Crippled C5

[GiveMeABreak]

The 'Communication fault with the switch module at the steering wheel' means there is no communication with the COMMS unit (the unit behind the steering wheel that holds all the indicator, wiper and cruise / audio stalks and controls). Faulty COMMS units are common - (I had mine go on my 2001 C5 SX) - resulting in loss of electrical power - audio stopped, dash lights went dead and silence, exterior lights switched off etc. They came on again after a while, but quite disconcerting.

There are several multiplexed networks on the C5, each controlling different aspects of the vehicle systems. For the Mark I C5, specifically:-

The CAN Network mainly connects the powertrain systems to the BSI, like the Engine, Auto Box, Suspension, ABS & ESP ECUs.

The VAN Comfort Network connects the BSI to the Instrument Panel, Multi-function screen, Audio, CD Changer and to the Navigation, Parking Assistance & Air Con ECUs.

There are then VAN Body 1 and VAN Body 2 networks:

The VAN Body 1 Network connects the safety devices to the BSI such as the Engine Fuse Box, Switch Module at the Steering Wheel (AKA as the COMMS Unit as we discussed) and the Airbag ECU.

The VAN Body 2 Network connects the BSI to the Diesel Additive and Sunroof ECUs, plus the Anti Intrusion Alarm, and the left and right Door control Modules (which work the electric mirrors, electric windows etc.)

So from looking at the faults you describe, it would seem to be the VAN Body Network (s) that would indicate a fault.

I suppose the most cost -effective solution would be to double check all the fuses, maxi fuses and check the wiring as best you can first.

I don't want to start saying replace this and replace that - but the above info may help you categorise the issues to one of the networks.

New and Refurbished COMMS units can be got from these people:
http://www.peugeotpartsforsale.com/citr ... -com-units

But you may decide to bite the bullet and get the dealer to determine for sure if it is the COMMS unit at fault or the BSI - or the communication between them.

[metaplay]

Thanks Marc, that's a pretty exhaustive response to my problem. I'll run through all the fuses again before I bite the bullet and get the car towed to my least favourite dealer - I've given up work to look after my mother with dementia so cash is really short so I've tried to put off the expensive option as long as possible.

Many thanks again Marc, Alun.

[GiveMeABreak]

Dim problem Alun, at least you have a few pointers and at least the garage will know you have some idea of potential issues. Will it be Bassetts, Swansea you were thinking of going to?

[Peter.N.]

Did the car get damp internally while it was standing? this can upset the electronics, make sure it is thoroughly dry inside, leave the doors open on a nice day.

Peter

[metaplay]

Hi Peter, my car was left standing in an exposed spot on my parents drive from last Summer until January I think, nearly a year of hospital visiting and looking after my father at the same time made me lose track of time.

The C5 got a bit damp in the boot but not inside the main interior. It played up electrically like crazy and showed an engine management light and airbag light and kept going into eco mode so I changed the battery straight away and has only shown the two lights until it gave me this imobiliser fault and gone into this permanent ecomode.

Its been kept close up against my parents house to minimise the effects of the elements and stayed dry inside since.

[metaplay]

Hi Marc I had a bad experience with Bassetts in the past so I'm pretty reluctant to use them again unless I have to.

I've previously used Lloyds in the Hafod Swansea who specialises in Citroens and Peugots to fix a previous Xantia and was good - he was pretty expensive for an independent but he isn't Bassetts…

[GiveMeABreak]

I completely understand - We've only ever had issues with the Swansea branch were we bought our C3 from (turned out it had a rear crush to the door and underside when it was delivered off the transporter without us knowing). The repair was pretty poor as the paint kept bubbling which was the giveaway really! Had it re-done by them. We don't use the Swansea branch, but I've been going to the Carmarthen branch for 25 years+ now as I know the Ex. technician, now Manager there and always trust my cars to him.

It's true though, find a good place / person you trust and stick with them!

[wurlycorner]

Just reading through this thread.
I can't tell if you have tried the following since changing the battery;
Disconnect the battery and leave it like that for a good long time (days, if you can?). Meanwhile, fully charge the battery over a long time, on a trickle charger.
Then reconnect and follow the bsi reset procedure.

I know it might sound silly trying that, but it ensures that after the electronics have got themselves into a state (which they clearly have) all the electronics will definitely now have a chance to fully shut down, reset and then be started up by the correct procedure, from scratch (rather than trying to recover without a full reset).

Also, are you sure you have the right replacement battery? Is it definitely the correct size/capacity, Not a slightly under-rated one perhaps? Is it a good brand and does it measure as 12v after a full charge? (not got a dead/dodgy cell that's dragging it down?)

[metaplay]

Thanks Iain.

Yes its been left for days disconnected, a week at one point, and the battery charged frequently to full - over 12.5 volts but still the same illogical behaviour. I still can't believe that its crippling itself on two fronts, permanent eco mode and the immobiliser, at the same time. Can't open the window in eco mode and the key doesn't appear to interact with the car so the standard reset procedure isn't happening…

As I've moved in with my parents to care for them I use my father's C5 to drive him around so I could swap batteries with his car as a test.

Did a second run through all the fuses with a multimeter today and all were fine.

I'll check out the key using Lexia tomorrow and then I'll just have to get it towed to a specialist although I hope he can check out the key first himself.