2008 C5 exclusive

[mikal]

Recently the frog machine has started to throw a tantrum re the elec parking brake and all hell lets loose.
The brake is fine, so is the esp BUT if I slam the brakes on, especially when towing, the dash all lights up with the dredded SERVICE bongs and the esp light and badda bing out goes the cruise control.

Anyone know why?????????

[GiveMeABreak]

So can you confirm:

Does this happen only when towing?
My first thoughts are that it may be to do with the towbar electrics - these modern cars are designed to recognise certain towbar kits with an interface module that when connected and configured in the BSI, notifies the ESP programme, which then uses a special programme to account for towing - and this adapts the system, especially under harsh or emergency braking.

The ESP system is also the master controller of the electronic parking brake, so no coincidence there.

Do you have a Lexia to check for specific errors? This would throw some more light about what it is not happy with.
Secondly, is the towbar electric kit compatible with the car?
Next, has this just started happening - or is it only when you have jammed the brakes on that you have noticed it?

[mikal]

Its happens when towing AND reg driving, after the cars warmed up and I slam on the brakes. Never happened before when towing/driving, its just started.
The SERVICE light comes on with "handbrake fault" and the esp and abs lights. Its a major PITA as I am 1/3rd of the way to Greece n back. If I drive real carefull I can use the cc for a 100 miles or so but I know any minute. It''go.
Am in Greece now.

AS b4 car was fine b4

[GiveMeABreak]

Ok, so a diagnosis is really important - there are over a 100 electronic handbrake fault codes and of course it may be the ESP system - so getting it on Diagbox is essential to find out what is going on.

Any fault in the engine ECU or the ESP / ABS system and you will loose Cruise Control as it is deactivated for safety reasons. So we have to determine which of the 3 systems is causing the error and causing the knock-on faults.

[mikal]

Guess I'm going to suffer for the next 2 months till we get the frog machine back home! Bugger.

[mikal]

Am now back from our epic trip and the problem is still there. (Now that I am not towing). It seems that I have to let the car idle for a while after starting. It doesn't want to be put into D or R str8 after starting. If I do the bing bing the hand brake warning comes on with the SERVICE and esp warning lights....(which we all know and love).
Could it be that the electric handbrake system is just "not online" str8 after starting?

Will a check up with a Lexia find a fault??

If so, who has one near me in East Cornwall?

[GiveMeABreak]

Glad you're back ok.

Yes, as I said there should be a code stored - although some intermittent faults will disappear after certain conditions are met, so it is important to try and get it to replicate the error message when connected to Lexia if the fault has not already been stored.

As I mentioned there are over 100 of these fault codes relating to the Electronic Handbrake on the X7 and the ESP controls the activation of the system. It will also be linked to the Auto box too within the system, so getting a few pointers is really important. Once you have the codes, it will help with some indicators.


Have a look at the Lexia members here:
viewtopic.php?f=19&t=56452

Right at the bottom there is a link to the map - as you can see, member 'Spiff' is in Cornwall, so may be able to help.

[JohnD]

Any fault in the engine ECU or the ESP / ABS system and you will loose Cruise Control as it is deactivated for safety reasons.

When I'm towing my caravan using cruise control, even if I just get on a stretch of rough surface, the cruise deactivates.

[GiveMeABreak]

John, do you have an OEM electrics or dedicated C5 X7 solution for towing with the trailer?

Only dedicated model - specific solutions are guaranteed to work with the vehicle's electronic systems to adapt to a trailer, for example (and model dependent):

• ESP / ABS Programme Adaptation for towing
• Cruise adaptation (likely to gradually increase acceleration to set speed, rather than engaging warp speed when towing)
• CAN compliant connection
• Auto shut off or rear parking sensors
• Deactivation of Car Fogs when Towing
• Rapid Flashing of indicators for a trailer bulb out

They do tend to cost £150 - £200 for a decent kit, but are probably worth the investment.

The specific harness goes into the BSU here, and is activated with Lexia.

Non dedicated units won't interface with the vehicle - specific systems.

[EDC5]

Is that module the BSR? as in the towing module that is detected when using diagbox?



If so, do you know whereabouts on the X7 it is hidden? Presumably somewhere at the back?

[GiveMeABreak]

Yes, same thing Elis, also called TCU by some . Rear left hand side of the luggage area, behind the trim in this example, but won’t necessarily be fitted. These come with some of the Citroen kits, and other suppliers have a different smaller module.

[JohnD]

John, do you have an OEM electrics or dedicated C5 X7 solution for towing with the trailer?

I use a Smart Seven relay to a 12N socket. For battery and fridge on a 12S I use a voltage sensing relay.

[GiveMeABreak]

Sorry, I meant do you have a BSR (trailer ECU) fitted to the X7?

[Sloppysod]

If so, do you know whereabouts on the X7 it is hidden? Presumably somewhere at the back?

On 2011 salon, lefthand side above wheel arch in the plastic 'rack' with the parking Ecu.

[Paul-R]

Ditto position for 2013 Tourer.