Citroen C4 canbus comms

[hezekiel]

Hi,

I've a C4 Picasso 1.6 HDi BMP 2008. Every time I power it up it displays "HANDBRAKE FAULTY" and after a while "ESP / ASR FAULTY". The failure mode I have is the least of 3 possible, and it is described in a manufacturer's document. Basically everything works except automatic engagement of handbrake and hill holder. I could live with it but the warning chime and failure messages flashing on the display is a no-no considering MOT or trading the car.

The only fault code that the ESP has is "ESP8.1 No communications with the engine management ECU Data invalid - Temporary - U1208".

The fault can be erased and it stays away even if the power is cycled. It always shows up again at every engine startup. I tried charging the battery and having the charger hooked up to assist keeping the voltage but it made no difference. I have reset the BSI several times to no avail.

I also removed all the power distribution box, BSI and ABS pump/valve unit connectors. Everything was fine, no oxidation. I measured the canbus line resistance across the pins at ESP unit, BSI and engine ECU. It was solid 120 ohms, and apparently the communications work most of the time since the fault is intermittent.

It is said that the system tolerates 500ms blackout in the comms before activating a trouble code. It could be due to low voltage during cranking, but hooking up the battery charger did not help. Anything else to do before I start swapping ESP units? Is it possible to update the controller software with Lexia?

[genius76]

sou if u read everything.......

C4 PICASSO - D6AX02QSP0 - Information: The error code U1208 (Computer system ABS / ESP) Pp. 1
= [object% 20Window] 25.10.2011 23:57:34
INFO: ERROR CODE U1208 (COMPUTER SYSTEMS ABS / ESP)
Computer ESP BOSCH8.1
Error Code U1208
Description DTC for
after-sales service
Error - no communication with the engine control computer: Damaged data
Description Diagnostic Possibility 1: The time code transmission fault is 500 milliseconds
Data from the sensor clutch pedal, the engine control unit are sent do not match
data coming from the computer ESP
Possibility 2: The time code transmission fault is 500 milliseconds
Fault blocks of data transmitted ECU
Possibility 3: The time code transmission fault is 500 milliseconds
Error sensor values ***8203;***8203;pedal sent the engine control unit
Activation conditions diagnostics Ignition on
Terms disappearance DTC Option 1: Data from the sensor clutch pedal, the engine control unit sent without
correspond to the data from the PC ESP
Possibility 2: True blocks of data from the engine control unit
Possibility 3: True value of the sensor accelerator sent by the control unit
engine
Alarm conditions when a fault Possibility 1: Antilock Braking System (ABS) will go into emergency mode
Immediate termination of all control function (Dynamic Stability (ESP))
Option 2: Anti-lock brakes (ABS) will go into emergency mode
Immediate termination of all control function (Dynamic Stability (ESP))
Help function in starting on a slope off
Transition with the electric parking brake in manual mode
Possibility 3: The control functions remain active
Help function in starting on a slope off
Transition with the electric parking brake in manual mode
The illumination and display
warning messages
Possibility 1: -
Possibility 2: The MIL ESP / ASR
Possibility 3: The MIL ESP / ASR
Alarm off automatic features with electric brake
SERVICE warning lamp
Main possible customer complaints illumination of ABS and ESP
Suspicious areas Electrical connectors
CAN line
ESP control unit

[mage]

Ecu no DTC?

I have also had U1208 (C4 2006) inside ABS.
Ecu had DTC EGR (P0405).
When I solved EGR problem, U1208 (inside ABS) solved to.

U1208 Engine asks to put ABS light on.

[nutloose]

CAN wiring for ECU goes through the ABS controller.
If the EPB is similar to ones I have seen there is a "private" CAN bus from ABS to EPB

read live data from EPB during cranking to look for loss of comms?


If the ABS is the only controller recording the CAN comms failure try monitoring the voltage during cranking to ABS and ECU with dual trace scope. Do CAN wiring too if you have quad trace.
You could link the +12v ign wiring to both units so they must be powered at the same time to reduce the chance of 500ms break.

[diga1]

Ecu no DTC?

I have also had U1208 (C4 2006) inside ABS.
Ecu had DTC EGR (P0405).
When I solved EGR problem, U1208 (inside ABS) solved to.

U1208 Engine asks to put ABS light on.

a vhile ago i had same problem vith p407 and vas egr viring problem and confused can data from abs

[mage]

Customer came to his garage with complaint "litle bit black smoke, only in the morning"
No MIL on.
Garage read DTC P0405 from ECU
So Garage put on a new original EGR.
Now garage had big problem because again P0405 and now car also had MIL on??
Garage took car to a dealer.
Dealer put on again a new EGR, but again P0405 and MIL.
Dealer give Car an software update.
Now Dealer had bigger problem because DTC P0405, MIL on and now also on ESP light on (U1208)
After that Dealer put on a brand new ECU but still DTC P0405, MIL on and ESP light on (U1208

They measured Canbus communication for weeksss

Car came to me, to find this "unsolvable" problem.
On Google I see also many times U1208 inside ESP when engine had problem (FAB,EGR or other DTCs)
So I go first for engine problem (and not for ESP problem)
I found high resistance on pin 5 inside EGR connector
(not oxidation! but low contact pressure)
Fixed contact pressure pin5. Problem solved
I didn't even had to erase DTC from ESP (it was gone??).

I learned from this case that cars can respond different after software update

[hezekiel]

That's pretty amazing, guys! As a matter of fact, the car has 3 permanent fault codes relating to the EGR (will have to check tomorrow exactly what they were). I have tried 2 different EGR valves so far. I'll have a look into this soon!

[genius76]

looks same as heaved Toyota avensis
not working abs tr. control - fault code on catalysis get big spanner hard bum bum per o2 sensor solved code cleared
fast enjoy

[genius76]

That's pretty amazing, guys! As a matter of fact, the car has 3 permanent fault codes relating to the EGR (will have to check tomorrow exactly what they were). I have tried 2 different EGR valves so far. I'll have a look into this soon!

post here codes more like maf blaming egr or some rubbish

[hezekiel]

OK, here goes:

EDC16C34_DV6
fault codes present
Electric EGR valve position copy signal Valve opening too small
8WP - P0490
Electric EGR valve position copy signal Valve stuck open while driving
8WS - P1459
Electric EGR valve position copy signal Valve stuck during programming
8WK - P0409
Cooling Function Integrated into the ECU (fan unit) Open circuit or temperature too high
4IK - P0483

Two different EGR valves tested, so the fault may be somewhere else....

[genius76]

OK, here goes:


Cooling Function Integrated into the ECU (fan unit) Open circuit or temperature too high
4IK - P0483

Two different EGR valves tested, so the fault may be somewhere else....

some of engine items working tu hard and shortish amperes that ecu gets hot hot hot

check al live data first
turbo
rail pressure and bla bla
idling and 3500rpm cont. 3sec. minimum
if u not sure post here results

[mage]

All DTCs EGR refer to "copy signal Valve"
Look with software at data Position EGR
Problem with "wire backfeed EGR position?"
Or bad contact on that pin?


P0483 havend had this code before, but you can check
wiring and risistor in front of radiator.
Thats a common problem.

[hezekiel]

OK, a little update:

I checked connectivity between EGR valve connector and ECU. Every 5 wires were OK. I put in a brand new feshly charged battery + reset BSI. Nothing changed!
ESP canbus fault U1208 and those same engine DTC's are there.

I was not successful in downloading the engine software with my cheap Galletto copy, so can't do anything to it at the moment.

[pedro222]

Hello!
I have a same problem.
Did you fix the problem?
What was it?
Thanks!

[maki]

Same problem in my one C4..any know how solve it...EGR,ESP/ASR,Handbrake faulty???