ABS/ASR Error: Troubleshooting & Solutions

Hello colleagues,
'I have an ABS/ASR warning light on my dashboard (two lights) since I replaced the crankshaft position sensor. To narrow down the cause (broken wire, interruption, or dirty sensor/ring), here are my questions: Will turning off the ignition reset the warning light in the instrument panel? If so, after restarting the engine, the lights should go out and only reappear after a short distance if the error is caused by dirty ABS sensors. Conversely, if the error is due to an interruption in the wiring to the ABS sensor (or another constantly present fault), the warning light should not disappear even after restarting the engine - is that correct?'
Best regards, Stephan.

I hope it's exactly as you described.
Yesterday, I also had a problem with the brakes – I'm not sure if it was the ABS or something else – but it wasn't there when I started the car again.

Hello Stephan!
The ABS warning light illuminates as follows:
-When you turn on the ignition to check this lamp, it should not be illuminated due to a defect. If it is lit, the ABS system is deactivated.
-During this check phase, the control unit performs a quick test, checking all sensors and actuators. If a signal is missing due to a broken wire or a faulty sensor, the warning light will not turn off -> no ABS functionality.
- If the lamp turns off after 2-4 seconds or when the engine starts (depending on the manufacturer), but then immediately comes back on when a speed of more than 7 km/h is reached, then the sensor itself or the cable connection are usually not the cause. Instead, the problem may be due to a dirty contact ring or, in the case of rear-axle brakes up to Golf III / Passat 35i, a defective or poorly adjusted wheel bearing. These errors are normally stored, but reset on the next start.

I hope you can make sense of this.

Best regards,

Dominique[/list].

As far as I know, my ABS system (in a Golf 3 with a Mark 20) also measures the voltage available to it.

Below 10 volts, the indicator light turns on (and presumably, the ABS system also stops working).

It's nice to see when you turn on the ignition in a TDI and wait.
- After 2-4 seconds, the ABS light should turn off.
- When starting, the voltage drops and then immediately recovers.
- The lamp turns on and then turns off again after another 2-4 seconds.

Okay, please provide the German text you would like me to translate into English. I will only provide the translation.

@Dieselmartin
'That's true; almost all control units react to undervoltage with an error message. But below 10 volts during starting... either the battery isn't really fresh anymore, or you have such a high resistance somewhere on the way to the starter motor that so much voltage is lost that this effect occurs when starting. In my case, it's not like that. However, normally another problem would occur with the TDI in that situation... A worn-out battery or a starter motor rotating too slowly due to insufficient power supply are also reasons for starting difficulties that are often discussed, and which you can only really understand as an insider. (By the way: my battery is as old as my tractor, almost 8 years... let's see how much longer it will last... )'
Therefore, I left this potential source of error in the ABS out of consideration; it should be the lesser evil if the engine is only starting with difficulty.

So, I still have the original battery in it.
Trekker and Batt are just over 8 years old.

I never had any starting problems. Once, it started a little harder than usual, but that was preceded by a warning sign: the wastegate control valve (N75) was making noise.

The ABS light illuminates with every start, and it has been doing so since I've owned the vehicle (which is about 1.5 years).

I still have a 63Ah battery. I could try connecting it in parallel (or even two more batteries from my T3, if necessary) to see if that would silence the ABS system during engine start.

Sure, here is the translation of the text from German to English:

"m" translates to "male" in English.

@stephan

I think it's probably due to a dirty print bed.

It has been discussed several times here in other threads!

@Dieselmartin
Then consider yourself lucky if only the lamp comes back on when starting the engine and otherwise everything is fine. Perhaps your ABS control unit is just a very sensitive device...

Best regards,

Dominique.

Hi,

"Sometimes, the ABS warning light comes on for me again when I start the car, and it's been doing that since the beginning (the car and its battery are now just over 2 years old)."

When starting, the voltage on the voltmeter drops to around 10 volts, usually slightly above that, but sometimes also slightly below.

I think it's mainly related to the preheating time, because that also puts a significant strain on the battery before starting (in my case, it drops down to 11.3 volts, which I measure at the cigarette lighter socket), and if the car has been standing overnight, the voltage can even drop below 10 volts during startup.

Best regards,

January.

Hello,
Thank you for your help. I will let you know once I have the solution.
Best regards, Stephan.

Dirt on the sensor and an excessive distance to the encoder disc were the cause. It's working again now. Actually, it has been working for a while, but I unfortunately forgot to post about it.