lost power steering today, EPS light on

Joined
25 May 2020
Messages
41
Location
NY Hudson Valley
have only had the car (NA2) a week or so and it has been fine.... today I started the car and the EPS light stayed on and steering was very heavy... obviously no power assist.

I find it strangely coincidental that I had just hooked up a battery tender (removing the terminals in the process).

Any suggestions? I was surprised there isn't a corresponding fuse which was the first thing I would check.

thank you!!!
 
found the great thread on this subject and read thru everything. battery is good. connections all good. i pulled the fuse for the clock and now i've got a check engine light on too
 
Re-check your battery connections
 
If the unit has to come out, there is a member who does component level repair on the box. I believe the quick fix requires replacing diodes. The unit is located under the carpet in the passenger side foot well. I sent my unit to two different vendors for repair and both were unsuccessful. The second vendor was located in Jacksonville Florida and charged me $500. The repair did not work. Despite a written guarantee the company would not refund my money. I finally successfully reversed the charge on my credit card. I ended up purchasing a new unit from Acura. The part was on back order for a number of months. The units are not the same throughout the 1991 to 2005 model run, so be careful if you purchase a used unit. Try the usual methods of repair before purchasing a new unit. I was lucky, I paid $1,600. My local Acura dealer wanted twice that price. I wish the news was better. Good luck. Jerry
 
So there is a way to test the EPS brain and see whats going on. Somewhere in the manual.
What Check Engine Code are you getting?

Unfortunate, but curious if seller who sold you the car knew and reset before sale?
 
fyi, car is a 2002 model year.... battery connections are all tight and clean. pulled clock fuse- did not work..... after pulling and re-inserting the fuse my check engine light is on. EPS light is still on and no power assist. Will get an OBD2 scanner on it later today. I find it impossible to believe that my disconnecting the battery to put on the tender quick release adapter didn't cause this.....way too coincidental. A few quick questions please (and thank you!):

1) should I be pulling the clock fuse when the car is running?
2) all the mention of error codes... are we talking codes taken from the OBD2 port or codes taken directly from the EPS controller?
3) is it OK to drive the car without EPS?
 
Old electronics fail..I had my 96 fail like yours 5 years ago got the module replaced...
 
My EPS system failed when I disconnected the battery. When I reconnected the battery, the EPS light was on and the PS did not work. Yes, you can drive the car as is, it will not hurt anything. Jerry
 
thank you

My EPS system failed when I disconnected the battery. When I reconnected the battery, the EPS light was on and the PS did not work. Yes, you can drive the car as is, it will not hurt anything. Jerry

Jerry, thank you, are you saying that your EPS unit actually failed and had to be repaired as a result of disconnecting the battery? thanks
 
fyi, car is a 2002 model year.... battery connections are all tight and clean. pulled clock fuse- did not work..... after pulling and re-inserting the fuse my check engine light is on. EPS light is still on and no power assist. Will get an OBD2 scanner on it later today. I find it impossible to believe that my disconnecting the battery to put on the tender quick release adapter didn't cause this.....way too coincidental. A few quick questions please (and thank you!):

1) should I be pulling the clock fuse when the car is running?
2) all the mention of error codes... are we talking codes taken from the OBD2 port or codes taken directly from the EPS controller?
3) is it OK to drive the car without EPS?

With a little searching on Prime you will find a link to a .pdf version of the 1997-2005 service manual. You will find the procedure for retrieving error codes using a scanner and using something called the service check connector. The service manual does not call for pulling the clock fuse while the engine is running to reset the codes so I would not do that.

When you pulled the clock fuse you erased all stored error codes. You may (or may not) have to wait a bit for the error codes to re appear depending on what causes the error codes.

The NSX is a pre CAN bus car. The various control modules are loosely integrated which means that the OBDII port only reports on OBDII required codes and some specific manufacturer codes ( some transmission problems if you have an automatic). The other modules such as ABS, EPS, TCS and SRS which have 'status indicator lights' on the dash have there own internal error checking and reporting schemes. In order to access the error codes from these systems you need to short the service check connector ( as described in the service manual) and then count the blink sequence on the indicator light for the affected system. The service check indicator will also trigger the ECU to start reporting ECU (OBDII) error codes via blinking the CEL. If other modules have stored error codes (they don't always result in the lights coming on right away) these devices will also start reporting their error codes - everything can start blinking.

Counting the blinks can be confusing. You need to consult the service manual in order to interpret the blinks to determine the code, particularly if there are multiple stored codes. The ECU codes can be read from the CEL without the use of an OBDII reader; but, the code numbers are larger and more of a hassle to read. An OBDII scanner is much easier; but, you have no choice but to count the blinks for the EPS. The service check connector is tucked up in the passenger side footwell, sometimes hidden behind the top edge of the carpet. You may need to remove the cover under the glove box to find it. There is a recent thread on Prime asking specifically about EPS codes which covers the mystery of finding the SC connector. Sometimes the SC is right out in the open and easy to find.

Others have reported no problem with driving the car with a failed EPS other than requiring a lot of steering effort.

Once you are able to retrieve the stored codes you will get a better handle on what the potential problems are.

There are 'fuses' for the EPS system including a big-ass 50 or 60 amp rack motor fuse. Its unlikely that fuse will have blown. The section of the service manual on the EPS has a diagram with all the fuses.

I find it impossible to believe that my disconnecting the battery to put on the tender quick release adapter didn't cause this

I tend to agree. What is the quick release adapter? Is it permanently installed on the battery? If so, I would remove it an re try with the original battery clamps on the posts. Double check your battery post connections. On my 2000 the clamps and posts looked just fine; however, I discovered that even with the clamp bolts tightened to the max I could easily twist the clamps on the battery post. The OEM clamps are 'minimalist' and heavy handed mechanics can deform the clamp rendering it useless and requiring replacement of the clamps on the cables.

I don't drive my car in the winter and it rains infrequently here so corrosion has not been an issue for me. However, if your car was winter driven or exposed to a lot of moisture the ground connections including the battery - cable can become compromised. Checking those ground connections could be on a potential check list. You can get a fairly good idea as to the condition of the battery and the wiring / connections by measuring the voltage during cranking. Don't rely on the dash voltmeter because it won't indicate problems with the wiring. An old school 'meter' style voltmeter is best or a digital voltmeter with a fast update time (budget multi meters generally won't cut it). Connect the voltmeter to the jump start terminal in the engine fuse box. Pre start voltage should be around 12.2 volts. While you crank the motor have somebody watch the voltmeter and record the lowest voltage during cranking - just before the motor actually starts. If the voltage is above 10 volts your major cables and the battery are likely OK. If less, then you likely have an aged battery or compromised wiring. Note that the major cables can be OK; but, you can still have a problem on the direct wiring to the EPS controller (although less likely).
 
Eps

The little plastic plug on my brake light broke and my tail lights were stuck on. I was at work, and I disconnected the battery. Upon reconnecting the battery, my PS was not working and the EPS light was on. I cleaned the grounds etc. I took it to my local dealer who happened to have another same year NSX in for repair. They swapped the box from the other car to mine and the PS worked. I sent the module out three times to two different repair people and three times it failed. I replaced it with a new unit and all is well. Jerry
 
With a little searching on Prime you will find a link to a .pdf version of the 1997-2005 service manual. You will find the procedure for retrieving error codes using a scanner and using something called the service check connector. The service manual does not call for pulling the clock fuse while the engine is running to reset the codes so I would not do that.

When you pulled the clock fuse you erased all stored error codes. You may (or may not) have to wait a bit for the error codes to re appear depending on what causes the error codes.

The NSX is a pre CAN bus car. The various control modules are loosely integrated which means that the OBDII port only reports on OBDII required codes and some specific manufacturer codes ( some transmission problems if you have an automatic). The other modules such as ABS, EPS, TCS and SRS which have 'status indicator lights' on the dash have there own internal error checking and reporting schemes. In order to access the error codes from these systems you need to short the service check connector ( as described in the service manual) and then count the blink sequence on the indicator light for the affected system. The service check indicator will also trigger the ECU to start reporting ECU (OBDII) error codes via blinking the CEL. If other modules have stored error codes (they don't always result in the lights coming on right away) these devices will also start reporting their error codes - everything can start blinking.

Counting the blinks can be confusing. You need to consult the service manual in order to interpret the blinks to determine the code, particularly if there are multiple stored codes. The ECU codes can be read from the CEL without the use of an OBDII reader; but, the code numbers are larger and more of a hassle to read. An OBDII scanner is much easier; but, you have no choice but to count the blinks for the EPS. The service check connector is tucked up in the passenger side footwell, sometimes hidden behind the top edge of the carpet. You may need to remove the cover under the glove box to find it. There is a recent thread on Prime asking specifically about EPS codes which covers the mystery of finding the SC connector. Sometimes the SC is right out in the open and easy to find.

Others have reported no problem with driving the car with a failed EPS other than requiring a lot of steering effort.

Once you are able to retrieve the stored codes you will get a better handle on what the potential problems are.

There are 'fuses' for the EPS system including a big-ass 50 or 60 amp rack motor fuse. Its unlikely that fuse will have blown. The section of the service manual on the EPS has a diagram with all the fuses.



I tend to agree. What is the quick release adapter? Is it permanently installed on the battery? If so, I would remove it an re try with the original battery clamps on the posts. Double check your battery post connections. On my 2000 the clamps and posts looked just fine; however, I discovered that even with the clamp bolts tightened to the max I could easily twist the clamps on the battery post. The OEM clamps are 'minimalist' and heavy handed mechanics can deform the clamp rendering it useless and requiring replacement of the clamps on the cables.

I don't drive my car in the winter and it rains infrequently here so corrosion has not been an issue for me. However, if your car was winter driven or exposed to a lot of moisture the ground connections including the battery - cable can become compromised. Checking those ground connections could be on a potential check list. You can get a fairly good idea as to the condition of the battery and the wiring / connections by measuring the voltage during cranking. Don't rely on the dash voltmeter because it won't indicate problems with the wiring. An old school 'meter' style voltmeter is best or a digital voltmeter with a fast update time (budget multi meters generally won't cut it). Connect the voltmeter to the jump start terminal in the engine fuse box. Pre start voltage should be around 12.2 volts. While you crank the motor have somebody watch the voltmeter and record the lowest voltage during cranking - just before the motor actually starts. If the voltage is above 10 volts your major cables and the battery are likely OK. If less, then you likely have an aged battery or compromised wiring. Note that the major cables can be OK; but, you can still have a problem on the direct wiring to the EPS controller (although less likely).

great review as always....and I appreciate all the typing you do!
 
With our NSX, EPS is not on the OBD2 stream so please use the SCS blue 2pin connector method and count the flashing lights.
You can refer to this; http://www.nsxcb.co.uk/showthread.php?9229-How-to-read-the-error-code

If not sure, just follow the above procedure and upload the video clip from the point you turn the IGSW into P2 ON position.

In answering your questions;
1) Don't pull the Clock fuse until after you read the code or took the video.
Once confirmed the code, reset it by pulling the Clock fuse without running the engine and IGSW in OFF position.

2) For EPS, you can't use OBD2 on our NSX.
Please use the SCS blue 2pin connector method as above link.

3) As long as there is no mechanical issue, you can drive without the EPS.
However, if the EPS warning light was triggered due to EPS rack commutator getting heavy rust because of rackend boot separation allowing water getting inside, it could lockup the rack.
Without running the engine, lift the frontend of the car and turn the steering wheel both way.
You should hear faint/smooth rolling noise and this is normal.
However, if you hear loud squeaking noise or rattle, you may need sending the rack for refurbishment.

Kaz
 
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well I "fixed" it..... pulled the clock fuse with the car OFF and waited 30 seconds. back in business. I am hoping this was a one time thing with the battery being disconnected. thanks again guys. too bad i've already had 4-5 beers while trying to sort this out and can't take the car out now. :-(
 
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great review as always....and I appreciate all the typing you do!

After 3 or 4 cups of fresh ground dark roast, my fingers are running on a bit of a caffeine induced frenzy. At least this time I think they managed to stay on-topic.
 
well I "fixed" it..... pulled the clock fuse with the car OFF and waited 30 seconds. back in business. I am hoping this was a one time thing with the battery being disconnected. thanks again guys. too bad i've already had 4-5 beers while trying to sort this out and can't take the car out now. :-(

That is good, if it stays fixed. Unfortunately, the EPS trouble indication seems to have a way of returning shortly after you take the car for a drive and use the EPS. However, you may be the charmed one and it goes away and stays away.
 
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