C4 Grand Picasso 2007 Parking Brake Intermittent faults

[GreyElephant]

Please help - I need this resolved urgently for my son's driving test next week, they don't allow active faults on the dash!
I have a C4 Grand Picasso 1.6HDi Manual 2007, owned since 2009.

The parking brake has started exhibiting intermittent faults, displaying large 'P' and small 'P in triangle', plus warning message about parking brake fault.

1st fault event - Occurred whilst driving at town speed after one mile.
2nd fault event - Occurred when parked and simply opening the driver's door, but auto-release still worked ok when pulling away.
Faults self-heal after going to sleep.

After 1st fault event, I scanned with Topdon and cleared DTCs.
After 2nd fault event, scanned again.

05FF - THIS ONLY FLAGGED ON FIRST SCAN, THEREFORE POSSIBLY NOT RELEVANT?
Built-in Systems Interface(Bsi) - Unexpected Re-initialisation Fault Coming From The BSI - Not Characterised

U1219 - THIS FLAGGED ON BOTH SCANS, THEREFORE IS PROBABLY RELEVANT
Anti-lock Brake System - Fault Automatic Release Of The Electric Parking Brake. Data Invalid - Intermittent

C1555 - THIS FLAGGED ON BOTH SCANS, THEREFORE IS PROBABLY RELEVANT
Electric Secondary Brake - Fault In The Activation / Deactivation Control Of The Electric Parking Brake. Short Circuit To Positive Or Short Circuit To Earth - Intermittent

I would appreciate any help, guidance, pointers, methods, etc.

Many Thanks, David

[xantia_v6]

Does the parking brake still work, regardless of the errors? (this may help diagnosis).
After clearing the fault codes, did they come back immediately, or only after the parking brake was activated?

[RichardW]

Are there any faults in the engine ECU - particularly with regard to the EGR valve? I chased that one for a long time....

However, I think in this case C1555 might be the one - and it possibly relates to the dash switch - is the light on it flickering? Fortunately this is cheap and easy to change! I had to put one on my 3008 last year, from memory it was about £7 and about 3 mins to change it

[RichardW]

[mickthemaverick]

Considering the number of people listed in the credits at the end of that video I think, although the info is useful, it was very poorly filmed and put together.

[PaulC5]

A lot of Picassos get parking brake faults which are due to the wiring to the back getting damaged. To find it needs it checking from the back towards the front.

[RichardW]

A lot of Picassos get parking brake faults which are due to the wiring to the back getting damaged. To find it needs it checking from the back towards the front.

Yeah, but not on a MK1.... different system - central motor under the left front seat with single bowden cable to the rear which splits on the rear axle to separate bowden cables to each caliper.

[RichardW]

Considering the number of people listed in the credits at the end of that video I think, although the info is useful, it was very poorly filmed and put together.

I didn't actually watch it, just found it for reference and stuck it up!

[GreyElephant]

Hello, thanks for the quick responses.
There were a couple of other fault codes, the others not related, radio and glow plugs.
After clearing the faults, I didn't rescan until after the fault occurred again, then after the next fault I scanned and cleared them again.
When the fault was showing I think the auto operation of the brake worked ok, but not manual operation, not 100% sure of that though.
I haven't noticed the light on the manual switch flickering at all.
I think that answers your questions as far as possible.
Does that provide any useful pointers?
Much appreciated.
Thank you.
David

[RichardW]

If the C1555 is permanent, I'd just stick a new switch in - it's cheap and easy and will probably fix it.

[GreyElephant]

Update:
The next journey of 11 miles, no problem.
I've just scanned it again - The previous faults have NOT RETURNED since I cleared them, so they are not immediately returning and they are not permanent.

BUT NOW THERE ARE 2 NEW DTCs:
- P0B8A - Control Panel - All Or Nothing Input Button NO. 3 Jammed. No Signal
- P0B88 - Control Panel - All Or Nothing Input Button NO. Jammed. No Signal
- Plus I measured battery voltage: 12.75V (engine off) 14.4V (idle).

Do you have any idea what these new DTCs mean?
Are they related to the parking brake in any way?

Is it best to just replace the switch regardless - I don't know if the cheap ones on eBay are worth the risk.

Many Thanks, David

[GreyElephant]

Interesting update, I removed parking brake switch and disconnected:
- Auto operation still worked ok
- Dash warnings were same as original post
- Although DTCs cleared, U1219 and C1555 flagged again as per original post
- This makes this switch a likely suspect

I opened the switch module and found that the pins for the connector were a push-fit into the double-sided through-plated PCB, not soldered. I guess that after 18 years there is a risk that these mechanical dry joints could become high-resistance or intermittent (I believe that this is a recognised failure mode?).

We soldered the pins to the PCB pads, re-tested and working ok 'at the moment', cleared DTCs, and now wait and hope no further issues, but it was previously intermittent, so difficult to reliably prove whether this is now reliably resolved.