Technical Abs failure

[AbarthSA]

Hi Guys, i have a strange fault on my abarth...it has an abs failire message. I found that the wire at the left front wheel going to the brake pad was cut. I joined it and when i switch the ignition on the gault dissapeared...BUT as soon as i start the start the car it comes back again...what can cause that? It's bramd new pads as well.

And can such a fault habe an influence on the MAF sensor or circuit?

Thank you in advance

 

[bugsymike]

Hi Guys, i have a strange fault on my abarth...it has an abs failire message. I found that the wire at the left front wheel going to the brake pad was cut. I joined it and when i switch the ignition on the gault dissapeared...BUT as soon as i start the start the car it comes back again...what can cause that? It's bramd new pads as well.

And can such a fault habe an influence on the MAF sensor or circuit?

Thank you in advance

Generally I would have thought MAF issue separate.
Regarding ABS, are you sure it was a single wire and the one to the ABS sensor, as most are two, if two wires at the plug, often they can be tested with ignition light on and plug unplugged , careful not to short it, but look for battery voltage between the two terminals. Other than that a diagnostic tool that can read the movement at the individual abs sensors is useful as often with codes deleted engine started, but error comes back as you start to move off, which if the previous test was good would point to that sensor or the rotor/ magnet in the wheel bearing that triggers it.
If pads fitted recently by garage then tell them the ABS has stopped working since then, especially if a wire was cut.
By the way, not being rude, but are you sure the wire was not a wear indicator wire as some pads come without indicators.

 

[AbarthSA]

Generally I would have thought MAF issue separate.
Regarding ABS, are you sure it was a single wire and the one to the ABS sensor, as most are two, if two wires at the plug, often they can be tested with ignition light on and plug unplugged , careful not to short it, but look for battery voltage between the two terminals. Other than that a diagnostic tool that can read the movement at the individual abs sensors is useful as often with codes deleted engine started, but error comes back as you start to move off, which if the previous test was good would point to that sensor or the rotor/ magnet in the wheel bearing that triggers it.
If pads fitted recently by garage then tell them the ABS has stopped working since then, especially if a wire was cut.
By the way, not being rude, but are you sure the wire was not a wear indicator wire as some pads come without indicators.

My var had and abs/ebd failure before i changed the pads and showed even eith ignition on. Then i saw my pads were worn amd chanhed them. Its then when i saw the wire off...amd iys connected to the pad so must be a worn indicator. After i joined it is when this syarted happening. Will try and clear today while the engine is running and see what happens.

 

[bugsymike]

My var had and abs/ebd failure before i changed the pads and showed even eith ignition on. Then i saw my pads were worn amd chanhed them. Its then when i saw the wire off...amd iys connected to the pad so must be a worn indicator. After i joined it is when this syarted happening. Will try and clear today while the engine is running and see what happens.

Compare with the opposite side of the car, connections and readings with a meter.
Some form of diagnostic tool would be a help as the fault could be the opposite end of the car

 

[AbarthSA]

Compare with the opposite side of the car, connections and readings with a meter.
Some form of diagnostic tool would be a help as the fault could be the opposite end of the car

Wil do thanks a lot...i also noticed now that my cruise controll is not working as well....can it be related?

 

[bugsymike]

Wil do thanks a lot...i also noticed now that my cruise controll is not working as well....can it be related?

Very likely as it measures wheel speed.

 

[Ralf S.]

The wire to the pads is the brake wear indicator - nothing at all to do with the ABS. The wire is attached to a probe inside the pad. When the pad gets worn down to minimum, the probe earths through the brake disc and you get an alarm, which comes via the "handbrake" light, If the wire is cut, then obviously there will be no earth when the pads wear out, and no alarm.. but the car doesn't know whether the wire is cut or not. Not having it makes no difference to the brakes or the braking.. apart from you'll have no future warning that your pads are low.

The ABS sensor measures the wheel rotation at each corner. If one wheel is spinning at a different speed to the other one on the same axle. the car's brains think that wheel is locked, so the ABS comes on, to relieve brake force at that caliper.

The ABS sensors measure wheel rotation all the time, so the sensor is always feeding back a signal, If there is no signal when you start the car (the sensor is out of contact) then you get an ABS warning and ABS is disabled (brakes will work as non-ABS assisted brakes). If there is a sensor signal then that's cool.. but as soon as the wheels start to rotate, the ABS computer will be comparing the signals from each wheel. If one sensor is lazy or sending back poor information, or no information, then the ABS warning will come on and ABS will be disabled.

You have a sensor that is not communicating with the car. Replacing it is not too expensive and relatively easy, if the sensor bolt hasn't seized up or rounded off (it's an allen head, so they fill with water and just rust out the centre where the key goes).

Pardon our interruption...

Once you have the allen bolt out, you need to prise the sensor blade out of the caliper. Pull it out vertically.. it's like a little spade so if you bend it in the wrong direction, it will snap. The broken piece can be tapped out from inside the hub.. but use a plastic prong, pick or fork.. anything magnetic (steel screwdiver etc.) can de-mangnetise the tone ring.

The tone ring aka wheel speed sensor ring is a magnetized nitrile rubber ring, brown in colour.. on the back of the wheel bearing. It sends a magnetic spike to the sensor every time it passes from "north" to "south", so that the sensor knows how fast the wheel is going round.. by measuring how often it gets this signal. You don't want to ginger that ring up.


Ralf S.

 

[bugsymike]

With respect the member had the ABS issue prior to the brake pad issue, incidentally most modern pad wear indicators are a loop so the plug has two wires in effect, the idea when the pads wear down it breaks the connection. I believe earlier ones used a single wire but earthing through the disc proved unreliable.
A faulty "passive" ABS sensor may not show an error until the vehicle is moving, however an "active " or "Hall effect" sensor can through up an error code without moving , merely turning the ignition light on.
As I mentioned earlier the error code needs reading with a diagnostic tool as at present it could be at any wheel or anything in between that and the ABS Module etc.

 

[AbarthSA]

Thank you so much for the replies guys, i took her for a diagnostic test amd will post the results. Not quite sure what to think or what can be wrong....as well as the voltage while idling..really appreciate the help. I'm a newbie to Fiat but absolutely love my Abarth

 

[bugsymike]

According to the internet as below, which may be more to do with the ABS unit it's self rather than any ABS sensors, so maybe a garage job? What did your diagnostic guy say? Battery voltage seems strange also.?
A C1101 trouble code indicates that the vehicle's Engine Control Unit (ECU) has detected an unspecified failure in the Antilock Braking System's (ABS) hydraulic valve circuit.

 

[AbarthSA]

Thanks guys...can it be air im.the brake.fluid as.well..sorry for all the questions....appreciate.your help

 

[bugsymike]

Thanks guys...can it be air im.the brake.fluid as.well..sorry for all the questions....appreciate.your help

Unlikely, is the pedal spongy, are you losing brake fluid?
If you look on ABS pump issues here on the forum I notice around 2009 people were repairing ABS pump Modules with the same error code fitting new relays inside the pump housing.
However unless highly qualified I would not advise it!!!

 

[AbarthSA]

Unlikely, is the pedal spongy, are you losing brake fluid?
If you look on ABS pump issues here on the forum I notice around 2009 people were repairing ABS pump Modules with the same error code fitting new relays inside the pump housing.
However unless highly qualified I would not advise it!!!

Thank you bugsymike....really appreciaye your input. Regarding the errorcode on the MAF, do you think it's specific to tje sensor itself? Is there a way to comfirm it maybe, i'be read that the signs are bad idling ans stalling sometimes, black exhaust and heavy om fuel....here the part is quite expensive so don't wamt to.just spend....

 

[AbarthSA]

The wire to the pads is the brake wear indicator - nothing at all to do with the ABS. The wire is attached to a probe inside the pad. When the pad gets worn down to minimum, the probe earths through the brake disc and you get an alarm, which comes via the "handbrake" light, If the wire is cut, then obviously there will be no earth when the pads wear out, and no alarm.. but the car doesn't know whether the wire is cut or not. Not having it makes no difference to the brakes or the braking.. apart from you'll have no future warning that your pads are low.

The ABS sensor measures the wheel rotation at each corner. If one wheel is spinning at a different speed to the other one on the same axle. the car's brains think that wheel is locked, so the ABS comes on, to relieve brake force at that caliper.

The ABS sensors measure wheel rotation all the time, so the sensor is always feeding back a signal, If there is no signal when you start the car (the sensor is out of contact) then you get an ABS warning and ABS is disabled (brakes will work as non-ABS assisted brakes). If there is a sensor signal then that's cool.. but as soon as the wheels start to rotate, the ABS computer will be comparing the signals from each wheel. If one sensor is lazy or sending back poor information, or no information, then the ABS warning will come on and ABS will be disabled.

You have a sensor that is not communicating with the car. Replacing it is not too expensive and relatively easy, if the sensor bolt hasn't seized up or rounded off (it's an allen head, so they fill with water and just rust out the centre where the key goes).

Pardon our interruption...

Once you have the allen bolt out, you need to prise the sensor blade out of the caliper. Pull it out vertically.. it's like a little spade so if you bend it in the wrong direction, it will snap. The broken piece can be tapped out from inside the hub.. but use a plastic prong, pick or fork.. anything magnetic (steel screwdiver etc.) can de-mangnetise the tone ring.

The tone ring aka wheel speed sensor ring is a magnetized nitrile rubber ring, brown in colour.. on the back of the wheel bearing. It sends a magnetic spike to the sensor every time it passes from "north" to "south", so that the sensor knows how fast the wheel is going round.. by measuring how often it gets this signal. You don't want to ginger that ring up.


Ralf S.

Hi Ralf s, rhank you very much for the info...i'm exploring all.optioms at this stage. I took the car for a daignostic yesterday and posted the codes. How can i test them or do need to start changing one by one?

 

[bugsymike]

It sounds like you need a good automotive diagnostic specialist to pin point your problems, so you don't throw money in the wrong direction.
Re the MAF code, just fitting a sensor may not cure the problem, it can be wiring, the plug to the sensor, even the signal feed from the ECU .
On the battery code, what I meant was I was surprised it was raising it as an issue, I don't claim to be familiar with your model but generally car charging is between 13.8 and 14.2 volts so not terribly low at 13.41volts, are you having any battery issues, slow starting, dull headlamp beam, etc.
Having said that several people on the forum have error codes and stop / start function disabled etc. and they relate them to a battery problem cured by fitting the correct new battery recommended for their stop/start model. It's not something I have come across, but worth looking at.

 

[Ralf S.]

Hi Ralf s, rhank you very much for the info...i'm exploring all.optioms at this stage. I took the car for a daignostic yesterday and posted the codes. How can i test them or do need to start changing one by one?

The sensor wiring is about 18" long and connects to the car behind the wheel arch liners. I've not looked for the connectors for the rear sensors but the front ones are connected behind the headlamp, although you can only see them from inside the wheel arch, once you have removed the liners. Anyhow.. just follow the wire until you get to the connector.

It's a simple two-pin plug so the voltage coming out of the sensor should be measurable if you have very slender voltmeter probes and can find a way to spin the wheel. I'd expect any duff sensor to give a different voltage to the other 3 wheels but I don't know what values are good or bad.

If you only have a Mk1 analogue eyeball to work with, have a look for any visible damage or corrosion in the sensor... although I've never had a duff sensor that *looked* knackered.. they always looked okay but just didn't work.

The two front sensors are identical, as are the two rear sensors so depending on the cost of the parts compared to the cost of paying someone to investigate, it may be cheaper to put a new sensor on the front and see if that solves the problem.. otherwise put the sensor you removed on the offside. It's a bit hit and miss.. but £20 for a sensor, plus a bit of DIY vs £120 for a diagnosis and you still need to buy a sensor... it depends on how much the relative costs are in ZA.


Ralf S.