ABS Light on After New Gear Box

iain1976 · 16-01-2008, 15:32

Hi guys,

I've just had my Octavia back from the garage after getting a new gear box and clutch fitted. One of the first things that the mechanic said was "Do you know that you've got a problem with your ABS pump"? Now, before I went in I had never noticed any problems braking, and my wife drives the car every day for a fair distance and never reported any issues either.

However, when I drove away from the forecourt the ABS light was on on the dashboard. I phoned the garage and explained to them that this was NOT on prior to me putting the car in to get work done and they've said that they will "Take a look" but claim that nothing to do with the ABS could have been messed with during the fitting of the gear box and clutch.

Do any of you have any experience with anything like this? Any help would be gratefully received as I am not mechnically minded at all!

Many thanks in advance!

Iain

Tom_vRS · 16-01-2008, 15:53

Could be one of a many of things. You really need a diagnostics check running, does someone have VAGCOM near you??

They will have disturbed the driveshafts, but short of damaging an ABS sensor they wouldn't of touched anything ABS related...

iain1976 · 16-01-2008, 16:43

Sadly I'm not near one of those, but the garage are presumably going to check it out (they said that they would do so for free).

The scary thing is that the ABS pump has really started pumping when you brake, so much so that I've removed the fuse to disable it (as it feels very wrong). Is this stupid and daft?

I would be willing to swear on my life that this wasn't happening before I put the car in so if anyone could give me any pointers as to what could possibly have gone wrong that would be great!

Could a damaged sensor make the pump behave like this?

Iain

iain1976 · 16-01-2008, 17:47

Hmm... I've just read that the sensors for the ABS regulate how the pump works. Would damage to one of them cause this sort of behaviour?

mathepac · 16-01-2008, 17:50

Dunno about the Octy, but Fabias have a common brake / clutch reservoir so if you mess with the clutch hydraulics on a Fabia, you may have to bleed the brakes and vice versa.

Might be a red herring.

andy01taxi · 16-01-2008, 18:16

i had the same prob it was the sensor on the hub carrier that was bent

andy01taxi · 16-01-2008, 18:18

could also be dirt on the sensor clean whith a dry paint brush

iain1976 · 16-01-2008, 18:38

Cool - are their any diagrams/photos anywhere showing where that is? Does it involve taking the cover at the bottom off?

fordfan · 16-01-2008, 20:07

I always thought that when the ABS light was on, you lost the anti-lock functionality of the brakes - with this the pedal would not pulse. The ABS sensors regulate nothing - they communicate to the control unit the wheel speeds and it is the control unit that tells the hydraulics what to do. I can't see them really going near the sensors as they will unbolt the driveshafts at the flanges on the gearbox, if they did remove a driveshaft it is very likely to have been the left one.

I am inclined to think that it could be a terminal 30 fault - there is an electrical connection between the air filter housing and the battery, as I suspect that they may have had to remove the battery and/or air filter this plug could have been dislodged.

The clutch fluid take off on the brake master cylinder reservoir is high enough so as not to allow air into the brake hydraulics.

Edit - don't forget to replace the fuse when they check it.

iain1976 · 16-01-2008, 20:41

Thanks for the tips. I'll post tomorrow and let you know how I get on.

KenONeill · 17-01-2008, 12:36

They shouldn't have needed to touch anything other than the wheel sensors (and damage there will indeed turn the ABS off). However, I'm not sure what might be strained if the engine tail wasn't properly supported whilst the box was out of the car.

iain1976 · 17-01-2008, 20:25

Well, good news! Seems that all that was wrong was that one of the driveshafts (I *think* that's what he said; I was too busy exhaling in relief at the time) was slightly out of alignment which was causing the problem. They sorted it there and then for no charge and now it's peachy again!

As a big plus to the garage, the customer service was absolutely excellent. No quibbling or anything. They simply took a look and sorted things.

Many thanks to all of you who took the time to read this and offer advice!

16-01-2008, 15:32	#1
iain1976 Briskodian Join Date: Sep 2007 Posts: 18 Thanks: 2 Thanked 1 Time in 1 Post	ABS Light on After New Gear Box Hi guys, I've just had my Octavia back from the garage after getting a new gear box and clutch fitted. One of the first things that the mechanic said was "Do you know that you've got a problem with your ABS pump"? Now, before I went in I had never noticed any problems braking, and my wife drives the car every day for a fair distance and never reported any issues either. However, when I drove away from the forecourt the ABS light was on on the dashboard. I phoned the garage and explained to them that this was NOT on prior to me putting the car in to get work done and they've said that they will "Take a look" but claim that nothing to do with the ABS could have been messed with during the fitting of the gear box and clutch. Do any of you have any experience with anything like this? Any help would be gratefully received as I am not mechnically minded at all! Many thanks in advance! Iain

16-01-2008, 15:53	#2
Tom_vRS Briskodaholic Join Date: Dec 2004 Location: Fenland, Cambridgeshire Posts: 10,716 Thanks: 556 Thanked 361 Times in 243 Posts	Re: ABS Light on After New Gear Box Could be one of a many of things. You really need a diagnostics check running, does someone have VAGCOM near you?? They will have disturbed the driveshafts, but short of damaging an ABS sensor they wouldn't of touched anything ABS related... __________________ 97/R BMW 328i in Boston Green. << Clickable for boring info. My Journal

16-01-2008, 16:43	#3
iain1976 Briskodian Join Date: Sep 2007 Posts: 18 Thanks: 2 Thanked 1 Time in 1 Post	Re: ABS Light on After New Gear Box Sadly I'm not near one of those, but the garage are presumably going to check it out (they said that they would do so for free). The scary thing is that the ABS pump has really started pumping when you brake, so much so that I've removed the fuse to disable it (as it feels very wrong). Is this stupid and daft? I would be willing to swear on my life that this wasn't happening before I put the car in so if anyone could give me any pointers as to what could possibly have gone wrong that would be great! Could a damaged sensor make the pump behave like this? Iain

16-01-2008, 17:47	#4
iain1976 Briskodian Join Date: Sep 2007 Posts: 18 Thanks: 2 Thanked 1 Time in 1 Post	Re: ABS Light on After New Gear Box Hmm... I've just read that the sensors for the ABS regulate how the pump works. Would damage to one of them cause this sort of behaviour?

16-01-2008, 17:50	#5
mathepac Briskodian Join Date: Oct 2007 Location: Kilkenny, Ireland Posts: 1,005 Thanks: 30 Thanked 53 Times in 51 Posts	Re: ABS Light on After New Gear Box Dunno about the Octy, but Fabias have a common brake / clutch reservoir so if you mess with the clutch hydraulics on a Fabia, you may have to bleed the brakes and vice versa. Might be a red herring.

16-01-2008, 18:16	#6
andy01taxi Briskodian Join Date: Nov 2007 Posts: 9 Thanks: 4 Thanked 0 Times in 0 Posts	Re: ABS Light on After New Gear Box i had the same prob it was the sensor on the hub carrier that was bent

16-01-2008, 18:18	#7
andy01taxi Briskodian Join Date: Nov 2007 Posts: 9 Thanks: 4 Thanked 0 Times in 0 Posts	Re: ABS Light on After New Gear Box could also be dirt on the sensor clean whith a dry paint brush

16-01-2008, 18:38	#8
iain1976 Briskodian Join Date: Sep 2007 Posts: 18 Thanks: 2 Thanked 1 Time in 1 Post	Re: ABS Light on After New Gear Box Cool - are their any diagrams/photos anywhere showing where that is? Does it involve taking the cover at the bottom off?

16-01-2008, 20:07	#9
fordfan ECUless Join Date: Mar 2005 Posts: 1,823 Thanks: 28 Thanked 202 Times in 176 Posts	Re: ABS Light on After New Gear Box I always thought that when the ABS light was on, you lost the anti-lock functionality of the brakes - with this the pedal would not pulse. The ABS sensors regulate nothing - they communicate to the control unit the wheel speeds and it is the control unit that tells the hydraulics what to do. I can't see them really going near the sensors as they will unbolt the driveshafts at the flanges on the gearbox, if they did remove a driveshaft it is very likely to have been the left one. I am inclined to think that it could be a terminal 30 fault - there is an electrical connection between the air filter housing and the battery, as I suspect that they may have had to remove the battery and/or air filter this plug could have been dislodged. The clutch fluid take off on the brake master cylinder reservoir is high enough so as not to allow air into the brake hydraulics. Edit - don't forget to replace the fuse when they check it. Last edited by fordfan; 16-01-2008 at 20:12.

16-01-2008, 20:41	#10
iain1976 Briskodian Join Date: Sep 2007 Posts: 18 Thanks: 2 Thanked 1 Time in 1 Post	Re: ABS Light on After New Gear Box Thanks for the tips. I'll post tomorrow and let you know how I get on.

17-01-2008, 12:36	#11
KenONeill Briskodian Join Date: May 2006 Location: Normally somewhere in Scotland! Posts: 9,326 Thanks: 43 Thanked 434 Times in 427 Posts	Re: ABS Light on After New Gear Box They shouldn't have needed to touch anything other than the wheel sensors (and damage there will indeed turn the ABS off). However, I'm not sure what might be strained if the engine tail wasn't properly supported whilst the box was out of the car.

17-01-2008, 20:25	#12
iain1976 Briskodian Join Date: Sep 2007 Posts: 18 Thanks: 2 Thanked 1 Time in 1 Post	Re: ABS Light on After New Gear Box Well, good news! Seems that all that was wrong was that one of the driveshafts (I think that's what he said; I was too busy exhaling in relief at the time) was slightly out of alignment which was causing the problem. They sorted it there and then for no charge and now it's peachy again! As a big plus to the garage, the customer service was absolutely excellent. No quibbling or anything. They simply took a look and sorted things. Many thanks to all of you who took the time to read this and offer advice!

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