ABS Wheel Sensor
Moderator: RichardW
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ABS Wheel Sensor
Hi There
New to the forum
I have a 2011 Grand C4 Picasso 1.6 HDI VTR+
Does anyone know if the front ABS Wheel sensor can be removed by *just* undoing the Torx bolt ?
I have got the bolt out no problem but the sensor doesn't move at all - I didn't want to force in case I break it.
It cant move towards the hub as it has a lug sticking out right up to the hub (i guess to stop it moving around in situ)
It cant move left as its plastic body at that end sits under the suspension metal work (wishbone?) (again i guess to stop it moving around in situ)
So is there a procedure to get it out? (some special wiggle?)
Or do I need to dismantle the suspension?
Thanks in advance
Any advice much appreciated.
Richard
New to the forum
I have a 2011 Grand C4 Picasso 1.6 HDI VTR+
Does anyone know if the front ABS Wheel sensor can be removed by *just* undoing the Torx bolt ?
I have got the bolt out no problem but the sensor doesn't move at all - I didn't want to force in case I break it.
It cant move towards the hub as it has a lug sticking out right up to the hub (i guess to stop it moving around in situ)
It cant move left as its plastic body at that end sits under the suspension metal work (wishbone?) (again i guess to stop it moving around in situ)
So is there a procedure to get it out? (some special wiggle?)
Or do I need to dismantle the suspension?
Thanks in advance
Any advice much appreciated.
Richard
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Re: ABS Wheel Sensor
Hi, and to the Forum. I personally cannot offer you any other advise but wait for a while; somebody with the right knowledge will be able to help you.
James
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Re: ABS Wheel Sensor
Nothing special - it is probably just 'stuck' in place with deposits over time. Assuming you are replacing the sensor, and not reusing it, a light knock should free it - but not if re-using.
Disconnect the connector (at "b"). Unclip the wheel sensor harness (at "a"). | Remove:
|
ESSENTIAL: Avoid knocking the head of the sensor.
Check the cleanliness of the wheel sensor (2).
Refit the wheel sensor (2).
Tighten the bolt (1) to 0,8 ± 0,1 daN.m.
Connect the connector (at "b").
Clip the wheel sensor harness (at "a").
Refit:
- The splash shield
- The wheel
- The wheel bolts
Road Test and read any fault codes.
Please Don't PM Me For Technical Help
Marc
Marc
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Re: ABS Wheel Sensor
Hi Marc and all
Thanks a lot for the speedy replies.
I'll give it a try.
I am not sure the sensor is broken yet so I'll be gentle with it at first...
I suspect the connector on the ABS module is the root cause as I have had trouble with that before.
Was considering swapping left and right sensors to see if the fault moves sides. (I used a Lexia to tell me the problem was the right side)
When I was looking at ABS problems a couple of years ago I found a Citroen website that you could pay for hourly visits and get full technical explanations on how to do stuff.
Do you know if that still exists? I cant it find anywhere now. (don't really want to pay but...)
Thanks again
Richard
Thanks a lot for the speedy replies.
I'll give it a try.
I am not sure the sensor is broken yet so I'll be gentle with it at first...
I suspect the connector on the ABS module is the root cause as I have had trouble with that before.
Was considering swapping left and right sensors to see if the fault moves sides. (I used a Lexia to tell me the problem was the right side)
When I was looking at ABS problems a couple of years ago I found a Citroen website that you could pay for hourly visits and get full technical explanations on how to do stuff.
Do you know if that still exists? I cant it find anywhere now. (don't really want to pay but...)
Thanks again
Richard
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Re: ABS Wheel Sensor
Instructions say it should just come out. From what I remember having removed them when doing wheel bearing (that bit that sticks out over the back of the bearing is the pick up as the track is in the bearing) they can be a bit tight in the hub when it is corroded a bit. At least you got the bolt out, first one I tried it just snapped off and I had to drill it out!
Richard W
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Re: ABS Wheel Sensor
I would (before trying to remove the sensor) use a multimeter to see what the resistance is, and then compare that against another sensor. Something else to try is to use a proper contact cleaner on the relevant plugs/sockets (at the sensor and ABS nodule ends), unplug/plug them in a few times, and see if that helps. The action (along with the contact cleaner) can help remove any surface corrosion on the plug/socket pins.
James
ex BX 1.9
ex Xantia 2.0HDi SX
ex Xantia 2.0HDi LX
Ex C5 2.0HDi VTR
Ex C5 2.0HDi VTR
C5 2.2HDi VTX+
Yes, I am paranoid, but am I paranoid ENOUGH?
Out amongst the stars, looking for a world of my own!
ex BX 1.9
ex Xantia 2.0HDi SX
ex Xantia 2.0HDi LX
Ex C5 2.0HDi VTR
Ex C5 2.0HDi VTR
C5 2.2HDi VTX+
Yes, I am paranoid, but am I paranoid ENOUGH?
Out amongst the stars, looking for a world of my own!
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Re: ABS Wheel Sensor
Thanks All for the further replies
I did try a resistance check and got 14 Meg Ohms on both left and right, the Lexia flow chart said replace sensor if greater than 2 meg Ohms!
So from that I guessed they were both working and the Lexia info is out of date or N/A
However, I have read you can damage ABS sensors with a resistance check if they are active sensor types?
Does anyone know if the ABS sensors in the C4 GP 2011 are active or passive?
(I think active looking at the circuit diagram as it says speed reference and speed for the 2 wires coming off the sensor - so one input and one output)
Thanks Again
Richard
I did try a resistance check and got 14 Meg Ohms on both left and right, the Lexia flow chart said replace sensor if greater than 2 meg Ohms!
So from that I guessed they were both working and the Lexia info is out of date or N/A
However, I have read you can damage ABS sensors with a resistance check if they are active sensor types?
Does anyone know if the ABS sensors in the C4 GP 2011 are active or passive?
(I think active looking at the circuit diagram as it says speed reference and speed for the 2 wires coming off the sensor - so one input and one output)
Thanks Again
Richard
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- x 9
Re: ABS Wheel Sensor
The contact cleaner sounds like a good idea too.
Just for info:-
2 years ago the brake pedal input pin 30 to the ABS Module was not making contact - I ended up fixing it by jamming a bit of telephone wire in the female end of the connector and then plugging it back in.
Not an ideal fix I know - I only did it to confirm the voltage on the pin while the connector was situ. - but it fixed my problem and I left it alone.
So I don't want to mess with that connector again! (Hence I am wondering if I have the same issue on pins 18 or 6 - RH ABS sensor wires.)
but maybe cleaning it will help all the pins.
Anyhow thanks again all.
Just for info:-
2 years ago the brake pedal input pin 30 to the ABS Module was not making contact - I ended up fixing it by jamming a bit of telephone wire in the female end of the connector and then plugging it back in.
Not an ideal fix I know - I only did it to confirm the voltage on the pin while the connector was situ. - but it fixed my problem and I left it alone.
So I don't want to mess with that connector again! (Hence I am wondering if I have the same issue on pins 18 or 6 - RH ABS sensor wires.)
but maybe cleaning it will help all the pins.
Anyhow thanks again all.
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- Joined: 15 Oct 2019, 13:13
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- My Cars: Citroen C4 Grand Picasso 1.6 HDI VTR+ 2011 - Bronzey Brown
- x 9
Re: ABS Wheel Sensor
Hi All
I managed to get the ABS wheel sensor out OK - you were correct - it was just stuck with the muck - teased it out by levering gently with a jewelers screwdriver down the edge.
Replaced it but sadly it didn't resolve my problem!
Still got "Parking Brake Fault", "ABS fault" and ECP fault showing on the dashboard.
Lexia saying Right Hand Speed Sensor signal coherence
I have checked the wiring continuity between ABS speed sensor connector in the wheel arch and ABS module - seems OK.
I have tried to "force" the connection inside the ABS Module connector with a wire bridge on pins 6 and 18.
So that leaves the the ABS module itself or the reluctance ring.
Anyone heard of the reluctance ring breaking? (it seems kind of sealed away inside the hub on the C4?) Si there anyway to check it?
Anyhow Thanks again to all for the advice above.
I managed to get the ABS wheel sensor out OK - you were correct - it was just stuck with the muck - teased it out by levering gently with a jewelers screwdriver down the edge.
Replaced it but sadly it didn't resolve my problem!
Still got "Parking Brake Fault", "ABS fault" and ECP fault showing on the dashboard.
Lexia saying Right Hand Speed Sensor signal coherence
I have checked the wiring continuity between ABS speed sensor connector in the wheel arch and ABS module - seems OK.
I have tried to "force" the connection inside the ABS Module connector with a wire bridge on pins 6 and 18.
So that leaves the the ABS module itself or the reluctance ring.
Anyone heard of the reluctance ring breaking? (it seems kind of sealed away inside the hub on the C4?) Si there anyway to check it?
Anyhow Thanks again to all for the advice above.
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Re: ABS Wheel Sensor
Usually if the sensor or circuit is giving trouble, then the light will come on key on and stay on. If it's the ring, then the light will go out at key on, but come back on when you start moving as the sensor reading goes haywire. If you've got lexia then you should be able to see the speed readings from each individual wheel. If it is the ring, then it is integral with the wheel bearing, so the whole lot needs to be replaced - and the bearings are nearly £100....
Richard W
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Re: ABS Wheel Sensor
Hi RichardW
Thanks for comment above about the ring,
yes I get exactly that,
So if I clear all faults with Lexia then drive...
The ABS warning light is not on when I start the car and drive but the message comes on after a few seconds of about 30mph
I also get ESP/ASR Fault, Parking brake fault coming up
Next time I enter the vehicle (after stoping and removing key etc)
I get parking brake fault upon opening the door (it disables auto parking brake - but parking brake still works OK on the button press)
I get ESP/ASR fault when start the car (it disables the ESP - orange light on the button)
but ABS warning comes again on after a few seconds of about 30mph
So I guess from what you describe above the fault occurs at first because of a faulty reluctance ring. (system cannot detect the speed of the right wheel correctly)
The wheel speed must input to 3 systems - Parking brake, ESP/ASR and ABS
This causes a fault to the stored for ESP/ASR and Parking brake but the for ABS it is checked dynamically every drive.
Does that make sense?
On Lexia it said Front Right Wheel 255 KM/H
Parking brake temporary fault
[also ABS is actually operating at low speeds - juddering felt on steering as brakes bring car to halt - this occurs until it the ABS knocks itself off at +30mph)
Does anyone have a procedure for changing the reluctance ring?
Thanks a lot
Richard
P.S This forum is great - cheers!
Thanks for comment above about the ring,
yes I get exactly that,
So if I clear all faults with Lexia then drive...
The ABS warning light is not on when I start the car and drive but the message comes on after a few seconds of about 30mph
I also get ESP/ASR Fault, Parking brake fault coming up
Next time I enter the vehicle (after stoping and removing key etc)
I get parking brake fault upon opening the door (it disables auto parking brake - but parking brake still works OK on the button press)
I get ESP/ASR fault when start the car (it disables the ESP - orange light on the button)
but ABS warning comes again on after a few seconds of about 30mph
So I guess from what you describe above the fault occurs at first because of a faulty reluctance ring. (system cannot detect the speed of the right wheel correctly)
The wheel speed must input to 3 systems - Parking brake, ESP/ASR and ABS
This causes a fault to the stored for ESP/ASR and Parking brake but the for ABS it is checked dynamically every drive.
Does that make sense?
On Lexia it said Front Right Wheel 255 KM/H
Parking brake temporary fault
[also ABS is actually operating at low speeds - juddering felt on steering as brakes bring car to halt - this occurs until it the ABS knocks itself off at +30mph)
Does anyone have a procedure for changing the reluctance ring?
Thanks a lot
Richard
P.S This forum is great - cheers!
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Re: ABS Wheel Sensor
It's part of the wheel bearing, so you 'just' change the wheel bearing...
Slacken the hub nut
Jack up, remove the wheel
Split the track arm ball joint
Unplug the ABS sensor and free the cable
Remove the brake caliper / pads / carrier / disc
Split the lower ball joint
Undo the 2 bolts holding the hub to the strut
Remove the hub carrier from the car - if it's the NS be careful to keep the drive shaft in the diff or the oil leaks out....
Remove the ABS sensor
Drive / press out the hub (which will come with outer track still attached!)
Remove the circlip (yes, that rusty mess that used to be a circlip on the back of the bearing) - not so hard here as the ABS sensor allows a gap to start worrying at the back of the clip
Press out the bearing from the hub
Press in the new bearing, ensuring that the magnetic side goes inboard
Fit the new circlip
Use a blind bearing puller to remove the outer race from the hub (or cut it with an angle grinder till nearly through then break it with a cold chisel)
Press the hub back into the bearing
Refit the ABS sensor, then refit the hub back to the car and build it all back up.
I've done a few with a threaded bearing puller, but it needs plenty of muscle, and usually a good welting with a big hammer to get the bearing moving!
Slacken the hub nut
Jack up, remove the wheel
Split the track arm ball joint
Unplug the ABS sensor and free the cable
Remove the brake caliper / pads / carrier / disc
Split the lower ball joint
Undo the 2 bolts holding the hub to the strut
Remove the hub carrier from the car - if it's the NS be careful to keep the drive shaft in the diff or the oil leaks out....
Remove the ABS sensor
Drive / press out the hub (which will come with outer track still attached!)
Remove the circlip (yes, that rusty mess that used to be a circlip on the back of the bearing) - not so hard here as the ABS sensor allows a gap to start worrying at the back of the clip
Press out the bearing from the hub
Press in the new bearing, ensuring that the magnetic side goes inboard
Fit the new circlip
Use a blind bearing puller to remove the outer race from the hub (or cut it with an angle grinder till nearly through then break it with a cold chisel)
Press the hub back into the bearing
Refit the ABS sensor, then refit the hub back to the car and build it all back up.
I've done a few with a threaded bearing puller, but it needs plenty of muscle, and usually a good welting with a big hammer to get the bearing moving!
Richard W
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Re: ABS Wheel Sensor
Thanks a lot for that Richard W.
Just need to find time to have a go...
Richard A.
Just need to find time to have a go...
Richard A.
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Re: ABS Wheel Sensor
I've got one to do on my 3008 as well - same design. It hums a bit over 60mph, not bad enough to break the tools out yet!!
Richard W
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Re: ABS Wheel Sensor
Just to conclude this thread, it was the wheel bearing (or at least damaged reluctance ring inside it).
Sadly, I didn't have an opportunity to have a go myself in the end, local garage charged me £190
But I am back on the road ready for the MOT in 2 weeks time!.
Thanks to all who helped.
Out of interest any know what happens to these bearing/rings to make them go faulty? (only done 63K!)
Richard A
Sadly, I didn't have an opportunity to have a go myself in the end, local garage charged me £190
But I am back on the road ready for the MOT in 2 weeks time!.
Thanks to all who helped.
Out of interest any know what happens to these bearing/rings to make them go faulty? (only done 63K!)
Richard A