Citroen c4gp 2008 gearbox faulty + Handbrake (sometimes)

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MrStrange
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Citroen c4gp 2008 gearbox faulty + Handbrake (sometimes)

Post by MrStrange »

Hi thank you to anyone who is reading this

We have been having this issue for a while, but it's only getting worse,

I have plugged the car into Diagbox, which I purchased to clear the faults, in which I keep receiving two constant faults

Cruise control ( injection faults) which I'm not concerned about,


But the gearbox issue which is giving me a fault sating gear lever selector (P1718)

We've had the common issue where the car simply won't start up, but yesterday it got worse, where the gears changed on their own mid drive, and Reverse drove forward, and automatic drove in reverse.


Would appreciate any help possible please, as I know main dealer is going to rinse our bank account dry for a fault that is their fault!
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GiveMeABreak
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Re: Citroen c4gp 2008 gearbox faulty + Handbrake (sometimes)

Post by GiveMeABreak »

Unfortunately that may be your only option - I suspect you have the piloted manual gearbox. These can be difficult to diagnose and fix and are rarely cheap. What you need to appreciate is that some of the faults you describe can be related and symptomatic of another fault - for example the electronic parking brake. This is generally managed by the ESP ECU, which in turn feeds speed related info to the piloted gearbox ECU. So if there is a fault anywhere with one of these systems it can prevent some features working (like your cruise control) as a safety measure until the fault is rectified.

Clearing fault codes is not going to help one bit if the fault is still there. It will simply re-appear again.

The system needs a proper diagnosis and fault finding. It may be a simple matter of reprogramming the actuators which needs doing if the clutch has been replaced for example.
It may be a loose connection or a loose pin in one of the connections that is causing incorrect info to be sent along the network.

In the case of the P1718 fault, this is a signal coherence fault with the gear selector lever.

Possible suspects are:
  • Piloted manual gearbox ECU
  • Sealing of the connectors and harnesses
  • 28-way connector of the piloted manual gearbox ECU
  • 28-way harness of the piloted manual gearbox ECU
  • Gear lever
  • Gearbox ECU
  • Earth cable
  • Earth screw
So it needs investigation unfortunately. I would not waste your time or money taking it to a general mechanic with little or no experience with these given the complexity of the system. It may be cheaper in the long run to take it to a dealer (as they may well have more experience of this fault and may be able to get it resolved more quickly) than taking it from garage to garage.

Pop your VIN up so I can double check the system you have.
MrStrange
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Re: Citroen c4gp 2008 gearbox faulty + Handbrake (sometimes)

Post by MrStrange »

Apologies I have only just seen that this had been approved, thank you very much for replying, I have only just sent you a private message sorry about that

Thank you

I'll send the message here too

Hi mate, wondering if you could help me please,


I've been trying to fix a problem with my partners c4gp 2008 gearlever selector p1718 is the fault code,

I have replaced it with a secondhand one off ebay which worked for roughly 3 days,

After a continous 3 weeks of using diagbox to clear the faults just to get the car started to take the kids to school, I feel like I'm at the stage of scrapping the car and we have to just do the hour walk to school lol,

I have been trying to use diagbox to reprogram the gear selector, but every time I set the value to 0 it tells me the programming failed.

I've tried lexia in which it tells me function isn't available ( I also can't depressurise or bleed the actuator, unsure if that is an issue)

Would be extremely grateful if you had any ideas or advice please

If its easier to talk by phone or message my number is

**********

Thank you so much

Jamie


My vin number is

VF7**************[VIN obfuscated, can be read by forum staff]

would you happen to have any diagrams at all for places under the car I could check for suspected problems at all please

Thank you so much again
Last edited by GiveMeABreak on 09 Sep 2021, 21:16, edited 1 time in total.
Reason: Number removed from public forum for security / spam prevention.
MrStrange
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An update to my p1718 fault code c4gp 2008

Post by MrStrange »

Would just like to make an update on my situation,

So on Saturday I took the plunge and decided to take 1 final look at my gear lever selector, in which I suddenly noticed one of the sensors had two soldering points snapped, which wasn't previously there,

I saw a YouTube video about 4 weeks ago with someone soldering their gear lever selector to repair their p1718 fault, but I wasn't 110% certain I would be capable of soldering 16 small sections

Saturday afternoon I pretty much gave in and whacked out the soldering iron and resoldered all 16 soldering points,

Pulled out the secondhand Gearlever I purchased and plugged in the original one which I repaired, and the service light and gearbox faulty error disappeared,

Plugged into diagbox and cleared the previous fault and its been 3 days and the car has been running extremely well, no shuddering, no hesitation, no gears slipping, reverse doesn't drive forward, auto1 doesn't reverse! , the list goes on with the faults and problems this has occurred!

Finger's crossed the problem doesn't come back 🤞

Really hope anyone who reads this is as lucky as I was!


On a separate note so I ain't spamming,

On diagbox I was trying to use the reprogramming gear lever selector option, and once I enter the value 0 and click OK I keep getting programming failed,

Is there any fix for this problem at all as I can't seem to use alot of the features, such as bleeding, depressuring although I've got a full chip diagbox and tried on 5 separate laptops

Many thanks guys
Last edited by MrStrange on 13 Sep 2021, 22:01, edited 1 time in total.
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GiveMeABreak
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Re: Citroen c4gp 2008 gearbox faulty + Handbrake (sometimes)

Post by GiveMeABreak »

Glad you have found the issue - electronic faults like this often need a bit more internal investigation as you've found. Engine vibration can be a curse on electronic components and over time can crack or weaken dry solder joints - especially where these are pretty thin to start with.

The gear Control Counter only needs to be reset to '0' if the gear selector has been replaced, so as you've refitted your original that should not need doing.
MrStrange
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Re: Citroen c4gp 2008 gearbox faulty + Handbrake (sometimes)

Post by MrStrange »

GiveMeABreak wrote:
13 Sep 2021, 21:34
Glad you have found the issue - electronic faults like this often need a bit more internal investigation as you've found. Engine vibration can be a curse on electronic components and over time can crack or weaken dry solder joints - especially where these are pretty thin to start with.

The gear Control Counter only needs to be reset to '0' if the gear selector has been replaced, so as you've refitted your original that should not need doing.


Thank you I really hope the issue is now fixed, as I'll be at the stage of having no choice but to scrap the car, as currently in no position to hand over £750 to citroen for them to hazard a guess at changing the gear lever,

Regards to zeroing the gear lever, I tried to change the value back to zero on the second hand gear lever to see if that would reprogram it to this cars vin number as that still shows faults,

I was looking at buying a brand new gear lever from aliexpress for £89 ( came up to £114) with taxes and shipping, I wanted to see how this gearlever was for the next few weeks and if the fault was genuinely fixed,would like to invest in a brand new one either as a back up or as a complete piece of kind for my partners car as she's extremely anxious over driving the car at all now, I'm just worried that if I buy a new one and I still am unable to reprogram it

Also when all of this blows over I would like to buy you a drink for all the support you've provided me it's been absolutely appreciated more than you can imagine!

Many thanks mate
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GiveMeABreak
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Re: Citroen c4gp 2008 gearbox faulty + Handbrake (sometimes)

Post by GiveMeABreak »

No worries - glad you have it resolved. :-D

Just for info, the VIN rarely gets coded to anywhere other than the BSI and the Head Unit - It's only the other equipment with ECUs that tend to need certain parameters configuring. Other equipment may need calibrating, but as far as the gear selector goes, it's just resetting the gear counter on actual replacement of another unit.

I'd personally avoid Ali* for anything like sensors or knock-off fakes of OEM equipment on safety reasons alone to be honest. Stick to a working used one or new if possible for things like this. :wink: