Megane Braking Fault.

[Mark_L]

Have a Braking fault on my wife's Megane 2 175dci.

I backed out of a gateway and thd Braking fault came on. Previously had the abs light on.

Bought a genuine sensor from RPD, found the rh front sensor was cut through at the track rod. Also had blown the dash 10A abs fuse.

Tried a different uch,

Abs doesn't work. All feeds and earth's are present at the abs pump, the sensors are all reading through my cheap module. Except 1 reads at 1 per km/H where as the other 3 read at 1 per 10 km/h. Odd. Swapped both front sensors which hasn't changed anything.
It's still reading the same.

Driving me mad and mot next week please help!

@Red21

 

[Mark_L]

Forgot to mention the only fault code that comes up is C10CC

 

[Red21]

There is not a lot of advice I can give over a forum regarding ABS diagnosis as it requires direct monitoring & data reading to aid diag.
The fault code C10CC mean nothing to me without a context title or a DF code so the C10CC may be specific to the test equipment you are using
The ABS will not work if there is any form of a fault and as you appear to be able to communicate with the ABS/ESP computer with the tester you have that side of things seems Ok, but you can answer a few questions which may help to point you in a direction to check.

Besides the work you have done to resolve the ABS warning what other (tyre, brakes, suspension gearbox etc) work has been done in before the ABS warning illuminated & how long has the warning been on?
Is the felt panel just below the scuttle grill in the engine dropped/sagging?
Does the car smell damp inside or have you had any water ingress problems that has now been resolved?
Has the vehicle ever experienced a low battery voltage incident or disconnection?
What happens when any fault codes are reset, ignition switched off and then the vehicle re-started. Does the warning reappear without moving or does the vehicle have to move before any warning?

Not a lot of initial help but sometimes even the complicated of problems have simple origins

 

[Mark_L]

There is not a lot of advice I can give over a forum regarding ABS diagnosis as it requires direct monitoring & data reading to aid diag.
The fault code C10CC mean nothing to me without a context title or a DF code so the C10CC may be specific to the test equipment you are using
The ABS will not work if there is any form of a fault and as you appear to be able to communicate with the ABS/ESP computer with the tester you have that side of things seems Ok, but you can answer a few questions which may help to point you in a direction to check.

Besides the work you have done to resolve the ABS warning what other (tyre, brakes, suspension gearbox etc) work has been done in before the ABS warning illuminated & how long has the warning been on?
Is the felt panel just below the scuttle grill in the engine dropped/sagging?
Does the car smell damp inside or have you had any water ingress problems that has now been resolved?
Has the vehicle ever experienced a low battery voltage incident or disconnection?
What happens when any fault codes are reset, ignition switched off and then the vehicle re-started. Does the warning reappear without moving or does the vehicle have to move before any warning?

Not a lot of initial help but sometimes even the complicated of problems have simple origins

Thanks any help is appreciated,

So, yes the scuttle is sagging, but I have removed the abs pump connection and it is clean.

No water ingress that I know of
It hasn't had any mods before this happened. Lowered since.

Same as the battery, it did go flat but this was after this fault came up.

We only had the car a few weeks before this happened.

The warning has been on for a long time now, took a while to get the correct sensor as they all came up short.

Once reset, it's clear until I reach around 10mph, when I swapped both sensors over this morning, I drove the car with the front wheels off the ground and the fault didn't reappear apart from the traction light flashing. But as soon as I drove it on all 4 wheels, it came up as soon as I hit 10mph.

Thanks

 

[Mark_L]

A few screenshot of the video took. As I don't know how to put the video up.

 

[andybond]

Post the video to youtube @Mark_L then copy and paste the link here

 

[Mark_L]

Post the video to youtube @Mark_L then copy and paste the link here

Thanks Andy, Never done that before either.

I'll ask my son. Lol

 

[Mark_L]

Here we go!

 

[Red21]

If your scuttle panel has sagged the chances are water ingress into to the cabin or water into the actual ECU internal section of the ABS unit.
From those screen shots the problem does appear to be the RHF corner over reading, or the others are grossly under reading.
There are a few of problems that can cause that overspeed reading the first is damage or contamination of the magnetic target. There should be 48 "Teeth" so if your equipment has a target check command use that to confirm the number during one revolution by hand. If you haven't got this command you may have to visually and manually check the condition of the target which is not always easy as it can be tucked behind the driveshaft as it is part of the wheel bearing assembly.
Another is an actual wiring issue like corrosion within the loom from the connector behind the arch liner any where along the ABS loom to the main connector. A simple continuity test may not pick up this corrosion, but a voltage drop test method should.
The other problem is you have a wrong wheel or tyre size on that corner.
If its the remaining 3 that are under reading it is the same basic rules & tests as above but on those corners
A check that can be performed quiet easily, is to rotate each wheel by hand making note of the speed when spinning the wheel, but try and maintain the same rate of turn other wise you could mis-interpret the speed readings.
Just watched your video that cropped up whilst I was writing and from the looks of it the RHF is reading correct based on the amount camera shake & the reflection of scenery on your laptop so it the remaining three that are at fault, but still just a observed guess.
The tests & checks listed above are still valid but you may have a common cause that is affecting just those 3?
If it was just the rear I would say loom connector under the front passenger seat due to water/moisture damage but 3 ?
It is possible that a short circuit on one of those circuits is blocking/interfering the signal for the others but that would normally just affect either the front or rear pairs unless it is internal to the ABS unit!
The long shot is, that it is going to take time and systematic testing to locate and may involve removal of the carpet to check the wiring that runs inside to the rear.

 

[Mark_L]

If your scuttle panel has sagged the chances are water ingress into to the cabin or water into the actual ECU internal section of the ABS unit.
From those screen shots the problem does appear to be the RHF corner over reading, or the others are grossly under reading.
There are a few of problems that can cause that overspeed reading the first is damage or contamination of the magnetic target. There should be 48 "Teeth" so if your equipment has a target check command use that to confirm the number during one revolution by hand. If you haven't got this command you may have to visually and manually check the condition of the target which is not always easy as it can be tucked behind the driveshaft as it is part of the wheel bearing assembly.
Another is an actual wiring issue like corrosion within the loom from the connector behind the arch liner any where along the ABS loom to the main connector. A simple continuity test may not pick up this corrosion, but a voltage drop test method should.
The other problem is you have a wrong wheel or tyre size on that corner.
If its the remaining 3 that are under reading it is the same basic rules & tests as above but on those corners
A check that can be performed quiet easily, is to rotate each wheel by hand making note of the speed when spinning the wheel, but try and maintain the same rate of turn other wise you could mis-interpret the speed readings.
Just watched your video that cropped up whilst I was writing and from the looks of it the RHF is reading correct based on the amount camera shake & the reflection of scenery on your laptop so it the remaining three that are at fault, but still just a observed guess.
The tests & checks listed above are still valid but you may have a common cause that is affecting just those 3?
If it was just the rear I would say loom connector under the front passenger seat due to water/moisture damage but 3 ?
It is possible that a short circuit on one of those circuits is blocking/interfering the signal for the others but that would normally just affect either the front or rear pairs unless it is internal to the ABS unit!
The long shot is, that it is going to take time and systematic testing to locate and may involve removal of the carpet to check the wiring that runs inside to the rear.

Thanks, the rhf is working to the same as the speedo where as the others are recording the same just in different units, so going up 1 for every 10kmh where as the rhf is going up each kmh the same as the speedo.

Nothing has been changed from before it happened apart from the rhf sensor, which is now on the lhf.

Wheel and tyres are all the same. Even matching Avon's.

Guessing I need to find someone with Clip to see what is actually going on.

Is the connection under the seat under the carpet?

Thanks for all your help.

 

[Mark_L]

Any other connections I should be checking?

 

[Red21]

Yes, there are two connection blocks under the passenger seat /carpet which are prone to water damage if there is any water ingress accumulation.
Anyone with a dealer level diagnostic equipment should be able check target tooth if yours doesn't have it but most of the testing will be with a multi meter and circuit load testers.
A question I forgot to ask does the sensor speed change corner when you swap them around?

 

[Mark_L]

Yes, there are two connection blocks under the passenger seat /carpet which are prone to water damage if there is any water ingress accumulation.
Anyone with a dealer level diagnostic equipment should be able check target tooth if yours doesn't have it but most of the testing will be with a multi meter and circuit load testers.
A question I forgot to ask does the sensor speed change corner when you swap them around?

No, the speed stayed as it was after swapping the front sensors over.

What I don't understand is how they are in sequence but in the wrong units? It's like they're programmed incorrectly, because as the front right hits 20 the others hit 2, 30 - 3 all the way up. So they're kind of in sequence??

 

[Red21]

So the RHF data line always reads"correct" vehicle speed when the sensor is swapped left to right -right to left?
Have you got a screen shot of the actual fault code line please.

 

[Mark_L]

This is the fault that re appears?

 

[Red21]

Image link doesn't work or the image hasn't loaded correctly

 

[DaveL485]

So one sensor is reading right (which happens to be the corner you replaced the sensor on, but the reading does NOT move when you move the new sensor)

The other three are reading 1/10th of the correct value.

The main ABS block has been changed too.

The fault clears until the car is driven at >10kmh, when it comes back again. Assumedly as it's detecting the speed differential and erroring.

Rich are the ABS control units coded to the car itself or can they be interchanged?

 

[Mark_L]

This is the fault that re appears? View attachment 147101

Strange I can see it?

 

[andybond]

Strange I can see it?

Same. Suspect work firewall?

 

[Red21]

The abs unit is technically vehicle specific and is configured to that vehicle for tyre size,steering angle sensor and suspension type (spring colour code)
Even if the unit was replaced and not configured correctly the road speed reading for each sensor should still display the same data as each other. The tyre sizing is for the correct instrument panel speed display and injection ECU road speed data.