In a 2007 C5 Hdi 2.0 I have 'Power Steering Faulty' showing up with heavy steering, so I assume the pump isn't firing up. Lexia diagnostics tells me 'No Communication with ECU' with the electro pump ECU.
When I back-probe the com lines at the electro pump ECU I can see the signal below, so I don't know if perhaps I have a bad ECU or if the BSI is sending bad signals, because I don't know what good signals should look like.
How old is the battery? If the battery is old it may be that it is not 'waking up' the various ECUs as you turn on the ignition. Then, as the ECU was not 'available' during the ignition sequence, it does not get recognised when there is enough power to turn on the power steering ECU. When I left my C5 for about a fortnight I had the same problem that you are experiencing when she first started, but after I drove her for about 30 minutes the battery got enough of a charge that (when I stopped to fill her up with fuel) when she started again everything was working properly.
The Citroen C series are very electronic dependant, and a weak battery can cause all sorts of problems, as the electronics cannot get enough power to work properly.
James ex BX 1.9
ex Xantia 2.0HDi SX
ex Xantia 2.0HDi LX
ex C5 2.0HDi VTR
ex C5 2.0HDi VTR
ex C5 2.2HDi VTX+
Yes, I am paranoid, but am I paranoid ENOUGH?
Out amongst the stars, looking for a world of my own!
Hell Razor5543 wrote: 13 Aug 2023, 11:12
How old is the battery? If the battery is old it may be that it is not 'waking up' the various ECUs as you turn on the ignition. Then, as the ECU was not 'available' during the ignition sequence, it does not get recognised when there is enough power to turn on the power steering ECU. When I left my C5 for about a fortnight I had the same problem that you are experiencing when she first started, but after I drove her for about 30 minutes the battery got enough of a charge that (when I stopped to fill her up with fuel) when she started again everything was working properly.
The Citroen C series are very electronic dependant, and a weak battery can cause all sorts of problems, as the electronics cannot get enough power to work properly.
Thanks for the reply, I am suspicious of the battery and before posting I have put it on charge overnight. Last time I had 'erroneous' errors in this car a few years back it was the battery slowly dying so what you suggest is consistent with that experience. Interesting that the voltage being slightly low can prevent ECUs from waking up, I never knew what the mechanism for these errors was but that makes a lot of sense now!
Sounds like I need to keep the charger hooked up to the battery and maybe with a battery monitor on it as well when I next test the car and perhaps that will tell me what's going on. I'll report back in 24 hrs.
After trying a new battery I got miserable because it changed nothing. The electro pump and its ECU are receiving healthy well over 12v but no response on the coms lines.
Do these ECUs tend to die? I tried finding one a used one but so far no luck for this model. Repairable perhaps?
