Emergency Brake Assist Failure

Emergency Brake Assist Failure

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Discussion

davek_964

Original Poster:

4,804 posts

107 months

Thursday 14th May 2015
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Bought my 2006 Vantage on Saturday, and up until this morning have been really impressed with it.

But while stopped at traffic lights this morning, I suddenly got a warning pop - Emergency Brake Assist Failure. Not great after only 5 days of ownership!

A quick search suggests it's relatively common, and is a sensor at the bottom of the brake master cylinder. One comment I found said it's a 10 minute change, although I can't find anything that says what's involved.

Anybody know? Given it's function, I assume that changing it would actually involve needing to bleed the brakes again afterwards.

Bouldermobile

66 posts

64 months

Thursday 14th May 2015
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Is it possible it could be the Pedal Travel Sensor rather than the Pressure Sensor? A friend of mine had a similar problem with his BMW and replacing this part cleared the problem.

If it were me I would change this first because a) it is slightly cheaper than the Pressure Sensor and b) probably doesn't involve bleeding the brakes, etc..

KnowsAnAston

20 posts

49 months

Monday 18th May 2015
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It won't be the brake light switch causing the issue. I'd get the pressure sensor in the master cylinder changed first, it's most likely to be the problem.

davek_964

Original Poster:

4,804 posts

107 months

Monday 18th May 2015
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KnowsAnAston said:
It won't be the brake light switch causing the issue. I'd get the pressure sensor in the master cylinder changed first, it's most likely to be the problem.
Yep, that's what I assumed - I've ordered one this morning. It's happened 4 or 5 times now, so I guess it will be obvious fairly quickly whether it's solved it.

Bouldermobile

66 posts

64 months

Monday 18th May 2015
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Just for clarification purposes: the 'Pedal Travel sensor' is a roughly cylindrical shaped part attached to the brake servo (located under the bonnet) as opposed to the 'Brake Stop Light switch', which is located in the car and attached to the pedal box assembly. However, I do concur with Dave that it won't be the Brake Stop Light Switch.

Not sure if the Pedal Travel Sensor and the Pressure Transducer both work with the Emergency Brake Assist system so do let us know how you get on!
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davek_964

Original Poster:

4,804 posts

107 months

Monday 18th May 2015
quotequote all
Bouldermobile said:
Just for clarification purposes: the 'Pedal Travel sensor' is a roughly cylindrical shaped part attached to the brake servo (located under the bonnet) as opposed to the 'Brake Stop Light switch', which is located in the car and attached to the pedal box assembly. However, I do concur with Dave that it won't be the Brake Stop Light Switch.

Not sure if the Pedal Travel Sensor and the Pressure Transducer both work with the Emergency Brake Assist system so do let us know how you get on!
Are we talking about the same thing? The transducer is also cylindrical and is attached to the bottom of the master cylinder. Item 4 in the diagram here :

http://astonmartinbits.com/models/5-V8-Vantage/par...

That's what I've ordered anyway!

Bouldermobile

66 posts

64 months

Monday 18th May 2015
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Yes, the Pressure Transducer is number 4 on the parts diagram given on that webpage, and the Pedal Travel sensor is number 13 on the same diagram.

Hope that helps; good luck!

davek_964

Original Poster:

4,804 posts

107 months

Monday 18th May 2015
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Cool - if number 4 doesn't solve it, I'll try number 13!

davek_964

Original Poster:

4,804 posts

107 months

Monday 29th June 2015
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On Thursday, the failure came up again - both times I used the car (morning / evening). It hadn't shown for about a month, so I hadn't fitted the new sensor yet.

I changed the sensor Thursday evening and that seemed to cure the problem - until this morning. The failure has shown up again, so I guess it's not the sensor.

So, it might be the pedal travel sensor after all. Will need to investigate further.

huggy1

105 posts

91 months

Tuesday 30th June 2015
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Mine did the same last year. I have the RAC parts and labour warranty (costs about £80 for £750 worth of cover per fault). Got recovered to the dealer and they changer both front ABS sensors. They are only about £30 each and look simple enough to change but it's diagnosing that's the trick on this one.

davek_964

Original Poster:

4,804 posts

107 months

Tuesday 30th June 2015
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huggy1 said:
Mine did the same last year. I have the RAC parts and labour warranty (costs about £80 for £750 worth of cover per fault). Got recovered to the dealer and they changer both front ABS sensors. They are only about £30 each and look simple enough to change but it's diagnosing that's the trick on this one.
Did that give you EBA failure but nothing else? I assumed I'd get ABS / traction failures as well if it was an ABS sensor.
I suspect I may have to take it to a dealer to get them to have a look - hopefully their diagnostics will give more info.

wafu1983

27 posts

64 months

Tuesday 30th June 2015
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davek_964 said:
On Thursday, the failure came up again - both times I used the car (morning / evening). It hadn't shown for about a month, so I hadn't fitted the new sensor yet.

I changed the sensor Thursday evening and that seemed to cure the problem - until this morning. The failure has shown up again, so I guess it's not the sensor.

So, it might be the pedal travel sensor after all. Will need to investigate further.
Can you elaborate a little on how you fitted the sensor? I have just ordered a Brake Pressure Transducer too, although in my case I am looking to fix a 'DSC Service Required' message. The sensor is easy enough to access, but I am concerned that needing to bleed the brakes afterwards might be beyond my abilities. Also I wondered if changing the component would also necessitate some kind of diagnostic system input?

davek_964

Original Poster:

4,804 posts

107 months

Tuesday 30th June 2015
quotequote all
wafu1983 said:
Can you elaborate a little on how you fitted the sensor? I have just ordered a Brake Pressure Transducer too, although in my case I am looking to fix a 'DSC Service Required' message. The sensor is easy enough to access, but I am concerned that needing to bleed the brakes afterwards might be beyond my abilities. Also I wondered if changing the component would also necessitate some kind of diagnostic system input?
I was worried I may have to bleed too, but found threads saying it was a 10 min job so figured that couldn't include bleeding.

First warning - the sensor part means you cannot get a normal socket on it - the sensor connector is too deep unless you have a deep socket of that size (which I didn't). I tried an adjustable spanner which was too long for any movement and I nearly gave up - then remembered I had a small toolkit I keep in the car and that had a shorter adjustable spanner in it.

I lost very little fluid when removing the old sensor - in fact I'd say the only fluid that came out was what was in the sensor itself.

I filled the new sensor with fluid so that I wasn't introducing air, then just tightened it up.

My fault is intermittent so I had nothing to clear.

wafu1983

27 posts

64 months

Tuesday 30th June 2015
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Thanks Dave, most helpful!

I have a cracking set of ratchet spanners that should be just the job. I'll let you know how I get on!

With these feet

5,406 posts

147 months

Wednesday 1st July 2015
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Have you had the fault codes read with AMDS? It is quite specific as to which sensor is at fault, if it is one.

Had a Vantage in a while ago with emergency brake failure lights on, checked through all the easiest options but ended up being the ABS unit itself that was at fault. Unfortunately not a cheap job, £800 ish in parts and about an hour to change.

davek_964

Original Poster:

4,804 posts

107 months

Wednesday 1st July 2015
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With these feet said:
Have you had the fault codes read with AMDS? It is quite specific as to which sensor is at fault, if it is one.

Had a Vantage in a while ago with emergency brake failure lights on, checked through all the easiest options but ended up being the ABS unit itself that was at fault. Unfortunately not a cheap job, £800 ish in parts and about an hour to change.
I'll hope it's not that then!

My fault comes and goes - I assume they would need to read the codes while I actually have the fault showing? That would be difficult unless it gets much worse than it is now.

leerandle

496 posts

39 months

Wednesday 1st July 2015
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I occasionally get the DSC disabled light flick on the dash when starting up. I went to the AM dealers in Cheltenham and they diagnosed a Brake Pedal Travel Sensor and Brake Pressure Transducer that needs replacing. I am told it is usually just the Brake Pressure Transducer that fails. They are due to be delivered over the next fews days, so I will let you know how I get on swapping them over. I am hoping they are just multiplug style connectors so no need to bleed brakes and should be 'easy' access as they both attach to the Master Brake Cylinder.

I have added a link below that shows you the parts diagram:

http://astonmartinbits.com/models/5-V8-Vantage/par...

No. 4 = Brake Pressure Transdcuer
No. 13 = Brake Pedal Travel Sensor


Regards,

Lee



davek_964

Original Poster:

4,804 posts

107 months

Wednesday 1st July 2015
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The brake pressure transducer is simple, but see my previous post about spanner size.

I'd be interested in how you get on with the pedal travel sensor. As far as I can see, it has a vaccuum pipe attached to it, so it is more than just a simple electrical connector. I've not looked at how easy it would be to replace though.


leerandle

496 posts

39 months

Thursday 2nd July 2015
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davek, I'll do some digging and find out the correct procedure for replacement. Althought its an AM, I'm assuming the braking system is principly the same as all other cars. I'll see what I can find out and post on here.

davek_964

Original Poster:

4,804 posts

107 months

Thursday 2nd July 2015
quotequote all
Mine came on again this morning when I started the car. Interestingly, taking the key out doesn't seem to clear the code but locking / unlocking does.

I am debating whether to give the pedal travel sensor a try or just accept defeat and take it to a specialist to see if they can figure it out.