Citroen c5 x7 2.0hdi battery Management system

[martomasz]

Hello, I am having some trouble with my Citroën c5 x7 2.0 hdi 140hp. The vehicle experiences a loss of power and occasionally shuts off, but can be restarted. I recently discovered that the battery management system is disconnected (the black plug on the negative terminal of the battery). I'm not sure why someone would remove this plug. I have identified several faults in the lexia system. Is it possible that a faulty battery management system could be the cause of these issues? I attempted to reconnect the plug, but the software is still unable to establish a connection, so I suspect that it is not functioning properly. Thank you.

[GiveMeABreak]

This is probably the 'Battery Charge Status Unit'. It's purpose is to monitor the battery health and report this to the BSI to fine tune the energy management. This is normally connected to the negative terminal lead prior to the clamp which then goes onto the negative terminal. The device is quite secure so I'm not sure how this has become detached. I'm not sure this is the cause of your vehicle losing power though.

Do you have any other fault codes or any fault codes stored in the log?

[martomasz]

The plug was disconnected by previous owner. I have no contact with him. Disconnected and isolated with tape. The car gives various fault information, mainly esp, abs, Hand brake faults. Diagbox reading attached :

All cable conectors, earth connection are checked and ok. Bsi already replaced. Not getting any better. Thanks

[GiveMeABreak]

You've got a stack of faults there, too many for me to go through, CAN faults on the data network can be triggered if aftermarket equipment has been wired into the vehicle's wiring systems. The previous owner it seems has already dabbled with disabling the BCSU - and I wonder what else they have done...

As for lighting - make sure you have the correct good bulbs and that you have not put LEDs in place of halogens. Check earths and general condition of the engine fusebox wiring and the wiring to and from the alternator to the battery. Start with basics and work out, but it will be easier to eliminate issues if you don't have other issues to worry about like aftermarket equipment / LED bulbs.

Ignore the speed anomaly from the suspension ECU - that's a ghost fault triggered when using the diagnostic.

Some codes like the parking assistance - are easy enough to deal with - it tells you which sensor is at fault. The same for the Lane Departure Warning - it tells you which sensors are faulty or where there is an issue.

I would ignore the footwell lighting for now (as this may need a new bulb if not the LED ambient lighting). The mirror faults can be a red herring as these always show a fault (mine did yet worked fine).

Anything to do with the cruise control will be as a result of the ESP system. If there is an issue with the ESP system, then most associated functions will throw an error, like cruise, electronic handbrake, hill start etc.

[Stickyfinger]

...almost...everything effects the cruse control ime

[martomasz]

I have no issues with ESP, handbrake, or other features of the car, which leads me to believe that the reported faults may not be genuine. In my experience, if the car is functioning properly, then faults typically occur simultaneously, indicating a possible rapid voltage drop in the system. I have not installed any extra equipment or LED lights, and despite having driven over 30,000 miles with this car, I have found it to be unreliable. The only anomaly is the radio, which appears to have been replaced by the previous owner, and bears the Peugeot branding. I am curious if this could potentially interfere with the car's communication system.

There are no other problems with the car, just every few hours of driving it goes crazy, loose power and randomly turns off. Cables between battery and alternator are ok, the same fuse box. Couldn't find any issue there. Battery starts with no problems, even after a week during cold winter......

[GiveMeABreak]

So let's get the fault situation cleared up. The car won't report a fault unless there IS a fault!

Whilst it is true that some faults codes can be triggered as a result of other faults on the vehicle, it does not mean the faults are not real. You need to undertake some further investigation. The ESP system is integral to many of the vehicle's systems, so although you may say the ESP is fine, when a fault is triggered it may go into a backup mode, depending on which faults it is reporting. Some of the faults may be intermittent or temporary (it undertakes a self-check at the start of each journey).

So you can't discount these faults. The CAN BUS system and the LIN network connects certain ECUs together and if there is a data issue or fault along the wiring, then it can result in faults being recorded with the engine ECU, ESP system or BSI for example, as these are all linked together.

[martomasz]

I got your point, but.... The fault can be triggered because of another fault in communication system. Silly question, as the previous owner installed in Citroën a peugeot radio, (you start a car and see peugeot logo sitting in a Citroën), as a try we are driving with radio being turned off. Its the large screen version with navigation and Bluetooth, which can be only used for phone, not for music). However since radio is off, i had no issues. No faults as well. Am i going crazy, or can a radio impact motor performance?
If so, which component it is where the logo is saved to, ao i can replace. Thanks

[GiveMeABreak]

Hi the Peugeot logo can't be changed manually, but the Head Unit ECU will have retained the settings from the previous vehicle, so has not been properly configured to your vehicle which includes the marque (Citroen / Peugeot) being displayed. This needs Diagbox and some knowledge of how to use it.

[martomasz]

Just a short update, the fault seems to be corrected. The problem was a faulty Crankshaft sensor, other faults seems to be follow faults as the engine was cutting of. After replacing this sensor, car drives much smoother, no faults occur. Happy with my French car again!

BTW, the logo Peugeot or Citroen can be chosen by giving appreciate vin number in audio module via diagbox.