[AlfaNoMore]

I know this is a common fault with Alfa but has anyone got any tips for my specific problem?

The warning only ever seems to come up during very slow braking for instance when I am stop/start in slow traffic.

The car had the brake switch replaced last year before I bought it. I have had the problem for a while now intermitantly but it seems to be doing it more regularly these days.

My local garage (not Alfa dealer) has had a quick look and there are no faults recorded. The only thing he could find was that the ABS ECU (I think) was showing that the car was doing 1mph when it was actually stationary.

I am getting rid of the car soon and want to try and sort it enough so I can sell it.

Any ideas?

 

[Dave Brand]

Even though the brake light switch has been replaced it does have all the symptoms of a faulty one! For what they cost it may be worth replacing the brake light switch. You could try taking it off & giving it a good dousing in contact cleaner - that "cured" mine for a few days!

 

[AlfaNoMore]

Even though the brake light switch has been replaced it does have all the symptoms of a faulty one! For what they cost it may be worth replacing the brake light switch. You could try taking it off & giving it a good dousing in contact cleaner - that "cured" mine for a few days!

Sounds like a plan, hopefully it is just something loose/dirty on the switch!

 

[AlfaNoMore]

Tried cleaning the switch but that hasn't helped.

Is there a way I can test the switch to see if it faulty?

 

[Sharpshooter]

You should be able to use a Multimeter on Resistance mode. When the switch is not pressed you should have an open circuit, ie no reading. When pressed you should hopefully get a reading of zero.

 

[Sharpshooter]

On another note. It sounds to me like you have swarf stuck to the end of one of your ABS sensors. This could give the reading you show. Try jacking up the vehicle (using an axle stand) and using a small brush like a paintbrush, dust off the ends of the sensors. After a while they become slightly magnetic, and any rust or metallic dust in the area can stick to them. This same thing happened to my friend on his Audi.

Hope it helps.

 

[AlfaNoMore]

On another note. It sounds to me like you have swarf stuck to the end of one of your ABS sensors. This could give the reading you show. Try jacking up the vehicle (using an axle stand) and using a small brush like a paintbrush, dust off the ends of the sensors. After a while they become slightly magnetic, and any rust or metallic dust in the area can stick to them. This same thing happened to my friend on his Audi.

Hope it helps.

Are the sensors easy to identify?

I assume the wheels will have to come off to find them?

 

[bobda]

I'd say battery. I had the same issue a few weeks ago. The low speed and stop/start traffic means that the Sele pump is being used more so drawing more power. The CANBUS system that operates the ABS/VDC is sensitive to voltage fluctuations.
Get one specified for a 147 JTD.

 

[FoxtrotOscar]

Perhaps connecting to a diagnostic machine might eliminate some of the guesswork? Does sound very much like brake switch problem, though. The switches are very poor quality; I once had to fit 3 brand new ones before finding one that worked prpoerly...

 

[AlfaNoMore]

Perhaps connecting to a diagnostic machine might eliminate some of the guesswork? Does sound very much like brake switch problem, though. The switches are very poor quality; I once had to fit 3 brand new ones before finding one that worked prpoerly...

Last time it was connected to a diagnostic machine it didn't report any fault codes.

 

[Dave Brand]

Last time it was connected to a diagnostic machine it didn't report any fault codes.

A faulty brake light switch doesn't set any fault codes.

 

[Alexie]

A faulty brake light switch doesn't set any fault codes.

I'm not sure that's necessarily correct. I had a fault with the electrical supply to the switch the other day caused by a blown fuse. This caused ABS/VDC failure but only when the pedal wasn't pressed. If the pedal was pressed when you started the car there was no ABS failure until you released the pedal. The diagnostics clearly said Brake Switch Fault (using FiatECUScan). As I say, it turned out to be a blown fuse, nothing wrong with the switch.

http://www.alfaowner.com/Forum/alfa-147-156-and-gt/113298-147-climate-control-problem.html

 

[FoxtrotOscar]

OK, so what is the EXACT warning message that you get?
Have you checked the multiplug on the ABS ecu (susceptible to water ingress/corrosion)?

 

[AlfaNoMore]

OK, so what is the EXACT warning message that you get?
Have you checked the multiplug on the ABS ecu (susceptible to water ingress/corrosion)?

Haven't driven the car over the weekend but I will make a note of the exact message next time it happens.

Where is the ABS ecu, is the the one behind the battery?

 

[AlfaNoMore]

Haven't driven the car over the weekend but I will make a note of the exact message next time it happens.

Where is the ABS ecu, is the the one behind the battery?

The exact message I get is ABS System Failure and then about 10 seconds later it swaps to VDC system failure. After about 15 to 20 seconds the message then disapear and it just shows the warning light by the rev counter.

 

[Dave Brand]

The exact message I get is ABS System Failure and then about 10 seconds later it swaps to VDC system failure. After about 15 to 20 seconds the message then disapear and it just shows the warning light by the rev counter.

That was the sequence I was getting with a faulty brake light switch.

 

[FoxtrotOscar]

If you are seeing those messages, I would definitely expect there to be error codes stored in the ECU; I would suggest you get it read again.

 

[bobda]

If you are seeing those messages, I would definitely expect there to be error codes stored in the ECU; I would suggest you get it read again.

It's likely that the 'non-alfa' garage that scanned it for fault codes was just scanning the engine ECU though. ABS/VDC faults are stored in the ABS ECU.
Alfadiag, for example doesn't connect to the ABS ECU in a 147.
FIAT ECU scanner (which is free) will, though; Fiat ECU Scanner - Fiat/Alfa/Lancia ECU Reader

 

[Dave Brand]

ABS/VDC faults are stored in the ABS ECU.
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See post #11 in this thread!

I had similar problems caused by a faulty brake light switch; neither Bosch diagnostics nor Alfa Examiner found any fault codes.

 

[Alexie]

There are 2 sets of contacts on the brake switch which work opposite to each other, i.e. when 1 is open the other is closed and visa versa. When I had fuse F35 blow, due to a reversing light problem, I got ABS/VDC failure. This is because fuse F35 feeds the brake pedal NOT pressed switch contact which normally sends a +ve signal from the brake switch to the ABS control unit with the pedal NOT pressed (to inhibit ABS when there is no braking). The ABS control unit also gets a signal from the other switch contact on the brake switch which tells it the brake pedal is pressed. This is why I was getting ABS/VDC failure, the ABS control unit knew the pedal wasn't pressed, from one contact, but wasn't getting a signal to say the brake pedal was not pressed (due to blown fuse) from the other contact so it threw a wobbler and a failure. I got a Brake Pedal Switch failure in FiatECUScaner for this fault. I'm guessing that if the switch fails in some other way you won't get a fault code ... in which case why does the ABS control unit throw a fault ? Sounds like a bug to me. As I said elsewhere, if I started the car with the brake pedal depressed I got no failure. I only got the failure the instant I released the brake pedal and the ABS control unit realised that one of the switch contacts wasn't working.

The brake switch probably causes problems because any slight mismatch between 1 contact opening and the other closing will throw an ABS error. All in all, not the most intelligent bit of design since you loose ABS all for the sake of a blown fuse that protects only non safety critical functions (reversing light, cruise control, climate control light !). Luckily it doesn't affect the EBD.