ABS light -- 2004 Santa Fe

I have a 2004 Hyundai Santa Fe with a 3.5L engine, AWD (4WD), with front and back ABS disk brakes, and 93,800 miles. (This is the same vehicle that I
had to oil pressure light and oil sludge issues with a few weeks ago. The problem started after all of that was resolved, but I doubt that the two things are related).
The ABS light has recently started coming on, but only in certain circumstances. The ABS light only comes on after I have been driving for a while (maybe 30+ minutes or so) on an Interstate highway or other high speed road. Usually, once it comes on, it stays on until I reach my destination. Then after I turn off the car and wait a while, the ABS light does not come back on when I restart the car. It never comes on when doing local lower speed driving, even if I am driving locally for 30, 40, 50 minutes or more.
I had a flat tire fixed and tires rotated about 6 weeks ago and they mentioned then that the back brakes are getting worn and need new disks and rotors. About a week ago, I had the brakes checked all around, and they said the front brakes are fine but the back brakes did need new disks and rotors, so I had that done. The ABS light problem happened before getting the brakes repaired, and it continues to happen after the brake repairs were done.
My hearing isn't the best, but people riding in my car say they can hear a slight possible wheel bearing and/or clicking sound coming from the right rear wheel area while riding. I don't hear it, but they say the sound does not seem to increase or decrease with changes in the speed of the car. I mentioned noise issue when I had the brakes checked and the rear brakes repaired. They checked the wheel bearings and couldn't find anything wrong with them and no play in the wheels etc.
Here's my question: How would a dealership or auto repair place go about trying to find out what is causing the ABS light to come on? I am guessing that they can hook the car up to a computer and look for the error code, but wouldn't that only work if and when they can get the ABS light to come on?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
TomR wrote:

Just an update -- It has been almost a month since I first posted this and the ABS light only came on 2 or possibly 3 times since then. It only happens as described above (on some longer high speed trips) but very infrequently. The breaks seem to be working fine, even during those few times when the light comes on. So, for now, I am not going to bother taking it in to be checked. If I find a way to reliably reproduce the problem and get the ABS light to come on at a time when I can get a mechanic or dealership to hook it up to a computer, I'll have it checked then.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 7/25/2012 3:10 PM, TomR wrote:

Just like with the check engine light, when the ABS light comes on a diagnostic code is stored in the ABS controller. Even after the light goes out, the code remains in memory and can be read with the proper scan tool. Note however, that although anyone with a generic OBDII reader can access engine codes, the scanners to retrieve ABS information are not as readily available. An independent shop might be able to do it if they have the right equipment, otherwise it's a trip to the dealer. Some vehicles allow you to connect some plugs together under the dash to put the system into a diagnostic mode and read the codes by flashing the light, but I don't know if Hyundai has this capability.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
TomR wrote:

Codes are stored. Have a dealer read the ABS codes. Odds are that a wheel sensor is bad or has broken wires.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Paul in Houston TX wrote:

Thanks Paul in Houston TX and Mulder. That's good to know. I didn't realize that the error code would be stored. What I will probably do is just wait until the ABS light comes on again and then take it to a dealership soon afterward and have them read the ABS codes.
From what I have been reading, it does sound like a wheel sensor problem, and most or the online info suggests what you said -- that it could be bad or broken wires. I also saw info somewhere that said it may be possible for dirt or debris (or ice or snow, except that it is summer here) being in the area where the sensor reads the wheel turning.
From what I read, reading the ABS error code should identify which wheel is having a problem.
But, again, knowing that the dealership can read the stored error code even after the ABS light goes out is a big help.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

The dealer will probably charge you a diagnostic fee to read the code. Auto Zone (and other places like that) does it for free as they hope to sell you the parts.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 7/26/2012 9:52 PM, Ed Pawlowski wrote:

Autozone can only do an OBDII scan for free to read engine codes. They can't read other codes such as ABS, airbag, body module etc. that require different (and often proprietary) scan tools.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
snipped-for-privacy@x.files wrote:

Thanks. I had read that before somewhere (maybe on this forum). Maybe the next time that I am at AutoZone I'll ask them just to be sure. But, I think you are right about AitoZone not being able to read the ABS light codes.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.