ABS Sharan, year 2006, error cannot be fixed

Hello guys and girls

I've been having a problem with my ABS for about a year.

Error code: Left wheel sensor defective, mechanical failure.

Here's what has been done so far...

1. Control unit replaced.
2. Hydraulic component replaced.
3. Left wheel sensor replaced.
4. Replaced the left-hand wiring harness from the wheel sensor (including the pins from the control unit to the sensor connector).

I also checked the ABS ring, including the air gap!

I'm at my wit's end.

The problem with this is that...

The error only occurs when the engine is running. If I roll down a hill with only the ignition on, will the ABS/ESP system activate?

I used VAG-Com to check the ABS control unit.

The leftmost top value displays nothing when the engine is running. All other sensors are working normally; only the ignition sensor is showing values that are all the same.

Does anyone have any ideas?!

Sure, no problem. Here's the translation:

'Thank you in advance...'

Best regards,
Michi.

Hmmm, no ideas yet...?

Apparently, the engine or a component attached to it is producing some kind of interference that is affecting the ABS system.
I would therefore start by checking the surface roughness of the Lima.

If you don't have a way to diagnose the problem, you can simply disconnect the thick cable and the connector from the alternator and see if it works. Please make sure to insulate that thick cable very well!

Okay, so this is what I've done.

Disconnected the charging cable from the alternator to the battery and insulated it to prevent anything from happening.
Test drive... Result: ABS/ESP are working. Of course, the error message 'Generator Werkstatt' appears.

What exactly does this test tell me? Could it be that the alternator is faulty?

A thousand thanks for your answers .

What should I do next?

Best regards,
Michi

PS: Could this also be a possible cause for my increased battery consumption? The last battery only lasted for 3 years.

Congratulations on the successful diagnosis. The alternator is probably faulty... I doubt it makes sense to just replace the voltage regulator once.

Personally, I would check the large online marketplaces for used parts (I always search on www.callparts.de) and look for the part using the original part number, and try to find a used one. Otherwise, you'll likely have to pay well over €250 for a replacement.


If the alternator has a high ripple content, which disrupts the entire electrical system, a direct current component like the battery does not appreciate this ripple (which is essentially a superimposed high-frequency alternating voltage on top of what should be a verschandeln direct current). It's quite conceivable that this could cause it to fail.

Now, the deterioration of the alternator has progressed to the point where it's starting to affect various components... and it requires relatively quick action, because there will certainly be a point where certain control units will no longer tolerate the disturbances, potentially shutting down, and in the worst case, failing completely.


I think you can probably handle the installation and removal of the alternator yourself. If you need help, I can let you know what steps to take.


Greetings.

I still have a 120A alternator at home. It's weaker and from a 2001 Sharan, but I think it might fit...
I'm just not sure now whether it has a freewheel or whether my 2006 model even has a freewheel!

What do you think, should I modify these for testing?
The alternator is going to be modified right away...

Best regards,
Michi

If the other bra fits, try it on. Practice makes perfect. It's better to rent first, rather than buying outright.
You know how the freewheel works. Once the belt is removed, you'll be able to see if one is attached. If you can't replace the freewheel with a new one because you don't have the correct socket adapter, then try it without replacing it first.
hg
Herbert.

Hello again...

I've temporarily installed the alternator, but unfortunately, it doesn't have an automatic clutch (freewheel). However, it was enough for the test.

Unfortunately, the error is still there, so I've reinstalled the alternator. It has a 140A output and a freewheel function!

What and how should I proceed with my search now?

Best regards,
Michi

Strictly speaking, the designation "mechanical error" indicates that the wheel sensor is not receiving a proper signal.
That could also be due to the encoder wheel or the wheel bearing.
With the generator running, there's a slight hum on the 12V distribution. If the sensor signal is too weak, it won't be detected. When running on battery power, the hum is absent, and the signal is detected.
Is the wheel sensor close enough to the encoder ring? Is the ring integrated into a gear or a wheel bearing?
hg
Herbert.

What are the relative wheel speeds compared to each other?

Yep, and let's take a closer look at something:
Clear the error codes, maintain a steady pace, and observe the readings. The error message should not appear until the speed exceeds 20 km/h.
hg
Herbert.

Hello everyone, again...

Okay, I changed the wheel bearings in the spring/summer... so I can rule that out.
The distance from the ABS sensor is the same as on the right side.
The gears (ABS ring) also look good; I cleaned them with a wire brush, but they weren't excessively rusty.

When I start the engine and the vehicle is in motion, the turn signal on the front left side doesn't work. However, when the engine is off, the signal works perfectly.

It can occasionally happen that the ABS/ESP system temporarily malfunctions. However, I then experience the problem where the car, while in gear at low speed, suddenly surges forward with gas, then stops again (but I'm not yet in neutral).

What I also observed is that occasionally the speed reading is incorrect, showing a value that is too low, approximately half of the actual speed (e.g., displaying 25 km/h instead of 50 km/h).


I will take another, closer look at the ABS ring tomorrow, as well as the play of the half-shaft.

What happens if the speed sensor in the transmission is faulty? Can it trigger something like that?

Best regards,
Michi

First, check all ground connections and power supplies.

"If this doesn't work, try swapping the sensor wires for the front left (VL) and front right (VR) sensors at the control unit (STG) connection and see if the error moves from the left (Li) to the right (RE)."

Caution! Malfunction occurs during cornering!

It should also be possible to inspect it on a lift platform.
Is this TCU new or used?

First, check all ground connections and power supplies.

'If this doesn't work, try swapping the sensor wires for the front left (VL) and front right (VR) sensors at the control unit (STG) connection and see if the error moves from the left (Li) to the right (RE).'

Caution! Malfunction occurs during cornering!

It should also be possible to inspect it on a lift platform.
Is the engine control unit (ECU) new or used?

HI:::

Cross-swapping the control lines is not possible; the line at the control unit is simply too short ; I would have to run new lines.

I have already disconnected and reconnected the mass connectors (all the ones I know about) and then treated them with 'rope grease' for preservation.

Best regards,
Michi

The control unit was used.

The fact that the problem disappeared when the Lima device was removed suggests that it's related to the voltage.

It's unlikely to be a mechanical problem if it works with a lower voltage.
It definitely needs to be searched for in that direction.

Do you have access to an oscilloscope?

Quote:

What I also observed is that occasionally, the speed reading is also incorrect; it shows me a value that is too low, approximately half (instead of 50 km/h, it shows 25 km/h).

Please provide more specific information. Are you referring to the speed displayed on the speedometer, or data obtained through VCDS? If the latter, please specify the control module and the relevant measuring block. Please also provide translations for other measurements.
And again:

Quote:

Cross-connect the sensor wires for the left and right sides to the control unit supply line and see if the error from Li n: RE migrates

i.e., to the connector of the control unit.
hg
Herbert.