Fault U1208

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Mikes
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Fault U1208

Post by Mikes »

Good morning,
I have a citroen 2007 c4 picasso grand. After 1 year I got it, a fault U1208 appeared.
And after 4 days it appeared faulty handbrake, esp and service.
The first thing I checked was the battery and it's ok.
I went to the garage with a maxisys diagnostic tool where he tried to delete the fault but it came up again.We checked the four sensors on the wheels and its working. We checked the 'plugs' of the abs, ECU under the Bonnet (not the handbreak one). Everything looks fine. The handbreak is working. But the fault is still up.
Any ideas regarding that? Any help would be great. Thanks
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Re: Fault U1208

Post by GiveMeABreak »

Hi and welcome.

That fault code means there is no communication between the ESP ECU and the Engine Management ECU.

Whilst active, all the ESP functions are deactivated including Hill Start Assist etc. Basically it is not detecting any information being sent by the engine ECU. The SERVICE warning lamp will be lit, as will the ESP / ASR lamp.

The suspect areas are: Connectors, CAN network, ESP ECU. So first thing is to check the actual wiring connectors. Has any work been done recently on the vehicle?
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Re: Fault U1208

Post by Mikes »

Hi Marc,
No there hasn't been done any work at the vehicle at the moment.
Can you please give me a bit more explanation regarding the wiring connectors?
Thanks
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Re: Fault U1208

Post by GiveMeABreak »

Just eliminate the obvious - the vehicle ECUs talk to each other via various multiplexed data networks. Somewhere along the line there is a communication disruption - so it would seem the first and easiest places to check are the physical connections on the ESP ECU and the Engine ECU.

It's also not unknown on the C4 Picassos for the wiring to break in the looms (they have far too many wires in a thick bundle that puts stress on the wiring and can cause breaks and shorts), but that requires fault finding.

If you post up your VIN (automatically masked from public view) I can dig out a wiring diagram for your specific C4P. I can point you in the right direction for likely connections to check.
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Re: Fault U1208

Post by Mikes »

Thanks so much.
The Vin is VF7**************[VIN obfuscated, can be read by forum staff]
Last edited by GiveMeABreak on 10 Feb 2020, 11:46, edited 1 time in total.
Reason: Corrected VIN
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Re: Fault U1208

Post by GiveMeABreak »

Ok, so here is the Injection ECU wiring as it shows the main CAN connections to the ESP ECU and from the ESP ECU to the BSI.

Additional hardware codes can be fouind here in ascending order on our Wiki:

PSA Electrical Codes

1320 is the injection ECU
7800 is the ESP ECU

CAN Wiring Injection ECU:
9010 : High Intersystem 2 Can bus
9011 : Low Intersystem 2 Can bus

CAN Wiring ESP to BSI:
9000 : High Intersystem / Can bus
9001 : Low Intersystem / Can bus

Injection Wiring C4 Picasso 110 FAP DV6TED4)

Image

Location

Image
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Re: Fault U1208

Post by Mikes »

Thank you very much for your help! I really appreciate it.
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Re: Fault U1208

Post by Mikes »

Can you on some way send me these pictures in a file? So that I can download and print them?
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Re: Fault U1208

Post by GiveMeABreak »

Unfortunately not. These are SVG (vector graphics), so will scale perfectly to any size. This enables people with mobiles, or PCs to be able to view them and zoom them up without losing definition. However most browsers can display SVG files - so if you right click the image you want, then choose 'save image as', then save to your PC, you should then be able to double click the image and select your browser to view it. You can then print it from your browser.
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Re: Fault U1208

Post by Mikes »

Yes you are right. I was trying to do it with my mobile that's why I couldn't print it. I used the pc and ot is printed out perfectly. Thanks again.
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Re: Fault U1208

Post by RichardW »

Re-scan it and see if there are any EGR faults. These don't necessarily put the engine management light on, but can cause the brake warning to come on. Been there, chased it for 9 months....
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Re: Fault U1208

Post by klim »

Hi,
Citroen C4 Picasso 1.6 HDi mcp 2007 VIN VF7**************[VIN obfuscated, can be read by forum staff]. The car was recently started on Wednesday, without any problems my wife went and came back from work. Today, after turning the key, a Christmas tree appeared with errors in the handbrake, ABS ESP, gearbox and Engine system management. The car starts, the engine works well, but there is no reaction to the gas pedal and it does not change position from N (it changes correctly only on the ignition). Handbrake works despite errors. After connecting to the diagbox, a few errors appeared (attached in the photos). There is no communication with the ABS ECU. I can't connect to it at all via diagbox, I'm getting a connection error message.
bledy.jpg
bled1.jpg
What did I do while reading the forum posts:
- I checked the BF07 wire with the multimeter - there is a connection between the fuse (PFS1) and ESP (7800)
- I checked the CAN 9000 and 9001 cable between ESP 7800 and BSI1 - connected
- I also checked the CAN connection between ESP 7800 and 1320 ECU - connected.

What else should I check?
There is a lot of grease on the ECU ESP plug, is it normal?
smar.jpg
Should there be a connection between ESP pin 26 and BSI1 pin 4?
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Re: Fault U1208

Post by GiveMeABreak »

@KLIM: Leave it with me for a few minutes, I'm putting some info together for you on these fault codes.
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Marc
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Re: Fault U1208

Post by GiveMeABreak »

Here are the fault descriptors - have a careful read through. The first few relate to the accelerator pedal. These have 2 tracks of information inside the unit that are constantly compared with each other. When the data on one or more of the tacks in incoherent or does not make sense, then you'll get these faults. As this is linked to the engine ECU, of course you will be getting incorrect data so that can have a knock-on effect to the other systems.

So I would focus first on the accelerator as that can be the source of a lot of the issues.

Fault Code: P1645
Description of Fault: Accelerator pedal point of resistance information fault: Plausibility.
Conditions for Fault to clear: Ignition on
Downgrade Modes whilst Fault is active:
  • Deactivation speed limiter until the next time the ignition is switched on
  • The speed limiter is not in default
Symptoms: -
Suspect Areas: Accelerator pedal

Fault Code: P1728
Description of Fault: CAN communication: Lack of coherence of the engine torque information sent on the CAN. Engine torque information sent on the CAN not coherent.
Conditions for Fault to clear: Ignition on
Downgrade Modes whilst Fault is active:
  • Inhibiting of the programming of the accelerator pedal 0 % for the hill start assistance function.
  • Cutting of the driveability rebound function (driveability down-graded).
Symptoms: Lack of power
Suspect Areas: Accelerator pedal

Fault Code: P2137
Description of Fault: Accelerator pedal signal: Coherence between the 2 tracks of the accelerator pedal sensor. The difference between the accelerator pedal sensor track 1 and track 2 signals is greater than 6 % for 200 ms.
Conditions for Fault to clear: Driving for 5 minutes with frequent pressing of the accelerator pedal.
Downgrade Modes whilst Fault is active:
  • The engine ECU limits the fuel flow
  • Deactivation of the easy move 0 % pedal initialisation (Electrically controlled secondary brake)
  • Cut in the exhaust heat recovery function
  • Deactivation of the electrical faults of the accelerator pedal sensor
Symptoms: Lack of power
Suspect Areas:
  • Foot throttle pedal
  • Electrical harness
  • Connectors

Fault Code: U1208
Description of Fault: Fault in the information transmitted by the engine management ECU: Value received incorrect. No information sent by the engine ECU (Foot throttle pedal; Engine speed; engine torque).
The time of appearance of the fault code is 1s.

The following conditions have to be met for fault activation:
- Ignition on
- The starter motor is not operating
Technical precision on the context of appearance of the fault code
  • Supply voltage correct between 8V and 16V (Pin 3 of the 28-way connector)
  • Absence of fault codes U1000 - U1003 - U1108
Warning Lamps: If there is a fault on the information on accelerator pedal position or engine speed:
"SERVICE" warning lamp
Sport warning lamp
Snow warning lamp
Automatic or 6-speed piloted manual gearbox warning lamps (Orange PRND triangle)
Display of a "-" on the fascia panel
Conditions for Fault to clear: Reception of 20 consecutive items of valid information.
Downgrade Modes whilst Fault is active: Possibility 1
Engine speed fault
- Change to neutral and no gear can be engaged
- Opening of the clutch when close to idling speed
- Take-off deactivated (With the vehicle stopped)
- If the vehicle has the Stop and Start system : Stop and start function deactivated
Possibility 2
Accelerator pedal position fault
- Automatic mode deactivated
- Change to neutral and no gear can be engaged
- Opening of the clutch when close to idling speed
- Take-off deactivated (With the vehicle stopped)
Possibility 3
Fault with engine temperature and torques
- Gear engagement downgraded
- Crawling deactivated
Symptoms: Possibility 1
Engine speed fault
- Automatic mode deactivated
- Change to neutral and no gear can be engaged
- Take-off deactivated
- Difficult/impossible to change a gear
Possibility 2
Accelerator pedal position fault
- Automatic mode deactivated
- Change to neutral and no gear can be engaged
- Take-off deactivated
- Difficult/impossible to change a gear
Possibility 3
Fault with engine temperature and torques
- No customer complaint
Suspect Areas:
  • 28-way harness of the piloted manual gearbox ECU
  • Engine ECU
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Marc
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Re: Fault U1208

Post by klim »

Bingo!
I checked the accelerator pedal potentiometer and noticed signs of corrosion on the silicone cover.
272776527_306221478028058_4924485821724444126_n.jpg
273210456_633960777721822_3291478236025510148_n.jpg
There was a problem with water dripping down the cable. Everything seems to be secured, but probably a hole appeared over time. There wasn't much water. Literally single drops. Water also appears on the other side - on the battery and fuse box. The cause is probably blocked drains. Thank you very much for help!
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