EPS Electronic Power Steering Please help.

duncan said:

Jaffraz32,
You can also and very easily trigger the EPS31 code if your main relay is starting to fail, and introduces intermittent, momentary 'cuts' in power.
Have you seen, say, the speedo and rev counter drop to zero and then resume their previous position.
Duncan

Click to expand...

I've not noticed any issues with the speedo and rev counter.

I recently replaced my main relay with a new one last year. I ordered allot of new parts to replace just to refresh the car basically. I could try swapping the old one back in as it was a fully working unit.


Going back to what Kaz said, how would i know if i have two sensors or not and which is the one i need to check or possibly replace? What is that part number? I have a gut feeling it's loose or not even plugged in because the gearbox was removed the same time this started but i might as well replace it while in there as it's another sensor to tick off the list that i've refreshed.

Thanks.

See the attached for the location of the Vehicle Speed Sensor [VSS1] - No 7, and the Differential Speed Sensor [VSS2] - No 8.
If you think that they are unplugged or loose surely thats the answer before replacement with new?

duncan said:

See the attached for the location of the Vehicle Speed Sensor [VSS1] - No 7, and the Differential Speed Sensor [VSS2] - No 8.
If you think that they are unplugged or loose surely thats the answer before replacement with new?

Click to expand...

Thanks...

I have found part numbers i think.

I believe they are 78410-SV4-003 and... 28820-PR9-004.

On a second thought is it possible do check the sensor from the small space down to the box within the engine bay?

Or perhaps by jacking up the car?

Or does it really need to be done on a ramp for accessibility?

I'm thinking i can perhaps check the sensor at the weekend, then order parts accordingly.

*Update*

Found this on Kaz Blog Top sensor i believe is VSS1 and the bottom VSS2

And i also found this

I can get my hand down there easy from the engine bay, will check if bolts are tight and connectors are firm.

Thanks!!

Yes, those are the sensors used by EPS.




To be precise, the lower sensor is DF sensor and it is the trigger for generating the VSS2 signal inside the Pulse unit with open collector Tr.
It is located behind the left seat and almost attached to the TCS controller.




VSS1 connector is obviously on the sensor body itself for later spec so easy to check whether it's locked or not.
Make sure the blue marked connector of DF sensor is fully locked especially if the Gbox was removed for other services.

As mentioned in my previous post, already several owners experienced EPS #33 due to this connector being loose and only half locked.


If your speedo is not showing strange behaviour as in my previous post, VSS1 is very likely to be fine.
If you are very keen, you can double check the output by turning the IG ON and spin the Rear wheel by hand and monitoring the 0 - 5 - 0V output.
VSS1 is mechanically driven by the thin ring gear pressed onto the DF case.
You can access VSS1 signal at the ECU, EPS controller, etc and much easier than trying to access the terminals on the VSS1 sensor body itself.

For VSS2, probably it’s easier if you check the signal through the Pulse unit.
You need to remove the interior trim/panel to get to the small box.
It’s looking at the final driven gear on the DF.
Same process (IG ON, spin rear wheel) and signal condition (0 - 5 - 0V) as VSS1 except the frequency.

I know at least one owner had DF sensor failure (no aftermarket parts, so natural failure) but by all means, before replacing the sensors, best to check the connection and the signal first.

Kaz

Just want to say a massive thanks to Kaz and everyone else.

So at the weekend, i reached down to the sensor gave a gentle wiggle and they were tight by hand.

then checked the clip in the blue arrow above from Kaz, looked attached but gave it a squeeze and..... *click* wasn't clicked in. Drove it, still had a light on the dash so pulled the clock fuse, waited. Put it back in and i had power steering and has seemed to have held up.

Was never so happy to here a little *Click* sound

thanks...!!

Glad everything worked out and more importantly, thanks for posting your "fix". This will certainly help others down the road.

Yesterday I got an EPS light on my '00 while driving. I feel like the power steering was still working. Once parked at work, I pulled the codes and saw an EPS code 33 and ABS code 61. According to the service manual, these indicate "A problem with average for VSS1 and VSS2" (EPS code 33) and "FSR +B voltage" (ABS code 61).

I read up on Prime, thus prepared to check a few things at home. The negative battery-cable clamp has been loose in the past, but felt tight thanks to a lead shim, but I ordered a new negative cable anyway. I didn't remove the battery to check the chassis ground point but things seemed okay. I checked the connector to the DF sensor that Kaz helpfully identified above, but it was solid. I pulled the clock fuse but when driving out to dinner later, the light appeared immediately and now I had no power steering. The difference is not subtle. After dinner, I put the Battery Tender on the car.

This morning, I removed the battery tender and again pulled the clock fuse. Now there is no EPS light. I drove to work without incident. Once there, I pulled the codes out of interest and I still get ABS code 61. But now that I look in the service manual, it looks like pulling the clock fuse will not reset the ABS DTC, and instead I need to depress the brake pedal while turning the ignition on with the SCS shorted.

It seems like, based on the above, that my battery is going bad? I appreciate any thoughts you might have.

-Jason

How old is your battery and do you always keep it on a tender? Is your alternator still charging fully?

I do not know how old it is because I bought the car five months ago and don't have records going back. I know that it was not installed by the prior owner, who bought the car at the end of 2010.

I don't use a battery tender because I drive the car daily. For my last NSX, I never once needed one. The only time I connected a tender was last night.

The voltage gauge indicates 14 volts but I have no other evidence of alternator performance.

The gauges in our beloved cars are not much better than idiot lights as their range and sensitivity are wildly variable. If your car starts every day, I think that all should be decent as to battery and alternator health.

What year is the car? If you go back and visit my threads regarding EPS, when mine stated to go, it would work one day and not the next. The clock fuse reset helped a little but the control module on the steering rack needed to be repaired. You can drive the car with no more damage being done to the EPS when it does crap out. But it does make for a little more effort required for parking lots.

My car is a 2000. I will have to see how things go. Maybe I will hold off on replacing the battery and will try the tender if it continues to have an EPS problem. If the tender seems to be eliminating the problem, then I will get a new battery. Thanks for the thoughts.

I do know the NSX is somewhat temperamental with low voltage. But if your car fires up every day.....

if it does come down to having the control module rebuilt, at least there is someone who can do it. Keep us posted and good luck.

The EPS error code #33 is the only mode that allows the power steering to stay operational even after the first time the EPS light was triggered on the dash until you switch off the IG SW.
After this, unless you reset the error code, the EPS light stays On next time when you start the engine and there will be no more power assist even under the error code #33 mode.

So, as you experienced, your power steering was still operational when you first saw the EPS warning light while driving.
You reset the EPS by pulling the Clock fuse out and then you got another EPS light afterwards.
However, on this occasion, you mentioned that you lost the power steering (at the same time you saw the EPS light???). This means that the error code you got that time was different from #33.

Personally, every time when you got any warning lights, I strongly recommend reading the error code first before resetting it even if it could be the same one as before.
Many people recommends other owners to just reset it without even mentioning the importance of reading the error code.
You are loosing one of the most important information on diagnosis.

As a side note, for the latest one body ABS like on your NSX or anyone upgraded their classic ABS (screaming ABS pump noise, leaky solenoids, etc, etc....) to the latest system, you can't reset it by disconnecting the battery or pulling the fuse.
You must follow the specific procedures that involve the IG SW, SCS terminal and brake pedal (switch).


The voltage of 14V that you saw is mainly sourced from the ACG and not the battery.

In order to test the battery properly, you need to carry out the load test. You can have your battery tested fairly easily at any car parts shop or garages. They normally have battery load/down tester.
However, as you are driving every day and you seemed to be able to start the engine without any issues, it's very unlikely to be battery related but you can do your own load test as well.

When you put the IG SW in P2 (ON position, lots of lights on the dash), you should see about 12V on the gauge.
Then, you need to be focused a bit for the next step as you only have very short window of like 0.5sec.
When you start cranking the engine, please keep eye on the gauge.
If it's about 10V or above, then your battery and battery connection would be fine.
If it's below 10V, you may have weak battery, poor terminal condition, poor cable connection, etc as the gauge on later spec NSX tends to show higher figure than the actual voltage.


The latest one body ABS uses IG2 (P2, ON position as described above) for its power supply so while you are cranking (P3, START position) to start the engine, it will loose the power connection.
When the engine starts and you release the IG key, the ABS will power itself up again.
This is the exact timing when you are very likely to trigger ABS #61 error code if you have weak battery.


By the way, have you seen any erratic movements on the speedo needle such as fluctuating reading or suddenly dropping to 0?
You will get warning lights on other controllers as well depending on how bad the VSS signal is but this will trigger EPS #33.


I would first erase ABS error code and then carry out test driving sessions until you get EPS warning light and then read the error code to confirm whether you have triggered codes other than the #33.
I already know several owners triggered EPS #22 even on the later spec EPS controllers like on your NSX due to lack of relay capacity inside the controller.
As your controller is the later version, hope it's not the controller but several failure examples here; http://www.nsxcb.co.uk/blog.php?1811&blogcategoryid=47

Kaz

Kaz-kzukNA1 said:

You reset the EPS by pulling the Clock fuse out and then you got another EPS light afterwards. However, on this occasion, you mentioned that you lost the power steering (at the same time you saw the EPS light???). This means that the error code you got that time was different from #33 .

Click to expand...

I reset the EPS and the next time I drove the car, the light was on the whole time and I did not have power steering. But when I read the code, I still only got #33 . That confused me because I expected the power steering would still work. Does it depend on whether the code is triggered during or after an initial check?

Kaz-kzukNA1 said:

In order to test the battery properly, you need to carry out the load test.

Click to expand...

The car has been fine since I put it on the battery tender each night. Interestingly, the first night it was not fully charged in the morning (tender indicated 80+% charged) but the second night it was fully charged. I will pay attention to the volt meter as you suggest and if the problem does not come back while using the tender for a while, I will discontinue using it to see if the problem comes back then. If so, I will have the battery evaluated or replaced.

Kaz-kzukNA1 said:

[To reset the ABS code] You must follow the specific procedures that involve the IG SW, SCS terminal and brake pedal (switch).

Click to expand...

I will do that. I forgot yesterday after learning the correct procedure.

Kaz-kzukNA1 said:

By the way, have you seen any erratic movements on the speedo needle such as fluctuating reading or suddenly dropping to 0?

Click to expand...

No, the speedometer has been steady and without flaw.

Kaz-kzukNA1 said:

I would first erase ABS error code and then carry out test driving sessions until you get EPS warning light and then read the error code to confirm whether you have triggered codes other than the #33 .

Click to expand...

Thanks again, will do. I will be in the UK for the next few days (driving coach!), so it may be a week or two until I report back.

-Jason

My EPS light came on, so I pulled the clock fuse and immediately went away, still ordered an ignition switch and one my connectors was corroded so I cleaned the posts up and replaced. Had a similar issue back in early September; but my ABS light and EPS light came on, we reset the codes; but could never get it to replicate itself, until it finally did; but it was only the EPS light that came on. Likely culprit back then was the ignition switch, a common issue with the year's Hondas. Had no idea the ignition switch powered some of the systems like the EPS.

I am with Kaz, make sure you give the VVS2 attention. Maybe a bad connection after the trans removal/replacement.

HTH,
LarryB

does anyone have experience with code #25 ? FET stuck or open the manual says. I am trying to troubleshoot this on a 1998. Thanks so much.

There are 8 fets in the power unit, I have replacements on hand.

Briank said:

There are 8 fets in the power unit, I have replacements on hand.

Click to expand...

Thanks Brian. I just emailed you.

Thanks all for the explanations in this thread. I just got EPS codes 31 and 33 tonight, EPS stopped working after car was turned on again, and my speedo needle happened to start freaking out occasionally (even with car off, IGN on) as well and works intermittently.

Based on your discussions, it is most likely my VSS1 connector not seated properly or corroded or the sensor itself is going bad.

I have a 1990 A/T with EPS, so my VSS1 is not the same style as the manual trans. The FSM page 14-83 shows two speed sensors on the auto trans, "NC" and "NM".

It looks like the M/T and A/T share one sensor, 28820-PR9-003/28820-PR9-004. Am I correct in assuming this is the diff ring gear sensor, or VSS2 used to feed the EPS computer? (per Kaz's post #2 here http://www.nsxprime.com/forum/showt...e-31-amp-33-was-EPS-amp-TCS-strange-behaviour).

That would make the A/T VSS1 part #28810-PR9-003/28810-PR9-004, "NM" in manual, correct? So this would be the one to potentially replace that might solve both my EPS and speedo problems.

For EPS code 31, I will check the battery grounds as well but hoping once everything's fixed and reset that it doesn't come back. My battery and alternator are <1 year old but my ground strap has been problematic before due to over-tightening. My cranking voltage stays >=10V as well so I'm hoping it will be solved by a replacement sensor and clock fuse reset.

EDIT: After reading the codes, I reset them and the EPS lights haven't come back yet and EPS works again. I assume that they will reappear sooner rather than later but I have a new VSS1 on the way to replace. It's just 1 bolt and 1 connector but tucked away under the starter.

EDIT 2: I had another failure after a long spirited drive with the speedo freaking out and the TCS light came on, but no EPS light that time, so I think the issue might've been heat related with VSS1. I just replaced it with another aftermarket sensor and everything's been working properly for now.

this is from 2005, as told to prime member jett per larry bastanza.

Jett
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Re: Electrical problem; need expert opinion but will settle for a wild guess.
The following is an itemized breakdown for the speed sensor portion of the work. Prices reflect premium Acura rates. (I will edit this post and break out the cost of the entire ordeal when I figure out where I put the other invoice.) DIY'ers should be able to do the speed sensor replacement for less than half this price, or even at less than 1/4 the price if you buy the aftermarket speed sensor. I don't have the time, place, talent, patience, or toolbox to do the job myself.

Scan system for codes $ 85.00
Speed Sensor - 211.77
Labor to replace speed sensor - 140.22
Environmental supplies & waste removal - 11.25
Tax (aprox. 2.5%, everything wasn't taxed) - 11.16
_________
Total for speed sensor replacement $ 459.40


One last thank you to LarryB. It was nice to walk into the service department the last time and be able to say "Scan the OBD1, replace the main speed sensor, and check for loose wires." Direct and to the point. The service rep looked at me like maybe I gave the appearance that I actually knew what I was talking about. For a second anyway.

I would like to point out that I am not upset at the service department. Although expensive, the work they did seems first rate. I would have hoped for more knowledgable troubleshooting, but I don't think they were trying to rip me off or anything. I will use them again. I will just try and walk in more knowledgable the next time. I also point out that if you are a capable mechanic, you can save a boatload of money doing work yourself that isn't technically that difficult. You don't pay for the work insomuch as you pay for the knowledge. Troubleshootin' is hard, parts swappin' is relatively easy once you figure out which parts to swap.

I drove the car to work today, a 150-mile round trip including a side trip I took on the way home. As I cruised downtown DC, all the hotties were out on a beautiful fall Friday night and I could hear the guys on the sidewalk saying "Hey, check it out, NSX" to their friends. (I wish I could get the same attention from the chicks that the car gets from the guys.) All systems seemed to be tight, and the car was performing great. It is in top notch mechanical condition now and although not cosmetically perfect it still looks pretty nice for a '94.

Looks like you guys might be able to help me out here. So 2 nights ago, I converted my OEM steering wheel into S2000 one.
I tested out my steering wheel by turning left and right then I noticed this feeling "bump" at dead center (car is just sitting in the garage).
It almost feels like after a slight movement, the rack tries to catch up with my steering.

Currently no EPS lights, but is this EPS failure waiting to happen? Is this solution to this problem besides rebuild?

Your symptoms are on the vague side so don't really facilitate diagnosis. Since the 'bump' feeling occurred after changeout of the steering wheel I would be inclined to check your steering wheel installation to see if you created some kind of problem in the steering column. This might include reverting to the original steering wheel.

It almost feels like after a slight movement, the rack tries to catch up with my steering.

Click to expand...

The actual rack is pretty much solidly connected to the steering column. In the electric assist portion there is no real opportunity for the 'rack tries to catch up with my steering'. With the steering column unlocked and engine not running rotate the steering wheel back and forth from center listening for noises and the feel of any play. If you feel / hear something then you may have a mechanical issue someplace. Check for the source of the noise. There are bushings on the end of the rack that can wear. If you search there are threads on Prime describing the problem, diagnosis and the repair options. However, I would expect this problem to emerge gradually and not shop up instantly. I would still be inclined to check your steering wheel install or revert to original to rule out the possibility that something got screwed up during the install. By any chance did you happen to really reef on the steering wheel nut without supporting or restraining the steering wheel?

The one thing that I can say definitively is that since your problem showed up without the car moving, it is definitely not caused by failure of the VSS!

Thanks for the tip
I will go ahead and try to reinstall everything and see if it solves anything.

Old Guy said:

Your symptoms are on the vague side so don't really facilitate diagnosis. Since the 'bump' feeling occurred after changeout of the steering wheel I would be inclined to check your steering wheel installation to see if you created some kind of problem in the steering column. This might include reverting to the original steering wheel.



The actual rack is pretty much solidly connected to the steering column. In the electric assist portion there is no real opportunity for the 'rack tries to catch up with my steering'. With the steering column unlocked and engine not running rotate the steering wheel back and forth from center listening for noises and the feel of any play. If you feel / hear something then you may have a mechanical issue someplace. Check for the source of the noise. There are bushings on the end of the rack that can wear. If you search there are threads on Prime describing the problem, diagnosis and the repair options. However, I would expect this problem to emerge gradually and not shop up instantly. I would still be inclined to check your steering wheel install or revert to original to rule out the possibility that something got screwed up during the install. By any chance did you happen to really reef on the steering wheel nut without supporting or restraining the steering wheel?

The one thing that I can say definitively is that since your problem showed up without the car moving, it is definitely not caused by failure of the VSS!

Click to expand...