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Discussion Starter #1
Hi folks,

I'd need some advice from the real old Hyundai experts:

After I've overhauled my Y3's front suspension/steering (all joints, wheel bearing and strut mount) the car drives well but the ABS fails (SRI on).

When removing components I did not mess with the wheel sensors but left them in place, disconnected the cable in the well.

First thought I had was cracked cable that my have suffered from the wheel bearing replacement. Since there was 0% chance that I'd get the sensors out without destroying them and having to buy new ones, I substituted the cables (except for the two ends carrying sensor & plug ...) with some high quality, hi flex polyurethane cable of similar gauge.

It passes the self test after ign. on but the SRI goes back on after a greatly varying timespan of seconds up to minutes.

I believe I can exclude sensors and wiring since:
- it passes static self test (so wiring basically ok)
- SRI goes back on after some time even if not driving (so unlikely to be a signal problem).

I had the ABS ECU blink the codes to me and it stated:
62 sensor left front open
63 sensor right front open
72 sensor right front signal jump
56 battery voltage low
42 fail safe relay open

I believe 62,63,72 are due to sensors disconnect during work and maybe an actual cable problem.
56 is hard to believe since the tolerable range is 9-16V and my battery is still quite good (~11.5V @ start/crank)

42 is the real concern.

I checked that relay and found visibly worn contacts but on the bench the relay still worked.

However I've ordered a replacement: Bosch 0 332 204 001 has the same pinout and specs as Hyundai 95210-29100 (6 Volts coil !) and costs 1/3.

Now the question: For further debugging I'd like to clear the codes (since some of them are apparently historic) but I can't connect to the ABS ECU with my scantool (Autoboss V30).

Is there an easy way to clear them without the scan tool ? Battery disconnect ? Honda method (short L-line like for blinking but step on the brake pedal while turning on Ignition, then follow the SRI blinking with the foot on the pedal 2x) ???

Anyone ?
 

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Discussion Starter #2
Let me update on that:

I've replaced both relays but the result was still the same.
Then I noticed that the failure also occurred when putting the car into/out of gear.
Closely inspecting the relay box surroundings I found part of the relay harness contacting/rubbing on the upside of the A/T housing thus getting some impact and vibrations induced from there.
Using a zip tie I removed this condition.
First it looked very promising, the ABS was ok (and worked fine when I hit the brakes on an icy road) for almost a full day until the light came back on.

Looking at the cable rub mark on the A/T it became obvious that this condition has existed for quite some time. Potentally the cable got damaged.
I'll keep investigating in this direction.

Unfortunately I did not find a way to clear the codes. When I blinked them out later I still got the same set reported as above.
 

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I 'fixed' a similar ABS cable rubbing on my Explorer with self-fusion rubber tape.
In my case the wires inside where also cut, but I solder them back together and applied heat-shrink tubes on each of them.
 

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Discussion Starter #4
Next chapter:

Installed a camera to watch the SRI light while I was trying to recreate the error by knocking on the relay block, bending cables. Nothing. No fail.

I have meanwhile bought another ABS ECU on E__y just to try that out. 20$ plus shipping, not a huge investment.
I hope that one will also communicate with my scan tool since that ECU is from a 98 model while mine is an early 96.
Also measured various pins on the ECU harness like speed sensors, brake switch input, relay coil resistance ... all in spec.

Mistery ...
 

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Discussion Starter #5
Let me continue my monologue:

'New' ECU box is dead. One of these parts that 'worked until removed from donor vehicle' ...
Doesn't pass self test (as my original one does) and does not go to error blink mode on shorting L-line (dito).

Of course it doesn't talk to my scantool either ...

One advantage that all had: While my original box was out of the car it 'forgot' all the error codes. When I succeded to reproduce the problem with it back in place (just put car in gear, R or D from N or P) I had it blink codes to me. And there were now only two:

67 RF sensor short to ground
72 signal jump RF

So I remeasured the F sensors and really: while the LF has no continuity to the steering knuckle the right one has.

So why doesn't it fail during self test ? The explanation is simple:
There is no continuous ground connection to the knuckle & strut. The assembly has floating potential (since isolated by ball joint plastic and strut mount rubber) and only occasionally (e.g. at the shift shock) gets grounded via wheel bearing, driveshaft and tranny.

The situation can easily be reproduced:
ign. on, self test success (SRI off), ground (e.g.) wheel flange to any grounded part nearby by some piece of wire and immediately the failsafe/modulator relay can be heard falling (=SRI on).

Since the issue immediately started after the new wheel bearings got installed I can only assume that the one sensor was struck during bearing replacement at my Hyundai dealer.

Now the challenge will be to get the old sensor out and to source a new one here for a reasonable price.
 

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Sometimes the obvious is so easy :)
 

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Discussion Starter #7 (Edited)
Some pictures attached to illustrate what 17 years of rusting does to the sensor. Was quite some work to get it out and then get the bore back to the initial diameter to accommodate the new one without the need for a hammer ...

Now waiting for the new sensor to arrive. Ordered one for the EF which appeared to fit in terms of coil parameters, pole piece and flange orientation (but may need some cabling modification). 35€ +p&p.
For sensors for the Y3 I found only offers from over 100€ up.
Try the other solution first.

Meanwhile also got my money back on the faulty ECU but kept the part. May open it just to see what's inside.
 

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Discussion Starter #8
Fitted EF-Sonata wheel sensor (aftermarket part).
Cable harness mod, a little filing at the flange to make the screw go in, a thin washer for the correct airgap - and finally I have ABS again.
 

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