Lots of dash warnings Abs, Seat Belt, Brakes and no speedo

I have had my wife's Diesel 2007 C3 in and out of the garage for the last five weeks. With problems getting worse and worse.
One morning a warning came on the dash Stop Brake error.
I had been intending to take the car to the garage as there had been a sort of binding noise at the rear, getting worse the faster it went.
Turned out the noise was from rear wheel bearing so these were replaced, also the rear drums and ABS sensor rings at the same time.
It was thought this had fixed the dash error. But a few miles later I was getting an error message ABS error.
To cut a long story short it has been in and out of the garage many times. Each time they "fix" it, it comes back and may be ok for a short while then more errors appear.

Now when ever the car is driven at some stage in the journey I get these errors.

Stop brake system error (with warning light under speedo area)
ABS error (with warning light under speedo area)
Seat belt error
Airbag error

The speedo shows no speed just dashes " - - "
The steering goes heavy like the power steering is not working properly.

The garage had an auto-electrician check out the wiring and sensors and these were reported as OK.

The suggestion is that it may be the ECU. Having checked out a replacement they are very expensive, especially just to try as that may be the fault.

Has anyone had these errors and found a fix.

Where can I get the ECU checked to see if it really is faulty? and then get it fixed?

I have seen ECU units on ebay but am not sure which one would be the fix for the above errors. Plus I think it would need reprogramming before it could be used on my car anyway.

Any help would be greatly appreciated, and as cheap as possible. I had to pay out on the same car last year to get a damage fuel injector fixed and am still recovering from that bill as it was burnt in!

I'd start with the basics of the electrics. Get the battery and alternator checked. Not on a C3 but on another car I've come across all sorts of problems with an ECU down to poor supply voltage. Make sure the battery is good and the terminals are well fixed and clean. The voltage from the alternator should be regulated, if it goes too high it can cause some really strange things to happen with an ECU.

The above might not show anything but at least its a good solid start to fault finding.

kilabyte wrote: The suggestion is that it may be the ECU. Having checked out a replacement they are very expensive, especially just to try as that may be the fault.

If anything, its the BSI that is giving these errors, rather than the ECU. But at the end of the day, you can't fit a second hand BSI, you need a new one or fit a complete second hand kit of BSI, ECU and Transponder as they are all security linked together. The other option is to have your BSI repaired.

Missing Lincs wrote:I've come across all sorts of problems with an ECU down to poor supply voltage.

If this turns out to be the reason, hopefully its not permanently damaged the electronics of the car. As Missing Lincs suggests, its best to start with the basics and to cure them first before potentially damaging replacement parts fitted.

kilabyte wrote:Where can I get the ECU checked to see if it really is faulty? and then get it fixed?

https://www.bba-reman.com/ are well know for testing and repairing BSI units found on the C3.

Still getting nowhere with this.
Had the components sent off to bba-reman and they all test as working as they should.
Had battery and alternator tested and all work as they should.
Had wiring looms stripped down and tested. All ok.
All connectors have been disconnected cleaned up, any grease removed and re-greased with correct, non conductive.
Still getting the usual errors showing, admittedly not all every journey but within a few journeys all the same errors showing.
Plus now a new error showing "Plip key empty".
One error that seems to be consistent when hooked up to the computer is that the rear nearside ABS sensors is faulty. This was replaced at the start of all this and the manufacturer have agreed to replace it with a new one to try.
So going to try that. But surely that would not cause all the other errors.
This is now costing a fortune in the garage trying to fix it. Plus it has been three months of not being able to use the car other than a few days when they have returned the car (still costing me insurance and road tax on it though).
Losing faith in Citroen, which is a pity as my Berlingo van is still going strong and no problems (one reason why I bought my wife a C3).
Anybody any other ideas?

kilabyte wrote:Stop brake system error (with warning light under speedo area)
ABS error (with warning light under speedo area)
Seat belt error
Airbag error

The speedo shows no speed just dashes " - - "
The steering goes heavy like the power steering is not working properly.

kilabyte wrote:One error that seems to be consistent when hooked up to the computer is that the rear nearside ABS sensors is faulty. This was replaced at the start of all this and the manufacturer have agreed to replace it with a new one to try.
So going to try that. But surely that would not cause all the other errors.

Hi kilabyte, thanks for the update. You may be surprised to hear that all the above are connected with the abs! The road speed is taken from the abs wheel rotation sensor and this info is fed to power steering ecu for speed sensitive variable assistance, airbag inhibit (so the air bag is only deployed over a set speed before impact), ABS function (obviously) and speedo. The seat belt warning is one that I am not sure of, but I wouldn't be surprised that its connected too. The seat belt warning is quite probably the seat belt pre-tensioners warning, rather than the 'you are not buckled up' warning I was thinking of. The seat belt pre-tensioners will be linked to the abs speed sensors, just as the air-bags are.

I would look for the wheel sensor signals with an oscilloscope at the ABS ECU, obviously its going to be tricky as the wheels will need to be turning quite quickly and running for a while to see that every thing is as it should be. This is quite probably why the problem has not yet been sorted.

C3CAR wrote:
Hi kilabyte, thanks for the update. You may be surprised to hear that all the above are connected with the abs! The road speed is taken from the abs wheel rotation sensor and this info is fed to power steering ecu for speed sensitive variable assistance, airbag inhibit (so the air bag is only deployed over a set speed), ABS function (obviously) and speedo. The seat belt warning is one that I am not sure of, but I wouldn't be surprised that its connected too. The seat belt warning is quite probably the seat belt pre-tensioners warning, rather than the 'you are not buckled up' warning I was thinking of. The seat belt pre-tensioners will be linked to the abs speed sensors, just as the air-bags are.

Fingers crossed then when they change the sensor for the second time it may all fall in to place and the errors stop. Really hoping this will be the case.
I will update when I get the results.

Fingers crossed then when they change the sensor for the second time it may all fall in to place and the errors stop.

Well, sensors don't tend to go faulty, they are pretty robust, hermetically sealed and designed to work for the life of the car. Not just ABS sensors, but cam and crank, all those hall effect solid state sensors. The usual is contaminated connector contacts then secondly a damaged bit of wiring after its not been refitted correctly following some work. Changing the sensor usually clears the fault of contaminated contacts, but so would some electrical contact cleaner.

Attached is a picture of the ABS ECU and the ABS control block fitted to the car (an original shape C3). Its low down, and quite exposed to water and dirt from the road. If changing the wheel sensor again doesn't cure it, next step would be investigate the ABS ECU connections with a view to cleaning and identifying the wheel sensor inputs.

Well swapping the sensor did not work. Was a bit clutching at straws anyway, but getting like that now as three months down the line trying to fix it..
Now re-connected all the sensor ECU and ABS controller connections. Cleaned up, blasted with air and emery cloth cleaned where possible. All wiring checked from end to end.
Reset fault codes.
Still not fixed it completely. Although a little progress. Only getting ABS faulty and Stop brake system error faults so far.
Really at a loss as what to do now. Got a big garage bill but still not fixed. Really I should not be charged surely if they have not fixed it.
The car runs great, just these errors showing. Which of course means it will not pass it's next MOT.

kilabyte wrote:All wiring checked from end to end.

How?

Just a visual inspection, or did you use a meter. Don't forget there will be some CAN wiring mixed up in the communication between the ABS ecu and the other ECUs.

Did you check inside the plugs on the ends of the cables for poorly crimped connectors?

kilabyte wrote:Cleaned up, blasted with air

That's a good thing to do and either the cleaning or removing and refitting has produced some results.

kilabyte wrote:emery cloth cleaned where possible

For future reference, I wouldn't emery cloth modern electrical contacts as they have a very thin electroplating which can be removed with emery cloth giving problems later down the years as they corrode.

kilabyte wrote:Really at a loss as what to do now.

I think you have progressed well, and whatever you have done looks like you are in the right department. Check the plugs/sockets as I mentioned above, use an oscilloscope to monitor the wheel sensor signal - over a range of speed and temperatures.

Get some 'real time' information to pin point when the ABS error occurs - when driving off or just starting the engine? or after a few miles?

Had enough. Still can't find the fault.
Spent way too much time and money trying to get this fixed, 4 months now.
Have been and bought another car (not a Citroen) as we need one that is reliable and usable.
Going to put the C3 on ebay as spares or repairs.
Going to loose even more money. But enough is enough.