ABS and MSP remains lit (4200CC 2004)

[TKoos]

We just took our little black masterpiece some 5000 km to Modena and back, via Nordschleife.
Extremely fun trip that lasted two weeks.
Not as fun was the ABS/MSP lights that lit up just a few hundred km into Germany. :-/
The AC seized to work at the same time, but a "ventilation reset" fixed that problem. The ABS/MSP however is not going away.
From what I have understood from reading here and elsewhere this is likely to be due to a defect wheel sensor.
But how come the speedometer is working then? Someone somewhere said if it's an ABS sensor error it should be visible with OBD2 but neither of my two functioning readers gives any code for that.
I want to measure the sensors at the ABS box but fail to find a good picture where it's located.
Anyone who knows that, or have some other useful information?

 

[spkennyuk]

We just took our little black masterpiece some 5000 km to Modena and back, via Nordschleife.
Extremely fun trip that lasted two weeks.
Not as fun was the ABS/MSP lights that lit up just a few hundred km into Germany. :-/
The AC seized to work at the same time, but a "ventilation reset" fixed that problem. The ABS/MSP however is not going away.
From what I have understood from reading here and elsewhere this is likely to be due to a defect wheel sensor.
But how come the speedometer is working then? Someone somewhere said if it's an ABS sensor error it should be visible with OBD2 but neither of my two functioning readers gives any code for that.
I want to measure the sensors at the ABS box but fail to find a good picture where it's located.
Anyone who knows that, or have some other useful information?

View attachment 100621

The abs sensors use a hall effect sensor to independently check the speed at each wheel. Speedo on the dash is a different circuit.

If there is a small amount of wear at the wheel hub bearing then the sensor embeded into that hub will send an out of range signal to the abs ecu.

An intermitent fault will reset after restarting the car. A permanent fault will keep the light lit on the dashboard.

If an abs fault is showing your msp and hill hold will also not work.

You can read the code on a basic obd scanner on a 4200 onwards.

I think it depends on the age of the 3200 if you can read them or not with a basic obd

 

[TKoos]

Thanks for the reply!

We have a 4200 from year 2004.
There is no error code visible while reading with obd2, hence my question about where the box is located so I can measure the resistance of the sensors.

The abs sensors use a hall effect sensor to independently check the speed at each wheel. Speedo on the dash is a different circuit.

If there is a small amount of wear at the wheel hub bearing then the sensor embeded into that hub will send an out of range signal to the abs ecu.

An intermitent fault will reset after restarting the car. A permanent fault will keep the light lit on the dashboard.

If an abs fault is showing your msp and hill hold will also not work.

You can read the code on a basic obd scanner on a 4200 onwards.

I think it depends on the age of the 3200 if you can read them or not with a basic obd

 

[Zep]

If you cannot see the ABS module with your OBD2 reader, then you will not be able to read the speed sensor faults. If you can, it should be visible, but not all readers will see this module and will only show engine codes.

The speedo reading I believe is taken as an average of the sensors, which is why it still works when one is faulty.

 

[TKoos]

That my OBD2 readers cannot see the module would of course explain that. Both of them are cheap.

If you cannot see the ABS module with your OBD2 reader, then you will not be able to read the speed sensor faults. If you can, it should be visible, but not all readers will see this module and will only show engine codes.

The speedo reading I believe is taken as an average of the sensors, which is why it still works when one is faulty.

 

[TKoos]

I cannot seem to find the part number for the ABS sensor on scuderiacarparts. Anyone who knows where I should look?

 

[philw696]

I cannot seem to find the part number for the ABS sensor on scuderiacarparts. Anyone who knows where I should look?

It's part of the wheel bearing and hub assembly.

 

[TKoos]

This one?




Expensive little bugger. :-(
Any Alfa Romeo or Fiat parts to cheat with?

 

[philw696]

That's the one I'm afraid.

 

[allandwf]

I had this, on the Alfa, took an age to find as it ended up being a dodgy wheel bearing, just something else it may be.

 

[rs48635]

bad luck chap.
Keep the old bearing though. Mine was retained by garage who fixed ABS issue on my QP. I was told it is "mecahnics perk", which might be the case for low value items, cheeky cvnts!

 

[CatmanV2]

bad luck chap.
Keep the old bearing though. Mine was retained by garage who fixed ABS issue on my QP. I was told it is "mecahnics perk", which might be the case for low value items, cheeky cvnts!

Well it's not going to be much good to anyone.

C

 

[rs48635]

Well it's not going to be much good to anyone.

C

I would happily use it to replace a failed bearing, and live with an ABS light.
If was really no good , it would not have been kept! The better garages I have used return used parts

 

[CatmanV2]

I would happily use it to replace a failed bearing, and live with an ABS light.
If was really no good , it would not have been kept! The better garages I have used return used parts

Well I wouldn't argue that my good garages have always offered but I seldom take them. I don't know what the failure mode is, if the sensor goes because the bearing is failing?

C

 

[rs48635]

Well I wouldn't argue that my good garages have always offered but I seldom take them. I don't know what the failure mode is, if the sensor goes because the bearing is failing?

C

On my item the bearing was silent so any failing could not be detected. The posts above state that ABS is detecting different wheel speed, has this been confirmed? Maybe the sensor can have fault itself, where bearing is unaffected. I have been using old wheel bearing to mount brake disk for overhaul and painting. Also have vague plans to make kit car out of written-off QP where the upright and bearing would be useful without ABS.
Also having discarded on skyhook shock as "non-service item" it transpires they can be refurbished.

 

[Steve4200]

We just took our little black masterpiece some 5000 km to Modena and back, via Nordschleife.
Extremely fun trip that lasted two weeks.
Not as fun was the ABS/MSP lights that lit up just a few hundred km into Germany. :-/
The AC seized to work at the same time, but a "ventilation reset" fixed that problem. The ABS/MSP however is not going away.
From what I have understood from reading here and elsewhere this is likely to be due to a defect wheel sensor.
But how come the speedometer is working then? Someone somewhere said if it's an ABS sensor error it should be visible with OBD2 but neither of my two functioning readers gives any code for that.
I want to measure the sensors at the ABS box but fail to find a good picture where it's located.
Anyone who knows that, or have some other useful information?

View attachment 100621

The speedo should work on one ABS sensor. Normally the 4 sensors data is averaged within the bridge can which in turn sends pulses to the speedo on the 4200. You could try as a test by disconnecting the sensors then connecting a single sensor checking the speedo operation on each. Failing that diagnosis of the ABS module will be needed to show the fault.

Regards

 

[Neil robinson]

I have the exact same lights on. I replaced the f/o/s bearing and the fault came up. I hit a huge pothole with the rear n/s 50yds from the mechanics and I think the fault came on there, I just didn’t make the connection at the time. I’m trying the vertical acceleration sensor but have discovered the one I have is for m139 and I think mine is m138. I also cannot find it so it’s going to my mechanics for him to have a look. I’ve also bought a part from pccp in the hope that it works and is definately for my car. This has took me ages so far, and I’m no better off. If my mechanic can’t source or fix, then it’s off to main dealers for a diagnostic, no more blind buying!

 

[Neil robinson]

So, another hub replaced with the same lights staying on. On pressing the brake pedal to slow down(obv!) at the last second the brake pedal feels like it’s activating the abs with a type of fluttering coming through it. I think there is a thread somewhere on this problem but I cannot find it. Any help or knowledge will be greatly accepted. Neil

 

[philw696]

I wonder if you have an issue with the ABS pump or ECU do you have access to diagnostic gear or close to anyone with a Launch X431 ?

 

[Neil robinson]

Funny, one of the mechanics thought it might be an abs pump. I’ll see if my friend has a launch x431. Thanks very much, Neil