c4 abs communicatin

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ian john
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c4 abs communicatin

Post by ian john »

Hi everyone, just joined and hope someone can help me keep sane
My wife has a 2011 c4 HDI sensotronic .driving home a month ago vehicle display said gearbox fault,abs esp fault engine fault so I'm a mechanic by trade and have 2 diagnostic tools . launch euro tab and a snap on modis both came up with communication to all modules except ABS= no communication
have checked the following all fuses inside and under bonnet , untaped the loom by bulkhead/battery looking for corroded wiring ,no damp in under bonnet fuse box
removed BSI and opened up all clean etc .
checked canbus resistance =60 ohms and 120 if I unplug ABS so assuming canbus terminates there . 2 main power and 2 earth to ABS ok also all other wires show continuity
my modis has a 2 channel scope and checked waveform of canbus at ABS and diagnostic port, can high and low mirror image each other assume ok .so I bit the bullet and sent ABS module off with a report for test they reported faulty and sent- back tested and repaired, so i put back together and pretty much the same still no communication with scanners . after pulling most of the car apart I am convined that its got to be the ABS so sent it back , they said they found another fault and repaired under warranty this time I didn't plumb it all in and just plugged in ,still the same .HELP can anyone tell me if communication to ABS goes through another path or what am I missing . all the fault codes are ones I cant seem to get correct info on and they are permanent in BSI as follows
U1F00
U1802
B162C
B1418
U1F48 [this one will cancel ]
P0500 is in engine ECU and is speed sensor related
U1313 electric hand brake
regards
Ian

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GiveMeABreak
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Re: c4 abs communicatin

Post by GiveMeABreak »

Hi Ian

These EGS systems are horrible and we have no end of members with issues with these things, but let's see if I can get you some help with the codes. First off, thanks for the Forum donation.


Next, please pop your VIN up and it will be automatically masked on post submission. I'll need that to ensure the codes are related to the correct system as fitted to your vehicle.

wheeler
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Re: c4 abs communicatin

Post by wheeler »

It sounds like you have done the proper checks & would say going on the checks you have done I would have come to the same conclusion as you.
The only one thing you have not said is if there is an ignition switched live at the ABS unit? There normally would be, i’d need to look at a wiring diagram to confirm if it has one & which pin it is.
Im not totally convinced by some of these ECU repair companies. I have had ECU’s been sent back with ‘no fault found’ & they ended up being faulty ECU’s.
If you send me your reg or last 8 digits of your VIN i can have a look at a wiring diagram & those fault codes for you.

ian john
Donor 2021
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Joined: 05 Apr 2021, 17:05

Re: c4 abs communicatin

Post by ian john »

Hi Marc and wheeler thanks for help
Marc the vin No is VF7**************[VIN obfuscated, can be read by forum staff] and answer to wheeler,s question
Yes I have a ignition live at pin 35 ( purple wire )
Regards
Ian

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GiveMeABreak
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Re: c4 abs communicatin

Post by GiveMeABreak »

So you have a C4 (B7) 5 DOOR SALOON 1.6 HDI 115 (DV6C) with piloted manual gearbox 6 (With stop and start)

I can only pull some of those codes as there are 2 digits missing from the end of some of them.

B1418 00: Fault in the status of the seat belt fastening information for determining the presence of the driver
U1F00 00: Fault event not stored in the faults log

U1802 (Digits Missing)
B162C (Digits missing) Possible Fault: Accessories positive relay control and status not coherent.
P0500: Intersystems CAN: Speed information incorrect or absent (Information not received or received invalid by the engine management ECU on the CAN)
U1313 Fault - absence of communication with the stability control (ESP) ECU: No signal

A lot of these relate to the BSI or the intersystems CAN.

ian john
Donor 2021
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Re: c4 abs communicatin

Post by ian john »

Hi Marc , yes the descriptions on my launch said the same , what I can’t make out is why I can’t communicate with the ABS module , would the BSI stop communication, and how ? If the can system checks out ok and I can communicate with all the other modules , but am I correct in saying P0500 suggests can faults ?
Regards
Ian

ian john
Donor 2021
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Re: c4 abs communicatin

Post by ian john »

Hi all , is it possible to supply a wiring diagram for this dreaded nightmare please
Ian

wheeler
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Re: c4 abs communicatin

Post by wheeler »

I dont have the full details so this is for a model without ESP
Attachments
C4 ABS.jpg

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GiveMeABreak
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Re: c4 abs communicatin

Post by GiveMeABreak »

I'll sort the correct one for the specific vehicle Wheeler with ESP:

Image

ian john
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Re: c4 abs communicatin

Post by ian john »

Hi guys thanks , Marc would the components and wiring list be the same as you
Supplied for Mrtattoo .?
Ian

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GiveMeABreak
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Re: c4 abs communicatin

Post by GiveMeABreak »

Yes where the numbers are the same.

The components can be found on the wiki in ascending order in sections here:

https://frenchcarforum.co.uk/wiki/Elect ... ring_Codes

Here's the main ones for you:

CA00 : ignition switch /
0004 : instrument panel /
1032 : electrical supplies protection and management unit
7801 : ESP cut-off switch
7804 : ESP accelerometer gyroscope
PSF1 : engine compartment fusebox panel
BSI1 : BSI

7810 : front LH ESP sensor
7815 : front RH ESP sensor
7820 : rear LH ESP sensor
7825 : rear RH ESP sensor

ian john
Donor 2021
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Re: c4 abs communicatin

Post by ian john »

Thanks 👍