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C4 Picasso ECU/ABS/CANBus fault

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Author Post
kbg2020   
Fri Jan 31 2020, 04:46pm
Member No: #55516
Joined: Jan 30 2020
Location: Manchester
Hi,

I am after some advice from you experienced folk. Looking to help save my Mum’s C4 Picasso 1.6 VTR+ HDi Automatic, Jan 2009 plate, 98k miles. ECU/ABS/ ESP/ CANBus fault(s).

Last MOT’d in June 2019 at 94k miles with no advisories. Bought in 2016 at 78k miles. No real problems until now. Bodywork good, just minor scratches, scuffs, skirt dent. Honest John valuation is around £2,000 - £2,500 if the current issue was fixed!

Car keeled over 3 weeks ago with Engine Management, ABS/ ESP fault, parking brake fault, service, stop, etc. Intermittent starting but wouldn’t drive. Called out RAC who could not resolve. They recovered it (drove short distance in limp mode) to her nearby local garage (West Yorkshire) where they have given her good service over many years and several cars. Garage has investigated over the last fortnight including OBD2 and related diagnostics by a reputable external mobile auto-electrician they use for such ECU issues. The recommendation was to try replacing the ABS pump and its control unit. A second-hand unit was tried in the car but it did not cure the problem. Seems to involve CAN BUS issues or the like. Garage suspects potential wiring issue deep in the looms / connections. Garage reluctant to spend any more man-hours as could be a big labour and parts bill. They aren’t recommending ECU testing. Say it is essentially an economic write-off. Car starts and idles OK (well it did today) but just cannot be driven with the faults unresolved.

A friend of mine who used to own a C4 pointed me to this forum and also to another forum thread with a video of similar problems. See the following link.He says not to give up entirely just yet without asking around.

- Click Here -

My Mum loves this car and will be sorry to see it go? Is there an economic means of trying to save it from scrappage / breakup? What do you folk reckon? Could this be a project for someone? Obvs would need collection from West Yorks (HX7).
Thanks in advance.
KBG.
rusky   
Sat Feb 01 2020, 05:42am
Member No: #27768
Joined: Oct 13 2012
Location: Hove
You need to see what fault codes are present. It could be a lot of things.
1 User said Thank You to rusky for this Post :
 kbg2020 (01 Feb 2020 : 11:25)
kbg2020   
Sat Feb 01 2020, 12:03pm
Member No: #55516
Joined: Jan 30 2020
Location: Manchester
Thanks.

Yes, that sounds logical. Unfortunately the (verbal) report is that neither the RAC recovery nor the Mobile Auto-Electrics & Advanced Diagnostics specialist (a reputable Halifax family firm) used by the garage could obtain any meaningful feedback fault codes from the OBD2 port using their diagnostic tools - not Lexia but similar/equivalent. The suggestion from the Mobile specialist to the garage was to try replacing the ABS pump unit with a second hand spare. This did not give any improvement in fault condition or diagnostics, and was removed / re-instated. The garage conclusion is potentially a CAN-BUS / wiring fault within the looms; which they advise would / could be throwing good money after bad to try and find a needle in a haystack.

I have no experience with the C4 (being a VAG and Mazda man), and only got involved yesterday to see if there was a way out of scrappage / breakage. Without meaningful fault codes it seems not.

TriumphGuy   
Mon Feb 03 2020, 01:20am
Member No: #47272
Joined: Jan 13 2017
Location: Halifax, West Yorkshire
I'm close by and I have Diagbox. I followed your link on the first post and I'm familiar with the guy who started that thread. I've seen his videos on his YouTube channel (LM Auto Repairs) and he has fixed C4 Picassos in the past. If nothing else, I can bring up all the fault codes which might come up with a direction. The first thing to do is to get the battery profesionally tested if it hasn't already been done. A failing battery can cause strange random errors. My next suspicion would be a wiring problem (broken wires or corroded connections).
1 User said Thank You to TriumphGuy for this Post :
 kbg2020 (03 Feb 2020 : 11:39)
kbg2020   
Mon Feb 03 2020, 12:01pm
Member No: #55516
Joined: Jan 30 2020
Location: Manchester
Thanks TG - I just got home (Manc) after work and read your post. I am not certain whether the RAC homestart and/or the HX7 garage did a proper battery test (I would have hoped so) but I will follow this up tomorrow and arrange if not. I will also PM you later this evening after dinner with further thoughts / details. My gut feel (after watching the LM-AR video) matches your experienced suspicions, which is why I am hesitant for the garage/my mum to throw the towel in the ring just yet. Cheers
TriumphGuy   
Mon Feb 03 2020, 03:14pm
Member No: #47272
Joined: Jan 13 2017
Location: Halifax, West Yorkshire
I've sent you a reply. I'm sure it is fixable and I'm sure that there is a cost-effective way. It should be possible to do the test with the battery in situ so that the alternator can be tested at the same time.
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 kbg2020 (04 Feb 2020 : 01:29)
TriumphGuy   
Sat Feb 08 2020, 06:09am
Member No: #47272
Joined: Jan 13 2017
Location: Halifax, West Yorkshire
We've been out to the car and it was showing hand brake and braking system fault errors on the display. I connected my laptop and it didn't pick up the VIN automatically. We couldn't read the VIN at the bottom of the windscreen because of condensation so we got it off the paperwork. Unfortunately, Diagbox wasn't able to communicate with any of the ECUs. My first thought was that the fuse had blown. We soon located the fuse in question which was fuse F5 on the battery fusebox. It should be 15A but there was a 5A fuse so that was replaced. We removed the battery hoping to get to the loom which looked like it had been repaired in the past. We checked another wire that had been repaired in the past and had to redo one of the connections. Unfortunately, it didn't make any difference.

Does anybody know why there's no communication with any of the ECUs through the OBD2 port? The car is a 2009 Picasso VTR+ with the 1.6HDi engine and the EGS transmission.
TriumphGuy   
Mon Feb 10 2020, 06:48am
Member No: #47272
Joined: Jan 13 2017
Location: Halifax, West Yorkshire
My next thought is to check the rest of the fuses to see if any are blown. I've come across situations where and apparently unrelated fuse has blown and it has caused problems elsewhere. After that, it will be a matter of tracing the wires from the OBD2 port to see if there are breaks. One of the multiplug connectors in the engine bay fusebox has had wires repaired in the past. Once we are able to get fault codes, that will give us some direction. We also did a "quick and dirty" test on the battery with a multimeter which may be past it's prime. The alternator seems to be working so the battery is either on the way out or just needs a charge. A proper test would confirm if the battery is in need of replacement. I've offered to recover the C4 Picasso to the OP's sister's house in Mytholmroyd where there is a driveway where it can be worked on. I have an A frame and my own C4GP is up to the job.
1 User said Thank You to TriumphGuy for this Post :
 kbg2020 (15 Feb 2020 : 01:45)
TriumphGuy   
Thu Feb 13 2020, 01:30am
Member No: #47272
Joined: Jan 13 2017
Location: Halifax, West Yorkshire
I've been doing a bit of digging around and I've found a pinout for the OBD2 socket.
- Click Here -
Pin 16 is battery power and pins 4 & 5 are grounds so these would be the first ones to check. This can be done with a multimeter or better still tested individually with a power probe. Pins 6 & 14 are the CAN high and low respectively and could be the reason that Diagbox was unable to read any of the modules.
2 User said Thank You to TriumphGuy for this Post :
 BigJohnD (13 Feb 2020 : 03:19) , kbg2020 (15 Feb 2020 : 01:45)
kbg2020   
Sat Feb 15 2020, 01:54am
Member No: #55516
Joined: Jan 30 2020
Location: Manchester
TG - thanks for your digging around on the OBD2 issue. All sounds a good approach to me. I have been working away 'darn sarf' (London) all week and am just back 'oop north' and catching up. I am planning to get the battery out and properly tested and I will be in touch regarding recovery to Mytholmroyd so we can work on it better. But this is all likely now to be after Storm Dennis has been through.
TriumphGuy   
Thu Feb 20 2020, 01:57am
Member No: #47272
Joined: Jan 13 2017
Location: Halifax, West Yorkshire
I reckon a comparison with a known good OBD2 socket would help with diagnosing the lack of communication. I've got my own C4GP which is a known good.
1 User said Thank You to TriumphGuy for this Post :
 kbg2020 (20 Feb 2020 : 14:32)
TriumphGuy   
Mon Feb 24 2020, 01:42am
Member No: #47272
Joined: Jan 13 2017
Location: Halifax, West Yorkshire
We got it recovered to Andrew's sister's home. I checked the OBD2 socket for lives and grounds with my power probe and they're all fine. There is power to the CAN high and CAN Low pins. I tried my laptop again and it still isn't communicating. I tried it on my own C4GP and it picked up the VIN so my Diagbox is definitely working. The next thing to do is to trace the wires from the OBD2 socket but that will have to wait until the weather improves.
TriumphGuy   
Tue Feb 25 2020, 03:04pm
Member No: #47272
Joined: Jan 13 2017
Location: Halifax, West Yorkshire
I've just found this video on YouTube:
- Click Here -
It has given me some more pointers on how to check the CAN high & CAN low pins on the OBD2 connector. I might do some measurements on my own C4GP for a reference on a known working socket.
1 User said Thank You to TriumphGuy for this Post :
 kbg2020 (07 Mar 2020 : 09:47)
TriumphGuy   
Thu Feb 27 2020, 01:33am
Member No: #47272
Joined: Jan 13 2017
Location: Halifax, West Yorkshire
I've posted this question on the French Car Forum and the Citroen Picasso Club forum and somebody suggested using a cheap code reader so I've ordered one on Amazon. I'll try it on my C4GP as I still get fault codes for the air suspension (I know that they will keep on coming back if I clear them) and a cheap code reader is less hassle than using Diagbox on the laptop. Something I've noticed with the version of Daigbox that I have installed is that it resets the time and date when it scans all the modules which is a bit of a pain. I'll take some measurements on the pins on the OBD2 socket as a reference. The only thing I'm loath to do is the resistance between the CAN high and CAN low pins. It should be 60 Ohms and it MUST be done with the battery disconnected and I'm a bit loath to disconnect my battery.
1 User said Thank You to TriumphGuy for this Post :
 kbg2020 (07 Mar 2020 : 09:47)
BigJohnD   
Thu Feb 27 2020, 05:52am

Member No: #82
Joined: Jan 22 2007
Location: Hoylake
The worst that's likely to happen from disconnecting the battery is the clock may need re-setting and the digital speedo default to Km/h.
1 User said Thank You to BigJohnD for this Post :
 kbg2020 (07 Mar 2020 : 09:47)
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