Weird Speedo problem on my 91

[NSX-GT]

Hi all,

Got a weird problem with my NSX lately. My OEM speedo wouldn't work, for i dunno, the first 5-10min of a cold start, all the other needles work, temp/fuel/tach. Just the speedo needle would be stuck at the 0 for the longest time. Then all of a sudden it starts working again after driving for a bit. I just hope it's nothing serious? Don't really want to have buy a new cluster lol. Anyone have issues such as mine before?

 

[steve k]

Hi NSX-GT,
probably not your speedo but the speed sensor. The factory sensor is a tad pricey but if you google the sensor on e bay you can get the made in china ones for anywhere from $5 to $12 dollars,the one i installed was for a civic i belive but was compatable,even the pigtails worked.
you should be able to search on prime for the install.

 

[A.S. Motorsport]

That's VSS sensor, fairly easy fix, yet it's specific to the NSX has it meshes with your differential ring gear.
The usually die every 15-20 years.

On a NSX it's a cast aluminum assembly which you can dissemble and remove the sensor, there are two types one with a direct connector other has a wired connector.
The latter is 1990-1993 and the later with the direct connector looks more similar to normal Honda's

The part number is NSX specific (xxxxx-SL0-xxx) so there might a output difference to work with NSX's EPS or TCS systems.

 

[Larry Bastanza]

VSS part is available in the US. P/N 78420-SL0-505 SENSOR ASSY., SPEED

Or as mentioned above you can get it aftermarket.

HTH,
LarryB

 

[Kaz-kzukNA1]

Addition to the speedo staying at zero, do you get any warning lights?

As your speedo stays at zero from the point you started the engine and even after start driving plus the speedo doesn't jump around or suddenly drop out to zero while driving, it’s very unlikely but it could trigger CEL #17 with VSS failure.
There are several modes with VSS failure that won’t trigger any warning lights and your case is very likely to be one of them.
It will affect the VTEC and rev limit but I’ll leave them for now.

If you own AT model, it will trigger EPS warning light and flashing ‘D’ indicator if VSS stays at zero while driving.
If you own MT model, then you won’t have EPS on 91 model unless you retro-fit it so no EPS light....

Does your Cruise Control (CC) operate properly while your speedo stays at zero?
With faulty VSS, the CC won’t work at all, can’t hold the targeted speed or big difference between target and actual speed.

I believe when the speedo stays at zero, both the odo/trip meters also don’t count up so I’ll leave them.

As it seems to be fairly consistent and easy to re-produce the same issue on the car with cold start, you could place the car on the lift or raise the rear wheel and spin the rear wheel while monitoring the signal output of VSS directly at the sensor connector.
It’s 0 - 5V square wave so you can use multimeter to see the voltage change.

There is a chance that your speedo driving circuit is damaged by the leaked acid from the capacitor as well but hope you can fix your speedo issue by just replacing the VSS.

Kaz

 

[dquarasr2]

I have the exact same problem with my '91.

I replaced the speed sensor at the transmission - DID NOT FIX IT. I suspect I have a problem with my instrument cluster, the infamous leaking capacitor problem.

A number of years ago I was driving along and smelled a burnt plastic odor. I dismissed it as being from outside the car as I had the windows open. I can't recall exactly whether the speedo problems started before or after that, but it was somewhere around the same time.

Don't take this lightly. Ask IRVINFLA. His dash caught on fire. Luckily he has it repaired in time for NSXPO but he was pretty upset and had to source a used dash.

Where are you located? I have a "spare" sensor I can send you. You can see if it fixes your problem, then send it back, rather than spend the $150 or so on a new one just to see if that's the problem. If NOT, then you'll need to address the cluster.

 

[NSX-GT]

Thanks for the replies guys. I just recently bought a S2000 cluster and the plug-n-play solution Johan was offering on the vendor forum. I'll be swapping my old cluster out for that, then i'll take apart my cluster to see if the pcb is ruined... If my S2000 cluster doesn't work, I assume it'd be the VSS problem you guys mentioned (I'm guessing that's apart from the cluster)

And Kaz, thank you for your info especially, I googled the leaking cap. problem just now and came accross your posts. Very imformative. But no, no other warning lights seem to come on on my 1991 MT RHD NSX, once the speedo starts working/moving, everytrhing seems fine. Did not test cruise control. Just thought it was a strange problem.

dquarasr2: Thank you for the generous offer as well, but I'll see how it goes first with the s2000 cluster as I'm located all the way in Hong Kong.