjust it by turning the small VR at the top of the gauge. You can access them behind the sticky tape.


The capacitor leakage and damages to the circuit board on the gauge assy are becoming common failure these days as our NSX is getting really old.



https://lh3.googleusercontent.com/-t...00/Dash_01.jpg
Currently, Mr Toyoizumi at T3Tec are dealing with 6 dash gauges in a row.


The common failure mode is the speedo showing much lower figure compared to the actual GPS reading and the famous ‘BRAKE LAMP’ warning indicator stays On forever even when there is no bulb failures at the brake lights.



https://lh3.googleusercontent.com/-f...40/Dash_02.jpg https://lh3.googleusercontent.com/-f...40/Dash_03.jpg
This NA1 Type-R speedo should be at 180kph at this signal frequency but only showing just over 100kph.
Another gauge showing the correct speed at the same frequency but the ‘BRAKE LAMP’ warning stays On even when the detection circuit is connected to the GND.


The ‘BRAKE LAMP’ warning can be triggered by several reasons but if you checked all of the light bulbs and the big 20pin connector at the left forward section of the boot behind the carpet and still getting the same issue but intermittently, then you may want to consider servicing the dash gauge assy.

It could be the first sign of the serious 'burnt dash gauge' issue......



https://lh3.googleusercontent.com/-A...00/Dash_04.jpg
I originally saw the burnt dash gauge example on NSX Prime but it also happened on several NSX in Japan.

On one occasion, it ended up with serious discussion between the Honda customer support, R&D, gauge manufacture, fire department in Japan as it was considered to be production car fire incident on the public road.
You don’t want to see smoke suddenly coming out from somewhere behind the steering wheel while you are driving…..


Kaz


[All photos are courtesy of Mr Toyoizumi at T3Tec, Japan. Thank you for allowing me using these photos.]

This is my next winter project. I thought I've done them all (A/C, BOSE, SRS, ECU, TCS) so this is my next and hopefully last one.

Hi Kaz,

Thanks for tip on checking the speedo accuracy. I will do that next time when I get on the freeway.

My brakelight on the cluster was lighting up occasionally before so I will see if it happen as you mention that is a serious fire problem which shall be a big caution for everyone. Thanks for sharing!

Impressive test rig.
Is this a service you will be offering Kaz?

Quote:

---

Originally Posted by Kaz-kzukNA1

Glad you managed to fix the issue.
If you replaced the caps with different spec, you may want to double check the speedo against the GPS as you may have introduced some error between the two.
Car manufactures tend to on purposely set the speedo reading bit higher than the actual figure but it could go the other way round after replacing the caps.
You should be able to adjust it by turning the small VR at the top of the gauge. You can access them behind the sticky tape.


The capacitor leakage and damages to the circuit board on the gauge assy are becoming common failure these days as our NSX is getting really old.



https://lh3.googleusercontent.com/-t...00/Dash_01.jpg
Currently, Mr Toyoizumi at T3Tec are dealing with 6 dash gauges in a row.


The common failure mode is the speedo showing much lower figure compared to the actual GPS reading and the famous ‘BRAKE LAMP’ warning indicator stays On forever even when there is no bulb failures at the brake lights.



https://lh3.googleusercontent.com/-f...40/Dash_02.jpg https://lh3.googleusercontent.com/-f...40/Dash_03.jpg
This NA1 Type-R speedo should be at 180kph at this signal frequency but only showing just over 100kph.
Another gauge showing the correct speed at the same frequency but the ‘BRAKE LAMP’ warning stays On even when the detection circuit is connected to the GND.


The ‘BRAKE LAMP’ warning can be triggered by several reasons but if you checked all of the light bulbs and the big 20pin connector at the left forward section of the boot behind the carpet and still getting the same issue but intermittently, then you may want to consider servicing the dash gauge assy.

It could be the first sign of the serious 'burnt dash gauge' issue......



https://lh3.googleusercontent.com/-A...00/Dash_04.jpg
I originally saw the burnt dash gauge example on NSX Prime but it also happened on several NSX in Japan.

On one occasion, it ended up with serious discussion between the Honda customer support, R&D, gauge manufacture, fire department in Japan as it was considered to be production car fire incident on the public road.
You don’t want to see smoke suddenly coming out from somewhere behind the steering wheel while you are driving…..


Kaz


[All photos are courtesy of Mr Toyoizumi at T3Tec, Japan. Thank you for allowing me using these photos.]

---

Hi Kaz,

there are two VR1 and VR2 potentiometers- trimer on a single printed circuit board.
You can explain to me what it affects VR1 and what VR2

Mario

Hi,
I have asked for an explanation to Mr. Toyoizumi from T3Tec.
I received a reply in Japanese or there is someone who could help me translate (Google translator is not precise)

Mario says:

https://mail.google.com/mail/u/0/images/cleardot.gif

おはようございます

私はGoogleの翻訳者を使っていますが、あなたが理解しているかどうかわかりません
英語で書けますか。
ヨーロッパでは、PCB speedo用のVR1およびVR2ポテンショメータが何のためにあるのか私には説明できません



敬意の言葉

Mr.Toyoizumi says:
私　英語分かりません。

SpeedMeterの基板？
VR1　VR2は
速度の補正
不具合が起きているのでしょうか？

Mario says:
Acura NSXを持っています
スピードメーターをkph-EUに変更しました（mph-USから）
GPSを使って表示を修正したい（私はT3Tec Nsx Meter Testerを持っていない - 残念ながら）
私はVR1がどう変わるのか、VR2がどう変わるのかを尋ねたかったのです。
例：スピードメータースケールのゲイン調整、オフセット、直線性

Mr.Toyoizumi says
なるほど。

２個のボリュームは
低速レンジと
高速レンジです

オフセットとゲインの関係もあるけれど。

まず、120km/h程度でVR1を調整し
40㎞/h程度でVR2を調整していきます

できれば
高速側は
速度が高いほど誤差は少なくなります


I do not know how to express my gratitude to Mr Toyoizumi in words.
I am asking for a hint

https://ssl.gstatic.com/ui/v1/icons/...s/cleardot.gif

At first let me state that my Japanese is quite basic (my brain seems to have issues keeping more than two languages at a time - or I'm simply too old ..)

After correcting some of the line feeds (to make the job of Google Translator a bit easier) it came up with a reasonable result, which i tweaked further:

I use a Google translator, but I do not know if you understand
Can you write in English?
In Europe, I can not explain to me what the VR1 and VR2 potentiometers for PCB speedo are for.

A word of respect

I do not understand English.

The Speedo PCB?
Did VR1 and VR2 speed correction problems arise?

I have an Acura NSX
Changed the speedometer to kph-EU (from mph-US)
I want to fix the display using GPS (I don't have T3Tec Nsx Meter Tester-unfortunately)
I wanted to ask how VR1 changes and how VR2 changes.
Example: Speedometer scale gain adjustment, offset, linearity

I see.

There are two potentiometer, one for the slow and one for fast speed range.

There is an additional relation between offset and gain.

At first, adjust VR1 at about 120 km/h and VR2 at about 40 km/h.

If it's possible use a higher speed. The higher the speed, the lower the error. (probably relates to VR1)

He probably suggested 120 km/h as the Japanese highway speed limit is 120 (my guess, to not encourage speeding) but a higher speed would be better for accuracy.
From the T3TEC screenshots that Kaz posted a while ago they do test with 180 km/h, it seems.

Regarding a thank you, this page might be of interest: https://www.livinglanguage.com/blog/...ions-you-need/
From my (foreign) experience, it's the thought that counts and not so much a perfect handling. If in doubt, rather use something simple than nothing at all :)

PS: Now I'm ready to be smashed to pieces for my limited Japanese but at least I tried :rolleyes:

I have also just put this through my translator and this is what it came out with:



Good morning


I use a Google translator, but I do not know if you understand
Can you write in English?
In Europe, I can not explain to me what the VR1 and VR2 potentiometers for PCB speedo are for






A word of respect


Mr. Toyoizumi says:
I do not understand English.


SpeedMeter substrate?
VR1 VR2
Speed ​​correction
Is the problem happening?


Mario says:
I have an Acura NSX
Changed the speedometer to kph-EU (from mph-US)
I want to fix the display using GPS (I don't have T3Tec Nsx Meter Tester-unfortunately)
I wanted to ask how VR1 changes and how VR2 changes.
Example: Speedometer scale gain adjustment, offset, linearity


Mr.Toyoizumi says
I see.


2 volumes are
With low speed range
It is a high speed range


There is also a relationship between offset and gain.


First, adjust VR1 at about 120 km / h
We will adjust VR2 at around 40km / h


if you can
The high speed side is
The higher the speed the less the error

Colleagues,
I would like to thank you for your help in translating. I carried out the speedometer correction - I do not recommend running on the highway - it's dangerous. The future is better done with the help of the waveform generator. Since I have Aftermarket wheels (different wheel diameter) I wanted to reduce the error.
Thank you again for your help