Power Steering - EPS

[Kaz-kzukNA1]

Hi, all.

Recently, I was helping one of the owner for the Power Steering – EPS.


The owner bought this NSX knowing that the EPS was not working at all.
So, he visited my place for the Health Check service as well as to see what was wrong with the EPS.

First, I noticed that the previous owner disconnected all of the connectors going to the EPS controller. No wonder why EPS warning light was not triggered…

Also, there were many additional aftermarket wires installed around EPS controller which was worrying….

After some testing, all connectors were connected to the EPS controller and for the first time after purchasing this NSX, the EPS system was powered up and testd.
While the car was on the lift, it was fine until you hit the full lock/end stop of the steering rack. When it was on the ground, as soon as you move the steering wheel, it triggered the EPS Warning light and no more EPS…

So, time to read the EPS error code by shorting the SCS terminal. However, there was nothing stored in the backup memory…

The fun starts from here….

Quite often, on many NSX related website, there are comments such as 'if you see the warning light, reset the Controller by removing the 7.5A Clock fuse' and see whether it will fix the issue or not without reading the error code. For some of the controller, even the Workshop Manual states in the similar manner.

So, the previous owner or someone who worked on this NSX was following above procedure whenever he/she saw the EPS warning light.
Probably, the EPS failure was triggered quite often and the previous owner wanted to find a way to reset the EPS controller without pulling out the Clock fuse so many times.

So, here comes the additional wires...


I found a relay circuit on the EPS Backup power line and it was wired in a way that the EPS controller was always reset whenever the engine was stopped. No wonder why I couldn't read the error code after the EPS warning light was triggered.

However, this relay circuit was just hiding the failure and eventually, the issue got worse and worse. At the end, it looked like the owner or the person worked on this NSX gave up and decided to disable the EPS by just diconnecting all connectors from the controller.

EPS could fail for several reasons such as power relays inside the controller, the torque sensor, low battery voltage and so on.


We discussed several options and we decided to replace the power relays any way based on the initial test.
The new (in the clear bag) and old (bottom) relays. It's the standard 1a configuration however, if you are adventurous, you can get high current capacity 1a type and may be able to fit them by enlarging the through holes. I didn't check the circuit board on whether it is a multiple layers or not so be careful if you are planning to do so.
I couldn't get the specific high current one so we agreed to use exactly the same relay from the same manufacture knowing that it will fail again in distance future.
You need to be careful removing/installing the relays as it requires lots of heat due to the wide circuit pads. You will loose so much heat during the process...

So, the new relays were installed and the EPS controller was back on the NSX.

And, now we have EPS working perfectly for the first time after purchasing this particular NSX.

Another happy owner.


Regards,
Kaz

[markc]

It never ceases to amaze me the lengths that some people will go to effect a bodge rather than properly repair a car

No doubt HUK would have told the previous owner that the "repair" was to replace the EPS controller and/or the steering rack at an exhorbitant cost but even so the bodge he chose to do is extraordinary.

Fabulous job Kaz, proper service and maintenance in action. Please don't leave this community anytime soon

Regards

Mark

[Senninha]

........Fabulous job Kaz, proper service and maintenance in action. Please don't leave this community anytime soon

Regards

Mark

I absolutely second this comment.

regards, Paul

[Midnight Blue]

[quote=kzukNA1;64046]Hi, all.

Recently, I was helping one of the owner for the Power Steering – EPS.

The new (in the clear bag) and old (bottom) relays. It's the standard 1a configuration however, if you are adventurous, you can get high current capacity 1a type and may be able to fit them by enlarging the through holes. I didn't check the circuit board on whether it is a multiple layers or not so be careful if you are planning to do so.

Hi
Snowman reaired my EPS using the higher rated relays. They were not quite a direct replacement fit but they can be fitted.

Regards,

Andy

[bobbyswanbourne]

Just to confirm I am the lucky owner. Bought it from a TVR dealer who told me the PAS would cost £1500 to fix....

[nigel]

Sure hope you bought Kaz a few pints and slipped him a fiver.
Kaz, once again your the man!!

Cheers
nigel

[mustdav]

Kaz my EPS has just failed with a code 22 and the new unit is £1500. I noticed that they had had the same problem on the Accura NSX in th US and that Honda increased the warranty on this part to 8 years but I'm now well out of that unfortunately.
So is this the relay problem and where do I get a relay cos I am wanting to sell the car??

[Papalazarou]

Kaz my EPS has just failed with a code 22 and the new unit is £1500. I noticed that they had had the same problem on the Accura NSX in th US and that Honda increased the warranty on this part to 8 years but I'm now well out of that unfortunately.
So is this the relay problem and where do I get a relay cos I am wanting to sell the car??

Two days after I bought my first NSX (a 96 car) the EPS failed. Honda quoted me £1300,00 for the control unit. We then negotiated it to £800.00 including vat.
Basically, I bought the control box from Honda and a few weeks later sent the faulty control box to BBA reman who fixed the relays. Obviously I should have done this before I forked out the £800 but I was new to the NSX and didn't know any different.

You are right about there being EPS issues in the States, but apparently they were confined mostly to 95 cars and the recall was US only according to the info I found on Prime.

Anyway, I would suggest either sending the control box to Kaz or contacting BBA Reman.

It's got to be cheaper than the HUK route.

Cheers,


James.

[Kaz-kzukNA1]

Hi, all.
Recently, another owner contacted me with EPS failure code #22.

His EPS controller was the old version of parts no. 39980-SL0-023 which was equipped with standard spec relays that would fail after lots of EPS usage by overcooking the relays.

Honda modified the relay spec from 39980-SL0-305 onwards and it replaced one of the two relays to the high current capacity spec to overcome the common failure mode of error code #22.

As it was possible to get hold of the high current capacity relays from US this time, it was agreed to drill the extra holes to the existing board.



The standard spec on the left and the high current capacity one on the right. As you can see, the switched terminals have 3 pins compared to just one on the standard spec.


Although Honda replaced just one of the relay with the new spec, it was decided to replace both of them to the high current capacity ones for this owner. This means that I had to drill extra 8 holes on the existing board.



After the preparation, new holes were drilled. Quite delicate touch was required....



After creating the new holes, the coating was removed to enable the soldering joints around the 3 pins terminals. As new holes won't be a through hole joint, it is important to create strong connection each other.



Installed the new relays and quick test was carried out to confirm no short circuit after the modifications.

The owner installed the modified EPS controller and happy with the result.

Hope he will enjoy the EPS.

Regards,
Kaz

[Sudesh]

Great work as always Kaz!

I guess cars with EPS also loose a tiny bit of leg room on the passenger side? Never measured it up to see, have you any specs Kaz?