Hi guys,

Wondering what the different ways are that abs can fail? Have searched the forum but even just putting 'abs' or 'antilock' I get nothing.

As said in subject line, car details: 6N2 1.4 8v Petrol, Drums on rear, 129,000 miles. Rear brake shoes and cylinders still original. Brake fluid not been changed (and since overlooked) for many a year follow a ceased nipple on the front rhs. Boiling point of fluid still reads within limits at garage though.

All through the life of the car I've had times when the abs light would come on or not go out after starting the car but it's never lasted long enough to be a problem or affect an MOT. And it could often be six months to a year before it happened again. Couldn't work that out and thought it might be dirt in the reluctor/abs rings or something.

CURRENT PROBLEM: ABS light is on often. When it does go out I end up driving a few miles before I feel the ABS kick in under my foot whilst braking. The difference is, I'm not braking hard enough for the ABS to kick at the times it would normally. After I feel the ABS kick in - the warning light comes back on shortly afterwards.

Also - I can see the rings on the front hub whilst under the car but have no idea how rings or sensors work on a rear drum. Can anyone explain? Google is being very helpful for me.

Thanks in advance,

Simon

I'd start by getting it scanned for any fault codes, that way your not going to replace items in the hope of a fix :)

The sensor ring fits over the stub axle on the rear drum #11 in this picture

Thanks for the reply and pointing me to the sensor ring on the rear drum. I'm gonna try and get the codes scanned and the car checked over early next week.

Edit: I don't know how you explain the difference but I have the drums with a bearing integrated in the drum. The cotter pin, the castelated nut and all that. Is that setup much different?

Edited 9 December, 201510 yr by cosaw

They changed to your type of bearing - the adjustable ones are only on older models.

As Nige says, get the codes read - It is probably nothing more than a dodgy sensor or even connection - the question that reading the codes will answer, is 'which one'.

Regards

Your 6N2 should have the setup I put up before, The 6N1 had the bearing in drum setup as shown in this pic below, the ABS ring is #19

Thanks for the extra picture. Bit weird though. Not saying Haynes is correct but it shows the second setup and am pretty sure that's the setup I've got also but will check.

As a matter of interest - what are the advantages of each setup with regard to usage and service?

As said hope to get it in the garage next week.

The setup that should be on your 6N2 (first pic) means you can remove the drums to service the shoes without disturbing the bearings, so making it an easier job, the only downside is if the bearings fail, you have to replace the whole assembly #20 in first pic, where as on the earlier setup you could just replace the bearings in the drum.

Ok. Halfords did a scan for me. Report says, ABS Sensor: O/S/F ABS Sensor faulty advise cleaning abs pickup. £132.66

There was a whole list of other stuff too which point to why I should get a new vehicle but let's concentrate on this. Sounds to me like until they fit it the don't know if it's gonna cure the fault.

Is this a relatively easy job to do myself?

I wouldn't trust Halfords to put a sticker on a pushbike !!

Did they give you the actual code and the real world meaning? as there are 3 real world meaning defects If it is the sensor then it's held into the hub unit by a single bolt then it should pull out, I would have a close look at the wiring coming from the sensor as they are known to break over time

I would agree with Nige my mate had a similar problem on his laguna it turned out to be damaged wiring in the front wheel arch

No they didn't give me a fault code. The local Halfords Autocenter I go to has mostly been pretty good when it comes to helping me out with my car. But I'm sure others have had different experience.

If I can get to the wiring then I can check it. I'm pretty good with electronics and a multimeter so can do continuity testing fix the odd amplifier and all that sort of stuff. I just don't have the tools or the practice to do modern cars in general - I'm in too much trouble if I stuff up. However if I can get to both ends of the cable with my multimeter then it shouldn't be a problem. I should be able to take a resistance measurement across the sensor too if I can reach it.

Is putting it on ramps the route - if I don't have to take a wheel off then ramps are preferable.

Here's a link to the wiring diagrams http://s1117.photobucket.com/user/nige8021/library/Wiring%20Diagrams%202/6N2%20ABS

Thanks Nige - that's awesome! I will take a look.

Generally on the 6n2 system, it's a dirty connection. Mainly it's in the main connector to the pump unit itself. This is relatively easy to get at, it's just behind the battery. It has a slider lock on it, so use a screwdriver in the slot and pull it up slowly. Then pull the plug off, you will no doubt find a nice green residue inside. A bit of wd40 etc inside should solve this.

As for the wheel sensor, it's much the same. They are behind the hub and very easy to get at with the wheels off.

If you have both the main plug off and the wheel sensor plug off, then using the above wiring diagram you can check continuity between each end.

The front sensor are relatively cheap on eBay, the rears are specific to this car so are a little more. I wouldn't go changing them without checking every other possibility first though as it actually makes it more complicated.

Also a possible cause for this is excessive rust on the ring itself, you can get at this fairly easily if you take the brake disc off, then give the outer side (the side it reads) a good going over with a wire brush.

Wow Dixy that's great info. Many thanks. Will have a look at the car as soon as I can.

Ok. Got the connector on the ABS pump and think I've found a picture of how to undo it - never would have guessed otherwise. Do I need to disconnect the battery first and and are there any other precautions?