95 NSX strange behaviour from EPS and TCS warning lights.

Hi all,

I've searched the forum but can't find any similar behaviour to mine...

2 things.
1) TCS warning light is on. Stays on after starting, but when the SCS diagnostic is connected, it just stays on. No blinking or flashing.
2) EPS warning light comes on above 20 or so mph. Stays on for the duration of the trip, and doesn't seem to switch off the power steering, so it's still easy to park at the end of the trip. Switch the car off and then on again, and the light is off until you go over 20 or so mph again. Again, no error codes.

Also, not sure if this is in any way relevant or whether all cars do this, but. If I connect the SCS diagnostic ports together, and switch the ignition on, the ABS and EPS warning lights are off. Pull the SCS while the ignition is switched on and they both come on as they would before the engine starts. Is this normal?

I'm a little confused and would be grateful for any steer.
Cheers
Matt
1995 euro NSX-T

I know this may seem like an odd question, but is your clock working?

Regards,
LarryB

Larry Bastanza said:

I know this may seem like an odd question, but is your clock working?

Regards,
LarryB

Click to expand...

Oh, man. You're too good.

I've just been down and checked, and no, the clock wasn't working. I hadn't spotted that. Previously I checked the clock fuse visually and it seemed fine. I don't have a spare 7.5A, so I put a 10A in and all of a sudden the clock works. So, I started the car and the TCS light goes out. Bingo.

I've examined the 7.5A that came out of the car and still can't see anything wrong with it. I'll try and take a pic. It's clearly broken as the tester says there's no circuit, but there's no way to know visually!

I won't have a chance to drive the car today and see what happens to the EPS, but if I were a gambler I would bet that it stays out too. I'll report back when I can.

Thank you so much from a thundery Switzerland

Matt


For what it's worth, here's a bad pic of the blown fuse. It looks perfect!

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EPS codes 31 and 33 - was "strange behaviour from TCS and EPS warning lights"

cccscotland said:

I won't have a chance to drive the car today and see what happens to the EPS, but if I were a gambler I would bet that it stays out too. I'll report back when I can.

Click to expand...

If I were a gambler I would have lost my money. EPS light comes back on, and after it comes on, the next time the car is started there is no power assistance. However, the TCS problem is now fixed! Hurray!

Curiously, when the light comes on for the first time after clock fuse reset, the power assistance remains until the car is stopped. Also, it now lets me pull codes: 31 & 33.

31 I understand to be related to the ignition switch and 33 the speed sensor/s. However, there are no other signs of trouble - would the speed sensor fault also show up as a dodgy speedo? Should I change the speed sensor, and is there any way of knowing which? Or is it more likely the EPS board itself is faulty?

One last random thing. When I turn on the ignition there is a very loud double click from a relay in the passenger footwell. Could that be telling me something is wrong?

Thanks again in advance for any help you can offer.
Cheers
Matt
95 NSX-T (euro) with 6-speed transplant.

OK, I did anticipate your VSS (Vehicle speed sensor) could be the issue, but the warning light behavior was strange. FYI, the 7.5 amp clock fuse runs the ECU memory, which is why the lights were strange, which is why I asked.

HTH,
LarryB

Larry Bastanza said:

BTW, is the car right or left hand drive?

HTH,
LarryB

Click to expand...

Prolly LHD as only seven European jurisdictions drive on the left: the United Kingdom, Ireland, Isle of Man, Guernsey, Jersey, Malta and Cyprus. And thankfully none of them shares a border with a country that drives on the right. Can you picture that border crossing?

Larry Bastanza said:

BTW, is the car right or left hand drive?

Click to expand...

RHD. Does this speed sensor not drive the speedo? If so that would explain why the speedo works fine.

Will get one and report back.
Cheers for the help!
Matt

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Hugh said:

Prolly LHD as only seven European jurisdictions drive on the left: the United Kingdom, Ireland, Isle of Man, Guernsey, Jersey, Malta and Cyprus. And thankfully none of them shares a border with a country that drives on the right. Can you picture that border crossing?

Click to expand...

Actually in pre-war Italy (where else?) they had a rule whereby one drove on the left in towns and on the right in the countryside. God only knows how that ever worked out!

Actually my data above might be incorrect about the speed sensor. IT is not clear to me if your 1995/non-US has the single or dual speed sensors. In the US in 1997 they updated the EPS system and two separate speed sensors are used. The VSS WOULD have an effect on the speedo, so it IS NOT the part number I described above. It would be the other one.... but I cannot really speculate since the car is not a US car and I have no info. If you have a service manual and you can see the speed sensor(s) it may become clear.

In regard to my question about RHD, I Was thinking the clicking may be the ABS system, but I am thinking that may be something else, not sure on that one....

Regards,
LarryB

Larry Bastanza said:

Actually my data above might be incorrect about the speed sensor. IT is not clear to me if your 1995/non-US has the single or dual speed sensors. In the US in 1997 they updated the EPS system and two separate speed sensors are used. The VSS WOULD have an effect on the speedo, so it IS NOT the part number I described above. It would be the other one.... but I cannot really speculate since the car is not a US car and I have no info. If you have a service manual and you can see the speed sensor(s) it may become clear.

Click to expand...

I have no idea whether it has one or two. I do know that when I fitted the six speed box (an E6E?) every wire seemed to find a home without a problem. I'll have a look next week sometime and see what I can see! I read of an NC and an NM sensor - is the NM one that drives the speedo and the NC for all the electronics?

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Larry Bastanza said:

In regard to my question about RHD, I Was thinking the clicking may be the ABS system, but I am thinking that may be something else, not sure on that one....

Click to expand...

It doesn't sound like an abs system, more a relay in the car footwell rather than on the other side of the bulkhead. And it is just 2 loud clicks as the key is turned.
Cheers
Matt