Citroen DS4 Stop start/LIN fault

This is the Forum for all your Citroen Technical Questions, Problems or Advice.

Moderator: RichardW

Post Reply
johnny1901
Posts: 14
Joined: 01 Jul 2022, 22:12
Location: Preston
My Cars: 2015 Citroen DS4

Citroen DS4 Stop start/LIN fault

Post by johnny1901 »

Hello, my first post on this site.

I have a 2015 Citroen DS4 HDi 115 with stop start. Since buying the car around 6 months ago the stop start has never worked. However, in recent weeks, usually when i am braking, I get the "Engine fault, get repair" (or similar) message and alarm sound come on. The car drives perfectly but I keep getting this warning and the ECO sysem light flashes on the button to the right of the driver.

I had read that a low battery can cause stop start to malfunction and also cause error codes. I have just replaced my battery (previous one was dated March 2015!), with an AGM 097 and it gives 13.00 volts with engine off. However, stop start still does not work and everything I described above still happens.

Fault codes from Lexia as follows:

P1536. Intermittent. Measurement of brake pedal position . Incoherence between the two brake pedal sensors detected under deceleration.
P1382. Intermittent. Ancilliary drive belt. Fault in coherence between engine speed and altenator speed
U1133. Intermittent. Communication fault on LIN. The reversible alternator is confirmed absent.
U1134. Intermittent. Communication fault on LIN. No communication with the voltage retaining device.
U1400. Intermittent. Alternator LIN network. Registering of a fault ton the LIN network
U1333. Intermittent. Reversible alternator. Voltage retaining Device.

I have checked all plugs. I have also scoped the alternator and there is a good LIN signal with alternator unplugged and with alternator plugged in (some videos show LIN signal disappearing when alternator is connected indicating a dud alternator, however, I do not see this). I have no idea how to test the alternator. Although I get a good LIN signal when I backprobe the alternator, there could be a break in the alternator connection so I am only seeing the LIN network as if the alternator is unplugged. Assuming that is not the case. then the LIN network seems fine: A good square wave with many send and response signals.

So I have a brand new fully charged battery. Stop start does not work. ECO light flashes and I get Engine Fault message and alarm continuously when I drive.

Any ideas on how I further try to diagnose the problem without becoming a "parts swapper". The Alternator and Voltage Retaining Device are very expensive parts.

Cheers, John
RichardW
Forum Treasurer
Posts: 10814
Joined: 07 Aug 2002, 17:12
Location: United Kingdom
My Cars: MK2 '17 C4GP 1.6 BlueHDi 120
'13 3008 1.6 HDi GripControl
x 984

Re: Citroen DS4 Stop start/LIN fault

Post by RichardW »

Since it occurs on breaking and you have a fault with the brake pedal switch, then I would start there. Can you see it in Diagbox, and check that both signals are chaing state at the same time? If not, it's cheap enough I expect to play parts darts and see if a replacement fixes it. If the SS still doesn't work, then I wouldn't worry if you don't get error messages - the fuel saved vs the cost of wearing out a very expensive alternator does't make financial sense!!
Richard W
User avatar
GiveMeABreak
Forum Admin Team
Posts: 37014
Joined: 15 Sep 2015, 19:38
Location: West Wales
My Cars: C3 Aircross SUV HDi Flair Peperoncino Red (The Chili Hornet)
C5 X7 2.0 HDi Exclusive Mativoire Beige (The Golden Hornet)
C3 1.6 HDi Exclusive Aluminium Grey (The Silver Hornet)
C5 MK II 2.0 HDi Exclusive Obsidian Black
C5 MK I 2.0 HDi SX Wicked Red
Xantia S2 2.0 HDi SX Hermes Red
C15 Romahome White
XM 2.0 Turbo Prestige Emerald Green Pearlescent
XM 2.0 Turbo Prestige Polar White
XM 2.0 SX Polar White
CX 20 Polar White
GS 1220 Geranium Red
CX 2.4 Prestige C-Matic Nevada Beige
GS 1000 Cedreat Yellow
x 5648

Re: Citroen DS4 Stop start/LIN fault

Post by GiveMeABreak »

The flashing of the ECO button means the Stop Start function is not working for the current situation and is perfectly normal. If you look at the reasons why, you will see that a problem with the braking system is one reason why it will not engage which I have highlighted:

STOP mode is not invoked when:
  • the vehicle is on a steep slope (up or down),
  • the driver's door is open,
  • the driver's seat belt is not fastened,
  • the vehicle has not exceeded 6 mph (10 km/h) since the last engine start (using the key or the "START/STOP" button),
  • the electric parking brake is applied or being applied,
  • the engine is needed to maintain a comfortable temperature in the passenger compartment,
  • demisting is active,
  • some special conditions (battery charge, engine temperature, braking assistance, ambient temperature...) where the engine is needed to assure control of a system.
So I would focus on getting the braking issue sorted first as Richard has suggested and then deal with the other faults if they remain.
Please Don't PM Me For Technical Help

Marc
johnny1901
Posts: 14
Joined: 01 Jul 2022, 22:12
Location: Preston
My Cars: 2015 Citroen DS4

Re: Citroen DS4 Stop start/LIN fault

Post by johnny1901 »

Thanks for the comments. I did test the brake switch functionality in Diagbox and it seemed fine, both sides switching as they should. Also, the 12v signal appeard/disappeared on the alternator 5 pin plug when the brake pedal was depressed. HOWEVER, I took the brake light switch off yesterday and only one side is switching when I tested with a multimeter. So a new switch has been ordered. I hope that cures the issue...lets see.
User avatar
GiveMeABreak
Forum Admin Team
Posts: 37014
Joined: 15 Sep 2015, 19:38
Location: West Wales
My Cars: C3 Aircross SUV HDi Flair Peperoncino Red (The Chili Hornet)
C5 X7 2.0 HDi Exclusive Mativoire Beige (The Golden Hornet)
C3 1.6 HDi Exclusive Aluminium Grey (The Silver Hornet)
C5 MK II 2.0 HDi Exclusive Obsidian Black
C5 MK I 2.0 HDi SX Wicked Red
Xantia S2 2.0 HDi SX Hermes Red
C15 Romahome White
XM 2.0 Turbo Prestige Emerald Green Pearlescent
XM 2.0 Turbo Prestige Polar White
XM 2.0 SX Polar White
CX 20 Polar White
GS 1220 Geranium Red
CX 2.4 Prestige C-Matic Nevada Beige
GS 1000 Cedreat Yellow
x 5648

Re: Citroen DS4 Stop start/LIN fault

Post by GiveMeABreak »

Just make sure you get a decent branded replacement (preferably an original OEM one) and the correct part.
Please Don't PM Me For Technical Help

Marc
johnny1901
Posts: 14
Joined: 01 Jul 2022, 22:12
Location: Preston
My Cars: 2015 Citroen DS4

Re: Citroen DS4 Stop start/LIN fault

Post by johnny1901 »

Ive ordered an OEM part, 9804869480....code taken from the switch fitted to my car.
User avatar
GiveMeABreak
Forum Admin Team
Posts: 37014
Joined: 15 Sep 2015, 19:38
Location: West Wales
My Cars: C3 Aircross SUV HDi Flair Peperoncino Red (The Chili Hornet)
C5 X7 2.0 HDi Exclusive Mativoire Beige (The Golden Hornet)
C3 1.6 HDi Exclusive Aluminium Grey (The Silver Hornet)
C5 MK II 2.0 HDi Exclusive Obsidian Black
C5 MK I 2.0 HDi SX Wicked Red
Xantia S2 2.0 HDi SX Hermes Red
C15 Romahome White
XM 2.0 Turbo Prestige Emerald Green Pearlescent
XM 2.0 Turbo Prestige Polar White
XM 2.0 SX Polar White
CX 20 Polar White
GS 1220 Geranium Red
CX 2.4 Prestige C-Matic Nevada Beige
GS 1000 Cedreat Yellow
x 5648

Re: Citroen DS4 Stop start/LIN fault

Post by GiveMeABreak »

👍
Please Don't PM Me For Technical Help

Marc
johnny1901
Posts: 14
Joined: 01 Jul 2022, 22:12
Location: Preston
My Cars: 2015 Citroen DS4

Re: Citroen DS4 Stop start/LIN fault

Post by johnny1901 »

Well new OEM brake pedal switch fitted. Problem still persists. When I brake (or maybe it is the fact thet the car is slowing down as the stop/start is speed sensitive) I get the "engine fault, seek repair " message and warning sound. Again, car drives perfectly and engine is fine but stop start is disabled. Exactly same codes as in my first post are listed in the engine ECU. As said previously I have scoped the LIN bus and it seems fine. Yet the codes indicate both alternator and voltage retaining device are not recognised on LIN. Also the P1536 code seems to indicate a problem with the brake switch, but all voltages are fine and the switch is brand new and works as intended...they only witch a 12v signal. For the moment I am stumped. I have service box/sedre and cann get wiring diagrams but I dont see any LIN specific diagrams covering the stop/start system. If I remember correctly LIN is pin 4 on the alternator 5 pin plug. Waveform was fine.
RichardW
Forum Treasurer
Posts: 10814
Joined: 07 Aug 2002, 17:12
Location: United Kingdom
My Cars: MK2 '17 C4GP 1.6 BlueHDi 120
'13 3008 1.6 HDi GripControl
x 984

Re: Citroen DS4 Stop start/LIN fault

Post by RichardW »

Does it come on every time you brake? Did the switch look original - might it have been replaced before incorrectly? Usually the link with the brake pedal is to restart the engine when you let go off the brake ready to move off, so not sure why you are getting an error when you apply the brakes. Does it always set all those codes?
Richard W
User avatar
GiveMeABreak
Forum Admin Team
Posts: 37014
Joined: 15 Sep 2015, 19:38
Location: West Wales
My Cars: C3 Aircross SUV HDi Flair Peperoncino Red (The Chili Hornet)
C5 X7 2.0 HDi Exclusive Mativoire Beige (The Golden Hornet)
C3 1.6 HDi Exclusive Aluminium Grey (The Silver Hornet)
C5 MK II 2.0 HDi Exclusive Obsidian Black
C5 MK I 2.0 HDi SX Wicked Red
Xantia S2 2.0 HDi SX Hermes Red
C15 Romahome White
XM 2.0 Turbo Prestige Emerald Green Pearlescent
XM 2.0 Turbo Prestige Polar White
XM 2.0 SX Polar White
CX 20 Polar White
GS 1220 Geranium Red
CX 2.4 Prestige C-Matic Nevada Beige
GS 1000 Cedreat Yellow
x 5648

Re: Citroen DS4 Stop start/LIN fault

Post by GiveMeABreak »

Aren't we talking about a manual here? It should restart when the clutch is engaged, not when the brake is released - as far as I'm aware that's only on an auto? I know mine gives me a message when I don't press the clutch pedal down far enough.

Can you pop your VIN up so I can see what exactly you have?
Please Don't PM Me For Technical Help

Marc
johnny1901
Posts: 14
Joined: 01 Jul 2022, 22:12
Location: Preston
My Cars: 2015 Citroen DS4

Re: Citroen DS4 Stop start/LIN fault

Post by johnny1901 »

It's a six speed manual. VIN VF7**************[VIN obfuscated, can be read by forum staff]. The "engine fault" light and buzzer only come on when I brake i.e. slow down. It never comes on just cruising along. The same fault codes are present as in opening post, and are posted within minutes of me clearing them from engine ECU. Engine runs absolutely fine, no limp mode, it is perfect...just get the waning light and buzzer constantly sounding when I brake/slow down, and ECO mode is not active. I found this worksheet: which covers the stop start system and all wire references are exactly as on my car. I will work through to make sure all cables have continuity and all connectors are clean.
RichardW
Forum Treasurer
Posts: 10814
Joined: 07 Aug 2002, 17:12
Location: United Kingdom
My Cars: MK2 '17 C4GP 1.6 BlueHDi 120
'13 3008 1.6 HDi GripControl
x 984

Re: Citroen DS4 Stop start/LIN fault

Post by RichardW »

Possibly Marc, can't remember, it's so long since ours worked :rofl2:
Richard W
User avatar
GiveMeABreak
Forum Admin Team
Posts: 37014
Joined: 15 Sep 2015, 19:38
Location: West Wales
My Cars: C3 Aircross SUV HDi Flair Peperoncino Red (The Chili Hornet)
C5 X7 2.0 HDi Exclusive Mativoire Beige (The Golden Hornet)
C3 1.6 HDi Exclusive Aluminium Grey (The Silver Hornet)
C5 MK II 2.0 HDi Exclusive Obsidian Black
C5 MK I 2.0 HDi SX Wicked Red
Xantia S2 2.0 HDi SX Hermes Red
C15 Romahome White
XM 2.0 Turbo Prestige Emerald Green Pearlescent
XM 2.0 Turbo Prestige Polar White
XM 2.0 SX Polar White
CX 20 Polar White
GS 1220 Geranium Red
CX 2.4 Prestige C-Matic Nevada Beige
GS 1000 Cedreat Yellow
x 5648

Re: Citroen DS4 Stop start/LIN fault

Post by GiveMeABreak »

That info you posted is not the same as the official procedure.

Officially you check for one or more fault codes and proceed depending on which faults are active. There is no Stop Start ECU but there is a device called the converter unit or the central voltage maintaining device. The only parts to be replaced are either the central voltage maintaining device or the reversible alternator.

If you are only getting U1134, then you only need to carry out the first check - but not with the other codes.
If you are getting U1133, U1134 and U1400 without other fault codes, then you disconnect the black 5-track connector from the reversible alternator.

If fault code U1134 has disappeared, then the reversible alternator has to be replaced. If U1134 reappears then you go back and check the connections and also the state of the connectors for faulty, bent or missing.
Please Don't PM Me For Technical Help

Marc
johnny1901
Posts: 14
Joined: 01 Jul 2022, 22:12
Location: Preston
My Cars: 2015 Citroen DS4

Re: Citroen DS4 Stop start/LIN fault

Post by johnny1901 »

Thanks Marc. I get 6 codes, including the P1536, so I'm still unsure what to do.

I think my alternator has gone. I watched this Youtiube video: and my car has exactly the same issue with the brake switch. Pin 3 on the alternator has 12v when brake predal is in rest position and 4.0v when it is pressed. Same voltages are seen on brake switch. Unplugging alternator and testing brake switch shows voltage going to zero when brake pedal is pressed. There is nothing on the wiring diagrams to say what the correct low voltage on pin 3 on the alternator and associated wiring should be...but I assume it is zero. Unplugging the alternator gives this. Ironically Diagbox showed both switches switching correctly....but it definitiely only switches from 12 to 4v. This would explain the issue every time I brake, if the ECU isn't seeing zero volts but 4v. I messaged the guy in the video to make sure it solved the issue. I'll also test al the wiring as per the sheet in my last post. My bet is the alternator has gone. Recon reversible alternators are £330...unless someone knows a cheaper source!
johnny1901
Posts: 14
Joined: 01 Jul 2022, 22:12
Location: Preston
My Cars: 2015 Citroen DS4

Re: Citroen DS4 Stop start/LIN fault

Post by johnny1901 »

Just a quick update. Having got all the codes in the first post, and constant "engine fault - repair needed", whenever I braked, and no stop-start function, I decided to replace the alternator (having already replaced the brake switch). As in the video above, this solved the problem and the car is error code free and running perfectly with stop-start. As in the video above I found pin 3 of the alternator 5 pin plug would only switch from 12v to around 5v when the brake was pressesd. Disconnecting the 5 pin plug saw the voltage switch from 12v to 0V (as it should). This explains why I got the fault when the brake was pressed, as the stop start system uses the on/off status of the brake secondary switch. Main lesson: Dont buy a used alternator...I wasted £80 on a dud unit which I was promised worked. Finally got one for £445 from carparts4less. Ouch! While I was at it, fitted new timing belt, water pump, tensioners and auxiliary belt...and flushed cooling system. That should now last life of the car.
Post Reply