Hello everyone, it has been a while since the abs warning light has come on in my s4, I have checked the resistances of the wheel sensors on the respective pins of the multiple connector of the abs brain getting about 1000 ohm in all 4, there is One thing that I have observed, when the car starts to move I hear for a moment like the hum of a relay and I don't know what it could be, I have checked the fuse and relay, bypassing the latter obtaining the same result so I have discarded the Failure of the same, the system check is correct since at idle there is no warning light, there are times that the warning light flashes with the car in motion until one of the times it stays on fixed, which you think can be and How to find out? Thank you very much.

 

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nobody knows anything?

 

If your asking a question First I’m not really sure what the problem is or when the situation occurs
does the light come on when you start the car? If so replace the the relay on the CE panel

does the light come on after the car starts moving
or after a turn is made
or after hitting a bump
check Sensors at the wheels pull them out and clean them they can get filled with rust
check barrel plugs at the front fender well strut areas under the hood the plugs crumble
check ground wires at each wheel
Does the brown wire have a bad connection
Vheck the ground wires bundle in the spare tire well

 

Without the dedicated factory ABS tester, tracing and fixing ABS is amazingly difficult.

If the light always stays off until the car is in motion, you can be fairly certain that the problem is in the sensors, the wiring, or the computer.

Before I found and purchased the factory tester, we had reasonably good success removing the plug from the computer and checking the signal from each sender, independently.

And a resistance test won't do. You need to check for a signal, when moving or spinning a wheel.

 

Hello, good morning, thanks for the answers, let's see if I can clarify the problem, the Google translator you already know that it does its thing, the point is that when I start the car and it remains without moving and idle it checks all the systems and all the warning lights go off correctly, then when I start driving it sounds like a buzzing noise although the warning light remains off, then once driving the car there have been times that the abs light has come on intermittently and Lately it is fixed once it is turned on, I have tried to bypass the abs relay and nothing, the same result, abs light on, the front wiring on both sides is new, what readings should I obtain to know if it is a sensor that failure? Proven correct resistance readings at abs brain manifold connector pins.

 

Have you removed and cleaned every abs sensor
It is helpful to have Greg’s ABS testing tool as It is easy to test and fix the part that’s not working

 

And what is Greg's tool?

 

Yes, I have cleaned the sensors as well as the negatives and all their connections.

 

Broken wires in the wheel well or engine bay are typically the culprit. All 4 wires to the ABS were broken on mine. I had to pick a harness off a junkyard S4 to fix mine.

Look for broken sheeting and exposed copper strands too.

 

I have checked the wiring for continuity and it does not exist between the cables themselves or between them and the chassis.

 

This:


Bosch ABS tester

This unit plugs into the harness (replacing the computer) and checks everything, including the harness.
Intermittent problems can still take time to isolate.
Sometimes we need to drive around with the tester hooked up and monitor different wheels sensors/other functions to find the problem.
For instance, I've got a 928 here (which just came from another shop), which lights the ABS light about every 5-10 miles.....and then immediately resets the light, if you cycle the key.
Extremely intermittent....as some of these are.
Even with the tester, that could take some time (and luck) to isolate.
It would be great if the tester had a memory (which one could go back and read, in order to see what just messed up), but it is way too old for that technology.
And being just a simple mechanic, I'm way too stupid to add that function in.

 

Today I have rechecked wiring, cleaned sensors, etc. without results, I don't know what else to do to determine what the problem is and if it is a sensor or something else😭😭😭😭😭

 

This tool is fairly economical and replaces test lights, volt meters, etc:
https://www.autelsale.com/wholesale/...SAAEgKvZfD_BwE
Every toolbox needs one.

You can hook this tool onto the two wires from each wheel sensor (at the brain) and visually see the signal that is generated.
We used this method, extensively, before I found the Bosch ABS tester.

 

Is it like an oscilloscope?