Grand Picasso parking brake wiring fault.

[Stuart W]

Thanks so much for that info Marc.I seem to be missing the +ve supply to the position sensor on left rear wheel.As before it seems to be the supply wire between the ABS ecu and the under seat connector.I will try a bypass wire.

[GiveMeABreak]

No worries, hope it helps.

[Stuart W]

Thanks for your info Marc.It has turned out to be the ABS unit ECU.No connection to the sensor on the caliper motor on the lhs.Fortunately I had expected this as we were running out of other possibilities, I purchased a used abs block ( £46 on Ebay) from an identical model C4 Grand Picasso..My friendly mechanic offered to do the mechanical work if I would do the electrics.He had to lower the engine from its mounting on the drivers side and this gave a still restricted access to the ABS block.As soon as the plug was pulled from the abs and plugged into the replacement unit The handbrake came on as soon as the ignition was on.It is worth pointing out that if you try this substitution test that the handbrake will not release because the hydraulic pressure sensor is part of the original unit whiçh although still plumbed in, now has no electrical signal as the plug is now in the replacement unit! Once the brake pipes were transferred to the new ABS and bled, all went back to normal.
The location of this ABS block is crazy.Access is extremely limited unless you completely disconnect and lower the engine but with patience it can be done.It is great to have the car back again and I must offer grateful thanks to you guys for your guidance and the help with the wiring diagrams .

[GiveMeABreak]

Thanks for the feedback and the updates, glad you have resolved the issue and I agree a total pain in the rear to access!

[Stuart W]

HELP!!! I don't believe it... but just when I thought we had solved the parking brake issue with the replacement abs block , we now have an intermittent abs light, intermittent power steering after a few minutes.The mechanic re installed the old abs with no parking brake to check the abs coding.Could this be a coincidental fault or are the steering and speedo issues related only to the front wheel sensors .I am wondering if he disturbed the wiring to these front wheel speed sensors when the engine was moved?My other thought was are there separate 12 bolt power feeds to different sections of the abs ecu and is one of these missing
.. loose fuse or the like?

[GiveMeABreak]

It could be any of the issues you have described, so best to check for additional fault codes and post them up here.

[Stuart W]

There are now a whole host of issues as listed below.These are not from a Lexia but a Citroen/ Peugeot icarsoft CP v1.I am wondering if there is a fuse or relay playing up as there are engine issues here.
ENGINE
Temp fault no communication with abs/ esp ecu
Fuel pressure lower than reference value
Temp fault.No comms with systems interface
Temp fault No comms with power steering and ecu
Temp fsult.No comms withneteork voltage maintaining ecu
Temp fault.Open circuit vontrol of air mixer
Temp fault.Position of air mixer.Voltage of the component too high
Tempfault.Remote controlled triggering line fault.Request for wake up of ecu not plausible or absent.
Temp fault.Intersystems CAN error.

Link error to system onterface.
Most of these look like main engine ecu problems.
On the engine relay unit I have these errors.
Temp CAN fault.CAN positive supply present but central power switch positive supply absent.
This looks like a likely cause if anyone has any ideas re fuses or relays. I also have a temporary fault.Suspension and wheels CAN fault.
ABS system codes U1118Temp fault. Comms with BSI interface
C1391 Temp fault.Non confirmation of engine torque.
EPB . No codes but shows link error even with ignition on.
I notice tat the engine wont stop until you press the stop button for about 5 seconds.
This all looks like a communication problem. Any ideas?

[GiveMeABreak]

As a lot of these systems are integrated in that they talk to each other via the CAN network - all it takes is a problem on the network to trigger multiple errors. Whether this is a power issue from the supplies management or a wiring break / plug disconnection / disturbance is hard to say.

The U1118 fault is a comms problem with no communication with the BSI. This in turn can disable the following:

- Traction control with action on the engine torque (EASR) : End of the regulation in progress if the fault appears during the regulation, then deactivation of the function
- Deactivation of the ESP function
- Deactivation of the hill start assistance function
- Deactivation of the emergency braking assistance function (AFU)
- Deactivation of the "Stop and Start" function

Suspects are of course - the inter-systems CAN, the electrical connectors or the BSI.

My firt thoughts are to re-trace your mechanics steps when he was last working on it as I suspect he has upset something in the process.

[Stuart W]

Thanks Marc.Where is the BSI unit located please.

[GiveMeABreak]

The BSI is located in the passenger glovebox. Be very careful around here - this is the vehicle's master computer. I would suspect something in the engine bay seeing as this has happened since the block has been removed and refitted a few times. Check the supplies and engine fusebox fuses / connections and the wiring connector from the ESP / ABS block ECU. Check the pins and the socket as it has been known for the pins to become loose. Make sure the connections are nice and clean - use some electrical contact cleaner.

[Stuart W]

Marc, am I right to assume that the yellow lines on the diagrams are the CAN bus? I have checked all fuses several times and even re installed the original abs block but the multiple faults remain .I have checked the yellow line inter connections from bsi to fuse box and abs block.All good.I guess the engine ecu plays a part in this too.Do you know the CAN line pins used on the ECU and the pins they go to on the abs or bsi?

[Stuart W]

I wondered if there are any relays relevant to CAN relsted power supplies.

[GiveMeABreak]

The Yellow lines on the previous diagram 9035 / 9035 are the CAN wires

[Stuart W]

I have managed to clear down a large number of non brake related codes that were showing and was left with faulty rear abs speed sensor on both rear wheels.Having meticulously checked the wiring from both sensors to the abs block plug and found no fault, I replaced both sensors.I still have the following fault codes C0037 STATE PRESENT rear left wheel sensor
C003A STATE PRESENT rear right wheel sensor Under my icarsoft EPB tests it displays : no data link error check ignition is on.
Additionally, service light is on and stop button takes a 5 second push to stop the engine.
Could the BSI have become corrupted?

[Stuart W]

I have also just seen that on a manual diagnostic search that it shows no link to the BSI, please check that ignition is on.unless there is a relay or fuse fault the BSI is beginning to look suspect.