EPS error

[emdoller]

My ‘95 NSX with 18k miles. Several months ago my EPS light came on. I didn’t read the code because my battery had died and I thought this was the cause. I reset the EPS light by pulling the click fuse.

I haven’t driven the car much since then and because I have a smog check I decided to plug into OBDII and make sure it was ready. It wasn’t showing “Catalyst” test not completed. While driving it around to see if I could get the catalyst reset, the EPS light came on. This time I read the code and it was 22. I checked my battery cables and things seemed tight. I decided to reset the EPS by pulling the fuse. After doing this it reset but lit up after a minute or two after starting the car.

Given what I’ve read it’s likely the EPS module needs to be fixed. I’ve emailed BrianK and hope to get his opinion.

Anything else I should try?

As always, thanks. No way I could have gotten this far without this forum.

Ed

 

[triple18s]

My ‘95 NSX with 18k miles. Several months ago my EPS light came on. I didn’t read the code because my battery had died and I thought this was the cause. I reset the EPS light by pulling the click fuse.

I haven’t driven the car much since then and because I have a smog check I decided to plug into OBDII and make sure it was ready. It wasn’t showing “Catalyst” test not completed. While driving it around to see if I could get the catalyst reset, the EPS light came on. This time I read the code and it was 22. I checked my battery cables and things seemed tight. I decided to reset the EPS by pulling the fuse. After doing this it reset but lit up after a minute or two after starting the car.

Given what I’ve read it’s likely the EPS module needs to be fixed. I’ve emailed BrianK and hope to get his opinion.

Anything else I should try?

As always, thanks. No way I could have gotten this far without this forum.

Ed

Check the power cables that connect on the bottom side of the steering rack.

You can try measuring the voltage and continuity on the top two connectors that plugs into the eps module.

Inspect tie rod boots for tears.
Code 22 can be a short in the rack.

In my case the EPS module was okay when it was sent out for repair.

 

[emdoller]

Thanks! I’ll check it out.

 

[triple18s]

This is how mine looked. Wires are behind a cover

 

[emdoller]

Thanks for the pics. I will check but if I had to guess, my money is on the module mostly because my car is low mileage and never driven in the rain. REALLY appreciate the pictures… that will make it easy. Love this forum.

 

[emdoller]

Removed the EPS unit this morning. Not to bad of a job but always concerned with 30 year old clips. Sent it out to Brian K.

 

[Valhalla]

Less expensive option to have BrianK do the module. But my money is on the steering rack itself. For that you will need to pull it out and send it to Charles at NSX Rack Repair. Code 22 if memory serves has to do with the torque sensor and that is inside the steering rack. Good luck.

 

[emdoller]

Less expensive option to have BrianK do the module. But my money is on the steering rack itself. For that you will need to pull it out and send it to Charles at NSX Rack Repair. Code 22 if memory serves has to do with the torque sensor and that is inside the steering rack. Good luck.

Thanks. I sent the module to Brian. Hope this solves it. I’ll post back once I get the EPS module back and installed.

 

[Old Guy]

If you check the SM there is a whole pile of things that can cause error code 22. However, the most common issue is the relays in the controller. Kaz covers this in pretty good detail on his blog. The actual rack motor and the torque sensor can also be the causes.

Those photos from @triple18s are interesting (what year is your car?). Given that the rubber boots have spring retaining clips I would expect them to be pretty water tight unless they had not been pushed fully on during some previous maintenance or the boot has cracked. Might be worthy of a visual inspection and if required, cleaning and coating with silicone grease to prevent issues.

 

[emdoller]

Thanks. It’s a ‘95. I haven’t checked the rack connection yet but will hopefully get to it soon. Given it’s a 18k mile car, never driven in rain in CA, I doubt it’s that but will check. I don’t want to drive up in ramps given I took the EPS unit out. May be ok but worried about all the disconnected wires.

 

[emdoller]

Good news. Brian K received my EPS module and confirmed it has the common failure. What’s interesting for me is that the failure is time dependent vs usage given my low mileage. Expect to have it back in a few days.

Ed

 

[Wild Turkey]

Awesome! With many of the electronic failures, it is the capacitors failing and/or spilling acid onto the circuit boards, causing disconnects. @Heineken has some AMAZING repair threads. The capacitors have a lower life in hot and/or humid environments, but not as related to miles driven.

Lots of the early boards had capacitors rated for only 30 year average life I believe, & we're past that for most NSX's out there. Some of the newer cars used longer life/higher temp caps, perhaps around 1999-2000 onward, depending on the specific component, but no-one knows exactly when each component was upgraded. @Briank said my 2001 ccu was good, but speaker amps had old caps.

Frustrating that the cost to put in way better caps from the get-go would have been a couple of dollars/car, but I think Honda just didn't have experience building cars for collector timeframes. It'll go a million miles if you can do it in a decade or so. Even so, it's amazing how many of them are still on the road and functioning well considering their complexity, especially compared to other cars manufactured at that time.

 

[Old Guy]

Good news. Brian K received my EPS module and confirmed it has the common failure. What’s interesting for me is that the failure is time dependent vs usage given my low mileage. Expect to have it back in a few days.

Ed

The common failure? The common failure in the EPS controller used to be overheating of the relays and their solder connections which is usage dependent. Capacitor failures are more of an age thing accelerated by higher temperatures. What failure did you have?

 

[emdoller]

Not exactly sure. I assumed it was relay related given everything I’ve read. I’ll email Brian.

 

[emdoller]

Awesome! With most of the electronic failures, it is the capacitors failing and/or spilling acid onto the circuit boards, causing disconnects. @Heineken has some amazing repair threads. The capacitors have a lower life in hot and/or humid environments, but not as related to miles driven.

Lots of the early boards had capacitors rated for only 30 year average life I believe, & we're past that for most NSX's out there. Some of the newer cars used longer life/higher temp caps, perhaps around 1999-2000 onward, depending on the specific component, but no-one knows exactly when each component was upgraded. @Briank said my 2000 ccu was good, but speaker amps had old caps.

Frustrating that the cost to put in way better caps from the get-go would have been a couple of dollars/car, but I think Honda just didn't have experience building cars for collector timeframes. It'll go a million miles if you can do it in a decade or so. Even so, it's amazing how many of them are still on the road and functioning well considering their complexity, especially compared to other cars manufactured at that time.

Agree. It’s awesome we have people who know how to help keep these cars on the road. Great community.

 

[Heineken]

Awesome! With most of the electronic failures, it is the capacitors failing and/or spilling acid onto the circuit boards, causing disconnects. @Heineken has some amazing repair threads. The capacitors have a lower life in hot and/or humid environments, but not as related to miles driven.

Lots of the early boards had capacitors rated for only 30 year average life I believe, & we're past that for most NSX's out there. Some of the newer cars used longer life/higher temp caps, perhaps around 1999-2000 onward, depending on the specific component, but no-one knows exactly when each component was upgraded. @Briank said my 2000 ccu was good, but speaker amps had old caps.

Frustrating that the cost to put in way better caps from the get-go would have been a couple of dollars/car, but I think Honda just didn't have experience building cars for collector timeframes. It'll go a million miles if you can do it in a decade or so. Even so, it's amazing how many of them are still on the road and functioning well considering their complexity, especially compared to other cars manufactured at that time.

Capacitor failure is an interesting technical topic. While seal failure and leakage are well known cases, the PCBs in the NSX are affected very differently. The ones in the engine ECU seem to last forever while others fail very early, all of them rated for 105 °C and well known brands. I'm still thinking there are additional factors involved besides temperature and lifetime - maybe chemicals used during PCB production and cleaning - or maybe I'm simply wrong

 

[Old Guy]

Capacitor failure is an interesting technical topic.

Indeed, wet electrolytics are a particularly interesting topic.

There was a capacitor plague which was a design flaw causing premature failure in electrolytics. Nichicon, Rubycon and maybe Matsushita and Elna were affected. There was a formula change in the electrolytics in the '80s going to a water based electrolyte that did not go well. The exact period of this production problem is unclear (or the parties are not sharing it); but, the Japanese vendors probably had the problem fixed some time in the '90s. However, it appears that industrial espionage resulted in Rubycon's electrolyte formula being stolen and either the old formula was stolen or there was an error in copying the new formula which resulted in a second capacitor plague in the late '90s. This particular detail is anecdotal since there is no formal legal / documention trail related to the purported industrial espionage. Probably falls into the steal a bad / incorrect design, your bad; but, no prosecution because that just shines a brighter light on the original design problem. Most of these second wave failures were lower cost 'off-brand' capacitors used in consumer electronics and PCs originating from Taiwan.

The capacitor plague failure was typically a pop the can top failure on capacitors that were running closer to the design limits; but, seal failures were also attributed to the problem.

It is possible that some of the electronics on the NSX got caught in the tail end of the first capacitor plague. In addition to environmental conditions, this could be a partial explanation for the high variability around the failure rate. I preemptively replaced the electrolytics on the CCU from my 2000 which was a bit of a waste because none of the capacitors were showing any sign of deterioration. Also, most of the originals were 105C, not 85C capacitors which might represent a production change. When I had my door apart a couple of years ago I had a quick look at the door amps and they showed no sign of capacitor leakage. As I recall, the capacitors that came out of the CCU were mostly / all Nichicon. I didn't check to see where Bose sourced their capacitors.

There is another interesting age-out feature associated with oxidation of the aluminum electrode that occurs when the capacitor is not energized (in storage or not in use). You can find discussion of this if you look up reforming electrolytic capacitors. The oxidation ageing process does not occur when the capacitor is energized so extended periods of non use might actually contribute to earlier failure. You would have to analyse the design conditions to see whether the operating conditions are correct for the capacitors to reform themselves 'in use'.

As a final note about ECUs. Search around and you will find that the Mitsubishi 3000 is noted for capacitor failures which extended to the ECU. I didn't search around to find out whether there are other cars of this vintage suffering for capacitor related ECU failures.

 

[emdoller]

I received my EPS module from Brian. It’s been installed and although I’ve only driven it a few miles, no EPS light. Prior to this I couldn’t make it out of my driveway without it turning on even after removing battery cables. Looks like this was indeed the issue.

 

[Old Guy]

Excellent. What did Brian do? Relay replacement?

 

[emdoller]

Excellent. What did Brian do? Relay replacement?

Not sure but I believe that’s what it was.