Sonata (2000), ABS and TCS Off lamps both on. Car drives and brakes normally.

Can anyone give me a techical reason why the 'ABS' and 'TCS Off' indicators have both become permanently illuminated on my Sonata V6 / 2.5 (2000).
The car seems to drive normally.
I'm an experienced electronics engineer so happy to do some serious diagnostics.
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It will drive normally, but if you need the abs, it won't be there. The brake systems are designed to function in normal mode if any electronics fail.
You may have a bad wheel sensor or some other malady. Hook up the diagnostic computer and get the code. Many auto parts will do it for you.
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Fail-safe would make sense. I would like to understand the common elements of the ABS and the TCS that would cause my 'TCS-OFF' and 'ABS' indicators to both become permanently illunmninated at the same time.
The wheel sensor you mention - Could you tell me roughly where to locate it so I can trace its wiring ?
Do you know what technology the sensor uses; magnet/hall-effect - reed switch!!
THanks

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The ABS and TCS use some parts in common. You can get more information as to location and so forth by signing up for a free account at www.hmaservice.com You need IE and may have to download a free viewer from Adobe to see the drawings.
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Typically, it's part of the wheel bearing. Easy to see - there is a wire running to the bearing. Magnetic in nature, and it just creates a square wave pulse. The common elements are simply the sensor. Both ABS and TCS operate using the input from these sensors, one to prevent lock up and the other to attempt to maintain proper relationship between the rotation of each tire.
The other day I picked up a nail or something in the inside sidewall of my passenger side front tire. Had to have another tire ordered in at the place where I purchased these tires. So, in the meantime, I drove around with the space saver spare mounted up there. ABS and TCS lights burning the entire time. Got the new tire mounted and poof - they were out. The space saver is a different size tire than the real stuff, so the wheel on that side is rolling at a different speed than the others. Throws the system off. Heck - even the speedo was off. It showed almost 10mph faster than what my GPS showed me traveling.
--

-Mike-
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Typically, this would be the lack of any sort of input that would cause both the ABS and TCS to not be able to operate properly. If you make a couple panic stops, you'll see that the ABS is no longer functional. Both the ABS and TCS are controlled by the same module and actuators. Since you're an electronics engineer, you can probably infer a very good understanding of how the system works by consulting the schematic at www.hmaservice.com as Edwin has suggested.
Checking individual components and wiring until you find an issue is not an efficient way to go about solving this problem. There are simply too many possibilities. Normally, I'd suggest checking the wheel speed sensor tone wheels (on the axle or wheel hub) since it's quick to do if you can get under the car. But since you don't seem to have a good idea of what you'd be looking at, that's likely a futile exercise. The place to start is to take the car to a shop capable of diagnosing the ABS/TCS system. They'll read the codes and inspect the specific items that could potentially cause that particular code. Once you know the specific problem, you're in a better position to determine whether it's a repair you'll be able to do yourself.
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Hmm, before I can put the oscilloscope on the wheel sensor signals I must get the schematic for the vehicle from HMASERVICE when I figure what my Sonata V6 2.5 (year 200) is in terms of the choice made available, vis:
Sonata EF Sonata NF Sonata Y2 Sonata Y3
Then, I recall that one of the following links leads to schematics
ETM DTC TSB
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Years 1999 to 2005 are Sonata EF. Once you choose one of the models, the page will delete all years which do not apply.
The ETM (Electrical Troubleshooting Manual) leads to schematics. DTC = Diagnostic Trouble Codes. TSB = Techncial Service Bulletin,
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Thanks for that advice.
Today, in an effort to obtain the CAN diagnostic error code I took the car to the garage only to be told by the service manager that hooking-up their diagnostic device would amount to 'at least an hour's work' - I didn't get the code today
I have noticed that my TCS-OFF' and 'ABD' indicators only illuminate after the car has moved a few metres so there is perhaps a good indicator of a movement sensor input going on here.
I obtained the schematics for the TYCS/ABS and once I have located the ABS module I will make some diagnostic measurements.
Was interested to read one respondent refer to the toothed wheel part of the inductive pickup as a 'tone wheel' - a fellow Hammond player I thought! Correct tech!
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This afternoon I located the four wheel inductive pickups but their wiring disappears into a loom so I haven't located the ABS electronics module yet. Any suggestions of where it is to be found? I figure that this module is thelogical place for me to check all the wheel sensor signals.
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Have you created a user account on the free Hyundai web site with all of the manuals, diagrams, etc. yet, as was suggested to you in reply to your initial question? You can flog yourself all day long, trying to muscle through this, or you can cheat and use some of the documentation that is provided to avoid a lot of that frustration.
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Yes, I registered with that site some years ago and have been using it tho' my Browsers (Firefox and IE8) are giving me so much trouble with Adobe's SVG format I'm finding it easier to trudge through the hard way!).
I haven't managed to get it to show me the whereabouts of the ABS module, Can you tell me?
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You'll find the ABS/TCS module on the right side of the car near the firewall above the alternator.
The fact that your car must move for the warning lamps to illuminate suggests that it's not a purely electrical issue, i.e. a resistance check won't turn it up. It could be a faulty signal-- are all your tires the same size?-- or a performance-test issue. The ABS/TCS performs a quick self-test shortly after the vehicle begins moving.
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I am pretty sure I found it. A metal box with a group of brake pipes leading from one side, a 10cm diamter black motor visible to another side of the assembly and a substantial mutiway loom connector with a cunning retaining mechanism.
I would like to get the pinout for that connector so I can check the various power and sensor signals are getting that far.

I measured about 3.5k ohms on the front/right and front/left sensors but despite fishing about the boot/trunk, haven't managed to find those in-line connections yet.
I checked the tyres, they seem ok. I guess the ABS/TCS computer has to allow some amount of wheel speed discrepency, at least for a short period, or perhaps at low speed. Otherwise they would set off the alarm on a tight radious manouvre such as parking, for instance?

Ah, I wonder if that is what's happening, and that test is failing and bring on the 'TCS OFF' abd 'ABS' indicators?
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Success!
All the wheel sensors are two wire devices and all have in-line connectors just after their cable gromits bring their cable through the body to the inside of the vehicle. The rear connections are pretty hard to get at but accessed by folding down the rear seat back and unscrewing a two part flatish panel that runs along the back shelf and descends down on either side: This reveals the connections.
I measured each sensor at just under 1.4k ohms.
So starting the car and a short test drive and the ABS indicator is no longer illuminated.
Its looking to me like a connector/contact related problem. If I had to guess I would suggest the visible corrosion-like residue on the multiway connector fitted to the ABS control computer / actuator.
Thanks to all on this helpful folk on this group for their assistance.
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This is not a good development.
There should be a seals in the ABS connector to keep water and contaminants out of the terminals. Once corrosion sets in, it's difficult to keep it away permanently. If this is indeed corrosion, try to clean it off as well as possible and make sure the seals on the connector and wires are in good condition.
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