I suspect that the abs sensor gap is not correct. Make sure the sensor is seated properly and you will have to look inside for bits attached to the sensor

 

can someone post an exploded view of the peugeot 407 front hub, i cant get my head round where the ABS teeth are, do i need to clean down the ABS hole, or down and side ways towards the brake disk ?

thanks

 

They are inside the wheel bearing. You won't be able to see them.

 

wot no teeth

so does this mean, i probably havnt got anything stuck in the teeth because there arnt any teeth exposed ?

 

Hi,
You won't have anything stuck in the teeth as there are none, the magnetic ring is smooth.

I know nothing about the set up on the 407, but if the magnetic sender is in the wheel bearing it must be a very similar set up to that of the Renault Laguna mk2 which I do know a bit about.

I've just had a look at a picture of the bearing for a 407 and it looks identical to the type used on the Laguna, so I'll tell you what I know.

The magnetic ring is part of the bearing, it is a quite delicate item and easily damaged. It has a certain amount of magnetic segments in it, as these pass by the ABS sensor they create the magnetic field that the sensor can recognise. If any of these segments are damaged the magnetic pulses to the sensor will be incorrect and the ABS system will flag a fault.

On the Laguna the Left front (NSF) ABS sensor (speed sensor) also supplies the pulses for the speedometer it may be the same on the 407?
Strangely enough the speedo will continue to work even though the ABS system is seeing a fault, this is because the ABS system needs a lot more pulses than the speedo does.

Can you read live data with Peugeot planet?
if you can, you will probably find that the pulses from the NSF speed sensor are irregular.
Assuming that there are no wiring faults the fault is probably the bearing.

As the magnetic ring is part of the bearing the bearing needs to be changed to renew it, this has to be done very carefully, no hammering the bearing in, it needs to be pressed in very very carefully, I can't stress enough how fragile and easily damaged these magnetic rings are!


Cheers.


PS.
To answer a question from your other post (peugeot 407 ABS problem ) if the ABS sensor is the 2 wire type you cant get a reliable resistance reading from them, they need to have power to them to enable you to do this.

 

Thankyou

It may be that i damaged the bearing when i drilled out the old sensor.
Ive looked down the hole while i rotate the brake disk, and i cant see any damage.

I didnt do any hammering so i am still hoping looking for old sensor detritus tomorrow in the light will get me out of this fix.

thanks for your reply, i think your Laguna experience is very applicable

 

But you had the fault before you drilled out the sensor !
(Sorry, just re read your 1st post and seen that the fault changed)

I've just looked and I think you can read live data wit peugeot planet so have a look and see if you can do it.
I'm not sure what it will be able to do but maybe you can see some sort of graph representation of the ABS sensor output, maybe then you can see if the pulses are irregular.

Well actually they must be irregular or you wouldn't have a fault would you

So, you know it's not the sensor as you have fitted a new one, assuming the new one is ok.

If I were you I would go to the wiring next, you need to check that the wiring from the wheel arch plug that the ABS sensor plugs into is ok up to the ABS module plug.

This will entail disconnecting the big plug from the ABS pump and finding the correct pins that connect to the plug in the wheel arch. A continuity test on the wiring will show if the wiring is ok.

If the wiring is ok then all that is left is the bearing magnetic ring, or the ABS pump itself has developed a fault. This happens on the Lagunas, the pump just stops working.


What year is your car?
What engine and power?


Cheers.

 

Well here is the lastest update.

to recap i'm having probs with the left hand front abs sensor, when lookinf at the PP2000 dynamic speed, ever once in a while the ourput dips to half its proper value, I cant seem to predict when it going to happen - it odesnt happen every 3 secs or anything like that.

I had a another look at the left hub, and found the tip of the old ABS sensor that i had to drill out, rolling around between the driveshaft and the hub, i hoped removing this would fix the situation, but it made no difference.
------------------------

I made an extension lead so I could wire the right hand sensor into the left hand input of the ABS.

When i did this the read out on PP2000 was fine for the left !

I think this test has eliminated the ABS ECU (good news) and the wiring between the ABS plug under the engine fusebox and the ABS ECU being faulty
-------------------
Just to check I didnt have 2 dodgy abs pickups i swapped the right front with the left front, and the fault stayed with the left front wheel.

conclusion its not the abs sensor
-------------------
With the tow front wheels jacked up I was able to put the car in reverse and work carefully on the abs sensor with the hub being turned by the engine.

I removed the abs sensor securing bolt, no amount of adjusting or tuning or pressure on the ABS sensor would make the fault go away.

----------------------
Using my "abs extension lead", i was also able to look at the signal with an oscilloscope.

I was expecting to see a weak signal on the one side, but in fact the signal was quite a nice square one, - but every once in a while there are missing "teeth".

 

Wheel bearing starting to fail???
As these are what the abs sensor get readings from.

Total guess by the way.

 

Here's a picture of a Laguna front wheel bearing with a broken ABS magnetic ring.
As you can see the magnetic ring is very thin and is easily broken or damaged that's why extreme care must be taken when fitting the bearing, obviously it has to be fitted the correct way around with the magnetic ring facing the sensor.

I suppose wear on the bearing maybe could cause the magnetic ring to become damaged.

A good quality replacement bearing should ideally come with a plastic protective cup type cover over the magnetic ring end to protect the bearing in transit.

Cheers.

 

Well

I think I have decided that when the car goes into the garage for the bottom ball joints on wednesday, ill ask them to to the left hand bearing as well !

I just hope its not something stupid like i need my hub degaussing (de magnetising), cos its got magnetic !

good trace

not so good trace

photos direct goto https://lh5.googleusercontent.com/-tDwhe9cKLRw/ULtyPsjnL1I/AAAAAAAAGjQ/QwJzGVfULHA/s480/DSC00537.JPG

 

I'm no expert on this stuff but if you're missing pulses I'm pretty sure that will cause the problem.

Can you see any damage to the magnetic ring?

Do you think that you could have hit it when drilling out the old sensor?



I would think the garage would be aware of how delicate these bearings are so should know how to fit them and the precautions to take. Be aware that they can be damaged whilst being installed if not treated with the utmost respect, so if by chance they fit a new bearing and the ABS problem remains it still could be the bearing causing it!
I've read of bearings having damaged magnetic rings straight out of the box, that's why the better makes of bearing comes with a protective cover over the magnetic end.



Cheers.

 

Can you see any damage to the magnetic ring?

Do you think that you could have hit it when drilling out the old sensor?

I cant see any damage, but if the 407 is like the Laguna bearing they look easy to damage.

Yes i could have hit it or that bit of debris could have got it !.



I have 4 current theories
1) the magnets get weakened over time, like ever time you go over a pot hole
2) I damaged it with the drill
3) Ive magnetised the hub.

I think 2) is most likely

ill let you know what happens on wednesday !

 

As Toady has mentioned garage should know what they are doing but I have heard of bearings been pressed in the hub the wrong way round

GSF supply a cheapish bearing and in the notes it says to ensure bearing is fitted the correct way round, but it doesn't show which way to fit it

 

You may have slightly scuffed the magnetic ring with the drill bit, I've not seen the set up so I don't know if it's possible to hit it through the sensor hole. Maybe as a part of the sensor came out of the other end of the hole it hit the magnet.

I've heard that the GSF bearings are poorly packaged with no protective cover on the magnet end, a guy that fitted one on a Laguna had to replace it as the magnetic ring wasn't working but that could have been down to loads of things, who knows.

It's easy to identify which side is the magnetic ring, just use anything metal (paper clip etc) and it will stick to it.


Yeah let us know how you come on.


Cheers.

 

I got the car back this evening, complete with MOT and lacking an illuminated abs light.
The garage kept it last night, they could not get a new bearing in time yesterday.

They showed me the old bearing, it had 2 shiney bits which might have been from my drill.

So hopefully that's the end of this peugeot 407 story, apart from the bill !

Thanks to everyone who advised me through this adventure

 

Good to hear that it's all fixed and working now :thumb:

Yeah it does sound like maybe the drill bit may of scuffed the magnetic ring, I doubt it would take much to damage it given how fragile they are.

We all live and learn mate so you now know if you ever have to drill a sensor out again to try and keep away from the bearing if that's possible. If it's any consolation I would have done exactly the same and just drilled it out not thinking that the bearing would ever come to any harm...it's a stupid idea having the magnetic ring as part of the bearing if you ask me.

Anyway at least it's fixed and you can put your tools away.

Just for info,
On the Laguna to clear an ABS fault the car has to be driven to a speed of approx 10 - 15 mph before the light goes out. Actually I'm not sure if it's speed or distance related but I know when I have had sensors disconnected the ABS light comes on, reconnecting the sensor doesn't put the light out but once you drive the car the light goes out.

Just thought I would mention that as I've seen this on a few cars, and if anyone is trying to fix a problem it's worth noting !


Cheers.

 

Sorry I forgot to post the invoice details
I supplied ball joints.
garage invoice...
new wheel bearing OE 89.76 +vat
fitting 45+vat
ball joints fitting 2 x £25
mot £40

total £261.71