C4GP Gearbox fault + Parking brake fault

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mike_2001
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C4GP Gearbox fault + Parking brake fault

Post by mike_2001 »

Hi guys.
I have a problem with my Citroen C4 Grand Picasso (2014) piloted gearbox. This problem came out nowhere without any warning.
After I've been driving the car for about 60 miles without any problems I parked it. In a few seconds, I tried to start the engine and move the car.
The car didn't start and on the car display appeared Gearbox fault: Have the vehicle repaired and Parking brake fault: Have the vehicle repaired.
I called someone with a diagnostic tool (not Diagbox or Lexia) and he said there is no communication with the gearbox. Possible causes: broken wire or gearbox ECU faulty. All the fuses are OK.

For four weeks I've been trying to find someone who can test/repair this gearbox control unit. No luck so far ...

I want to check the wiring but I don't have the wiring diagram and the wiring codes. Can anyone help me with this?

Thank you
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myglaren
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Re: C4GP Gearbox fault + Parking brake fault

Post by myglaren »

Post your VIN so that the correct diagrams can be located.
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GiveMeABreak
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Re: C4GP Gearbox fault + Parking brake fault

Post by GiveMeABreak »

You really do need the fault codes read from Diagbox. The EAT6 automatic boxes have a stack of fault codes and I won't have a wiring diagram for this box.
mike_2001
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Re: C4GP Gearbox fault + Parking brake fault

Post by mike_2001 »

Hi
Vin is: VF7**************[VIN obfuscated, can be read by forum staff]
I forget to mention: When I tried to start the car (and the car didn't start) the brake lights are staying on, the windows cannot be closed or opened and I cannot lock the car.
The only way to lock the car and turn off the brake lights is to disconnect and reconnect the battery terminal.

Thanks
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GiveMeABreak
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Re: C4GP Gearbox fault + Parking brake fault

Post by GiveMeABreak »

Ok, so this isn't an EAT6 box - you have the manual piloted 6 speed pain in the ar** box.

So this smacks of a wiring issue. I've heard similar problems of where the poor quality wiring looms are too tightly packed in the engine bay, causing multiple breaks in the wiring. But it may also be the engine fuse box. I will see if there is a common issue for the systems you have described that are not working. I'll report back in a while when I've had a chance to study it.

Be very careful about disconnecting and reconnecting the battery terminals - there is a procedure to be followed - not doing so will cause havoc with electrical systems.

BSI Reset / Battery Disconnect / Reconnect Procedure
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GiveMeABreak
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Re: C4GP Gearbox fault + Parking brake fault

Post by GiveMeABreak »

As I suggested, you really need to get Diagbox on this as it could be a million things

There are a stack of different fuse and supplies protection on these, but have a look at 1032 which is the BGPA unit. This supplies the Engine Fusebox, the BSI and the Piloted Gearbox ECU.

Fuse F2 = BSI
Fuse F9 = Engine Fuse Box
Fuse F26 = Pilted Gearbox ECU
1032 C4 Picasso.PNG
There are simply hundreds of diagrams - so we need to know what the fault code is first of all to give us some idea.
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Re: C4GP Gearbox fault + Parking brake fault

Post by RichardW »

Given the random electric faults, and that it is probably the original battery, I would stick a new one on first and see where that gets you.
mike_2001
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Re: C4GP Gearbox fault + Parking brake fault

Post by mike_2001 »

Hi guys
I found the issue. It was the gearbox ground cable. It was broken next to the gearbox end.
Now I need to replace this cable. The part number is 9677717680.

The question is: After I replace the broken cable I need Diagbox for checking and deleting the possible errors? Until now I couldn't find anyone with Diagbox.
On the eBay, the Diagbox software is 40-100 pounds. Is working?

I found this because after I checked all the fuses (all OK), I start to check the wires.

Thank you so much for your help.
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Re: C4GP Gearbox fault + Parking brake fault

Post by RichardW »

Well found! Hopefully it will just work after you reconnect it and switch it on. You may still get an engine fault message for a few starts, but it should go away once it realises the fault is no longer live.
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GiveMeABreak
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Re: C4GP Gearbox fault + Parking brake fault

Post by GiveMeABreak »

Yes, well done on troubleshooting this.
travsithedog
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Re: C4GP Gearbox fault + Parking brake fault

Post by travsithedog »

Bit of a thread ressurection but we have the exact same fault this morning - right down to brake lights on and unable to lock doors. Hopefully getting it recovered to loacl garage in the morning, I'll tell them to look at the gearbox ground first.

is this a known/common fault