Grand Picasso parking brake wiring fault.

[Stuart W]

Does anyone know where the calliper motor harness connects at the engine compartment?
I have a C1562 error code but the usual area where damage occurs to the wiring under the wheel arches appears to be ok.I would like to test continuity from the calliper motor connector through the rest of the harness if I can locate it in the engine compartment.

[Stuart W]

I have checked the wiring from the left hand rear wheel to the connectors under the central rear seat and all is good up to there.The red wire from the rear wheel then becomes a blue with white stripe from this connector onwards to the front of the car.I have been unable to see an abs controller anywhere under either wheel arch.Does anyone know where the ESP or ABS units are on this 2015 C4 Grand Picasso blu hdi?

[Stuart W]

I have an open circuit wire from rear left hand wheel parking brake actuator motor.Not the usual wire break near the wheel arch but somewhere between the ESP and the connectors beneath the rear seat.I have spent 2 days trying to get wiring diagrams(wasted £26 buying a Haynes online manual which was totally useless) I am down to tracing wires by colour , blue with white stripe on this case but where is the ESP unit? I have removed both front wheels and inner mudguards but there is nothing there.Help anyone?

[Hell Razor5543]

Ignore the wire colour codes, as it is not unknown for them to change along their length. There will be number codes printed on each wire, and this will remain the same throughout the full length of the wire.

[GiveMeABreak]

The ESP unit is combined with the ABS system. The ECU is part of and sits on top of the hydraulic brake block. On this vehicle is it located behind the driver's side wheel arch, but is hidden inside a compartment. There is not much access and you may not be able to check the ECU without removing the entire block - which means scuttle, windscreen surround, under engine shielding off to get to:

[Stuart W]

Thanks. I have located it but rather than being under the wheel arch it is on the bulkhead in the corner behind the engine on the drivers side.!! Can barely reach it with fingertips so it is beginning to look like an engine out .job.Anyone else had any dealings with this.It seems a crazy place to put an electrical module.

[GiveMeABreak]

This is the fault descriptor - not a lot of help, but I would still focus on the caliper areas and connectors there as they are more exposed to the elements and harsh vibrations. Unlikely to be the ESP ECU itself, as these are quite robust, but no harm in checking the connector pins are secure if you can reach them. The same goes for any connectors at the rear. There have been cases here where on closer examination of the sockets and pins, one or the other is loose and causing issues.

Fault Code:	C1562 00
Description of Fault:	Electric parking brake (FSE) actuator sensors: Not characterised. Fault not confirmed on the sensors of the motorised brake calipers. The time for recording the fault code is 200 milliseconds
Conditions for Fault to clear:	Ignition on (For at least 5 seconds)
Downgrade Modes whilst Fault is active:	Checking of the motorised brake calipers: Only loose Deactivation of the "Stop and Start" function. Warning lamp "Auto P Off" and orange warning lamp "(P)!"
Symptoms:	Parking brake faults
Suspect Areas:	ABS/ESP ECU Electrical harnesses Connectors

[Stuart W]

Thanks again Marc.I can confirm that the connections from both rear wheels are ok up to the connectors under the middle rear seat.From there to the esp block there is one wire reading completely open circuit.If there are no more intermediate connectors then it must be broken or perhaps not making contact at the ESP block connector.Its just such a nuisance that the plug is so inaccessible.This is my 4th Picasso in 20 years and the only one that has been a problem.This being the second electrical issue in 2 months.The battery management unit failed on that occcasion flattening the battery.

[GiveMeABreak]

Do you have the VIN for me (automasked on post submission), I can't guarantee I'll have the wiring for this model, but worth a try.

[Stuart W]

Thanks again. The VIN is VF7**************[VIN obfuscated, can be read by forum staff]

[GiveMeABreak]

OK, unfortunately, I only have a few pictures of the general locations of the harnesses and the interconnections, but as for the wiring, no codes for the wires, so I can't tell you the designations.

These may help you:

Click on the smaller images to magnify them.

Main Wiring Diagram for the Parking Brake, but it shows you the motors on the calipers (7096 - rear left & 7097 - rear right).




This is the same, but the wiring connections to the harnesses and interconnections


These are the locations

Harness Locations	Interconnections Locations

[Stuart W]

Thanks again Marc.I will have a go at getting the multipin connectors out of the ABS unit to check the continuity of the suspect wire.

[Stuart W]

It looked like it might be the abs block so I bit the bullet and took it to a Citroen / Peugeot electrics specialist who after 4 days told me only what I already knew about the fault but some how managed to introduce a new parking brake fault on the right wheel as well.
Having a look at this myself now.Does anyone know about the sensor connections on the 2 thinner wires of the actuator motor? What sort of sensor is it and what is it sensing? My original fault pointed to the left side rear wheel.I have swapped over the left and right actuators and now l have a fairly general fault code of C156c motor actuator sensor.

[Doo]

It looked like it might be the abs block so I bit the bullet and took it to a Citroen / Peugeot electrics specialist who after 4 days told me only what I already knew about the fault but some how managed to introduce a new parking brake fault on the right wheel as well.
Having a look at this myself now.Does anyone know about the sensor connections on the 2 thinner wires of the actuator motor? What sort of sensor is it and what is it sensing? My original fault pointed to the left side rear wheel.I have swapped over the left and right actuators and now l have a fairly general fault code of C156c motor actuator sensor.

Looking at Marc's diagram, if the wires are running under the rear seat bases, it is entirely plausible that the base may have had an uneven weight, whatever, damaging the harness. I have come across this on many occasions in different vehicles. I tend to cut the damaged section of wire out of the equation and solder & heat-shrink a new section in. As long as the wire gauge is the same it wont affect the BSI. Sometimes I simply cut the bad wire & leaving it in place so future investigations can see what was done.

There is NOTHING worse than a fault such as this because you end up not seeing the forrest for the trees...

When I first got my Range Rover, the driver window went down and that was it. Stuck! I had the door apart (first to get a jumper wire on to raise the glass) and found no issues. There are sub stations for each door so I got a spare one only to find it was also ok. I could hear the relays clicking on demand, but no "up" only down I was able to measure 12v at the motor, so why not up?

Then it hit me, there was volts, but not enough amps!


Eventually I discovered the drivers carpet had been damp for a long time and because some glue sniffing engineer thought it would be a great idea to install the BECM (BSI) under the drivers seat, next to wet footwear, it had allowed grotty (no doubt salty) water to seep into the multi-plug for the door electrics. I pulled the plug and saw two green pins!! Cleaned them with the mouse tail file and Robert was indeed my mothers brother

I realise this may not help your situation, but then again, it may

Good luck

[GiveMeABreak]

I can't tell you which wiring code is which unfortunately on this model, but if there is a fault with one of more of the caliper motors, I suspect a replacement may be necessary as everything is internal to the units:

These are the wiring functions of the 4 way connectors:

Number of channels	Allocation of the tracks of the connector
1	Supply of the electric motor of the motorised caliper
2	Signal (+) from the position sensor of the electric motor of the motorised caliper
3	Signal (-) from the position sensor of the electric motor of the motorised caliper
4	Earth

But, the wiring can be identified from the plug here:

As for the sensors, they use a magnet and detecting cell very much like the ABS system to determine whether the handbrake is in application or the release phase.

(2) Motorised caliper motor. "a" 4-way black connector. "b" Gear wheels. "c" Magnetic target. "d" Detecting cell. "e" Electric motor of the motorised caliper.

"c" Magnetic target. "d" Detecting cell. "e" Electric motor of the motorised caliper.

The position sensor of the electric motor of the motorised caliper consists of an element that is sensitive to the changes in magnetic field of the target "c" and a detector cell that generates the electrical output signal "d".

"C" Air gap.
"N"North.
"S" South.
"c" Magnetic target.
"d" Detecting cell.
The position sensor of the electric motor receives a magnetic frequency sent out by the magnetic target "c".
The succession of north and south poles from the target switches the electrical output from the sensor, indicating whether the phase is application or release.

Hopefully this will give you a better understanding of the operation.