U1218 on Citroen C5 X7 1.6 HDI

[GiveMeABreak]

@Iankai1:

Ok, so you can see that the faults are likely connected. Your P1A99 is saying there is an over-voltage issue, at least concerning the Stop Start system, and this may be confirmed by the second fault regarding the CAN network.

So have you attached anything to the vehicle such as after-market accessories, chargers / a battery conditioner, USB accessories or modified any connections or taken any electrical feeds of anything?

If you do have anything connected up, I would remove them, then clear the faults codes, and then take the car for a spin for 5 minutes or so. When you get back see if any of the faults have reappeared. Remember to do this in the order I suggest:

Remove any connected accessories
Clear Fault Codes
Go for a spin
Re-check faults on return.

If you have eliminated any accessories then it will need further checking by an electrical specialist, or get it to Peugeot.

Fault Code:	P1A99
Description of Fault:	Stop and start: Electrical network voltage too high. Addition of a voltage source: Voltage above 16V.
Conditions for Fault to clear:	Ignition On
Downgrade Modes whilst Fault is active:	Automatic restarting impossible following stopping of the engine (Requires restarting of the engine using the key).
Symptoms:	Problem with automatic restarting of the internal combustion engine Absence of automatic stopping of the internal combustion engine Malfunction of the Stop and Start switch or its LED
Suspect Areas:	Battery Onboard network

Fault Code:	U1218
Description of Fault:	Intersystems CAN: One of the parameters present in a datastream sent by the BSI is invalid. Faults in communication between ECUs on the CAN network. For this fault to occur, at least oneof the following conditions must be true: - Ignition switched on - Engine running
Conditions for Fault to clear:	Driving for 5 minutes
Downgrade Modes whilst Fault is active:	None
Symptoms:	Jerking/stalling Starting problem Lack of power
Suspect Areas:	Engine ECU Intersystem CAN network

[Iankai1]

I have only had the car for a week as far as I can see there is no modifications I have checked all lights and they are standard no accessories fitted either the only thing which I can't figure out that looks out of the ordinary are 2 thin wires that are in the loom for the fuses on top of the battery I haven't got a clue what they are for

[Iankai1]

In the pic provided you can see the 2 wires which have been joined to additional connectors I have got a clue where they are for or if its anything to do with the ongoing problen

[GiveMeABreak]

Neither of those connections look official to me. Both the black and red wires look to have been 'spliced' into those yellow / cream wires and secondly, those cream wires themselves don't look right - even though they appear to come from inside the sleeve - they look far too thin to be attached to the supplies and protection unit which is where all the others go. So I wonder whether the cream wires have been added previously and then somebody has spliced off those....

In either case, they shouldn't be flailing about like that. I would get them separately insulated at the ends with some insulation tape and tie them out the way of anything else with a cable clip for now.

[Iankai1]

Sorry for asking so many questions but they wouldn't be anything to do with negative start stop black terminal on the battery as I don't have any wires going into it as I have seen on other images that ther is a wire sleeved in black as in the image below

[Iankai1]

By the looks of it I don't seem to have anything thing plugged into the battery charge status unit on the negative terminal

[GiveMeABreak]

Well that's interesting, and this is likely to be the cause of your fault codes.

The battery charge warning light comes on in the following cases:

• Battery charge status below 50% (Only during the vehicle’s first 12.5 miles/ 20 kilometres).
• Battery voltage higher than 16V for more than 3 minutes
• Battery voltage lower than 12V for more than 3 minutes

Considering the fault code descriptors above in my previous posts, if this was in fact disconnected, then it would of prevented any warning coming on.....

So here is the Battery Charge Status Unit. It is attached to the earth negative terminal of the battery.

Here is the 2 pin electrical connector:

Pin one is the LIN (Local Interconnect Network) and pin 2 is the battery positive supply.

So as the LIN network sends packets of data between a master ECU and other slave ECUs on the network, this is probably why there are faults as the master is not getting any info from the BCSU.

[Iankai1]

I actually think that had helped me a huge deal I have just got to figure out the wiring colours now that go to that plug I am beginning to think that these have been cut to disengage the stop start

[GiveMeABreak]

Unfortunately the colours are not going to help you here, as PSA can (and often do) use any colour. The wiring colours for the unit are marked MD, so non-descript and can be anything. I can only advise as above with which wire should be in which pin.

The Stop Start system is very voltage sensitive and although your vehicle should have an energy accumulator in it, the system relies on so many factors / pre-requisites being in place from the various systems before it will work. Just be very careful around the energy accumulator - never touch these without having discharged them first (just a polite warning).

So not sure where to go from here and why it was all disconnected in the first place...

[Iankai1]

I will try to figure that bit out .all I can say is thankyou so much for your help

[GiveMeABreak]

No worries, I do hope you can get it all back again!

[Iankai1]

Hi its been a while since I first asked about this fault but 2 months on and I still have the same problem I wired the battery charge status unit back in properly my battery charge tested at 94% with nothing running .the question is regarding diagnostics ,if its put on lexia will it tell me what module and where the electrical fault is or will it just say that there is a problem as it is now .thanks

[GiveMeABreak]

It will only provide you with the fault code, which can help with narrowing down the problem. Unfortunately because a fault can be either a physical fault with the sensor or device (faulty mechanical component) or it can be an electrical fault (so not working or working intermittently), or it can be a multiplexed network communications fault which is what most 'U' fault codes are.

In addition you can have peripheral faults that can be triggered as a result of another component which is not working. So if another component relies on data from another component that is faulty - then this component can also thro a wobbly as it's not getting the data it needs or out of range info.... so you see why it it not possible to nail the cause of fault down with 100% certainty.

[Iankai1]

Thank-you for your help I finally found the problem for the u1218 code and the p1a99 it was down to the bpga on top of the battery so I replaced the unit with no error codes and start stop now work . Thanks

[GiveMeABreak]

Great, thanks for the update.