C5 X7 loss of Cruise Control

[bigblackfalco]

Hi,
my 2009 C5 2.0 HDi 6 Sp manual has totally lost use of the cruise/speed limiter feature. The switches operate correctly but I just get a flashing 'hyphen -' mark where you would normally get to set the desired speed.
The system stopped working directly after a near side front suspension damper was replaced by a local non-Citroen workshop.

At first I thought maybe it just needed a BSi reset after the battery had been disconnected, but doing a BSi reset didn't solve the issue.
There are no ABS warning lights. The rest of the car is working perfectly.

Obviously there is a high chance that a connector or wire is the culprit at the location where the damper was changed.
Would this always flag up a 'warning lamp' on the dash or would it just be logged as a fault code in the ECU?
I don't have any form of diagnostic tool/Lexia etc, so would like to know what would typically happen in this instance, or if anyone else has experienced this exact same situation?

No problem with taking the wheel off and doing some electrical fault finding myself.
Is there anything physically I should be looking for in particular?

Many thanks

Bailey.

[GiveMeABreak]

When an activation request is received, if activation of the speed limiter or cruise control function is not possible, the reference speed displayed (value or dashes on the display) flashes for 7 seconds. This is either a fault, or the value of the speed set is not being received.

Either way it really needs Diagbox to get some fault codes as this can be a symptom of the engine ECU switching off the function die to an issue somewhere or valid data not being received. If there was ans ABS / ESP ECU issue with the wiring from this ECU, I would expect a fault and warning lamps to come up in the dash.

If you can get some codes, post them up here with the VIN.

[bigblackfalco]

When an activation request is received, if activation of the speed limiter or cruise control function is not possible, the reference speed displayed (value or dashes on the display) flashes for 7 seconds. This is either a fault, or the value of the speed set is not being received.

Either way it really needs Diagbox to get some fault codes as this can be a symptom of the engine ECU switching off the function die to an issue somewhere or valid data not being received. If there was ans ABS / ESP ECU issue with the wiring from this ECU, I would expect a fault and warning lamps to come up in the dash.

If you can get some codes, post them up here with the VIN.

Hi Mr GiveMeABreak
For it not to be registering a 'warning lamp' on the dash, what could it be physically if we took into account the removal of front wheel/strut assembly. Dirt/corrosion/ omission of spacer/incorrect reassembly etc??
Just trying to find something simple and that can physically be seen with the naked eye before going down the fault code route.

Many thanks

Bailey.

[GiveMeABreak]

Hi Bailey

Well the ESP / ABS Block and ECU is located on the passenger side approximately under the fuse box shown at (12), so it is quite possible if you were having the passenger strut replaced on the left side (you didn't specify) that something has upset one of the wires or connectors, or some fluid has penetrated the area.

Without a fault code I can't point you further. It could be a totally unrelated issue and a red herring of course, if something else has caused the engine ECU to deactivate the cruise or speed limiter.

[bigblackfalco]

Hi Bailey

Well the ESP / ABS Block and ECU is located on the passenger side approximately under the fuse box shown at (12), so it is quite possible if you were having the passenger strut replaced on the left side (you didn't specify) that something has upset one of the wires or connectors, or some fluid has penetrated the area.



Without a fault code I can't point you further. It could be a totally unrelated issue and a red herring of course, if something else has caused the engine ECU to deactivate the cruise or speed limiter.

Ok it was a nearside strut, so this would tie in with location of ABS ECU etc.
Once the weather improves in North East Scotland, I shall venture out to stick my head under the bonnet.
Thanks again

[bigblackfalco]

Right,

I'm hoping I've found the culprit. A broken positive wire to the brake wear indicators. Does this complete/have any influence on the Cruise control circuit?

This is the first thing I found when I took the wheel off. Have;t looked any further.

If this is the cause, how much of this cable assembly do I need to replace? I can't seem to push the main rubberised cable block out of the earthing mount frame support. This could be due to corrosion or the fact it was press fitted at the factory? Annoyingly the wire has snapped off flush with the housing so I can't even splice the 2 wires together.

Hope the pics are self explanatory.

Bailey

[GiveMeABreak]

The only thing that would affect the cruise control concerning the brakes is the actual brake switch at the pedals which disengage the cruise when pressed.

The brake wear wiring won't impact on this as it's just a resistance-based system that changes resistance as the pads wear down to the pins and throws the light up.

[bigblackfalco]

The only thing that would affect the cruise control concerning the brakes is the actual brake switch at the pedals which disengage the cruise when pressed.

The brake wear wiring won't impact on this as it's just a resistance-based system that changes resistance as the pads wear down to the pins and throws the light up.

Thought you might say that!

In regards to the brake switch, I can clearly see that the brake lights are working correctly.
Does the clutch pedal have a switch on it too?

I've just sat in the car and double checked the ESP system, switching it on and off. Works fine.

Seems weird to not throw up a fault indicator on the dash.

Back to the drawing board!

Thanks.

[GiveMeABreak]

You really do need to get Diagbox on it for a diagnostic, as otherwise it will be clutching at straws. There is an issue where the speed request is not getting through, so it flashes up the dashes. It may also provide a warning message in the matrix display along the lines of "Impossible to set Cruise, enter speed first" or something like that.

As said if there was an issue with the ESP ECU - i.e. a wheel speed sensor, then that would knock a warning up and deactivate speed functions - but that hasn't happened.

But before that, let's go back to basics:

It is possible you may have deactivated Cruise Control by hitting the button accidentally on the steering wheel. Look at the picture below and specifically the lowest button that looks like a stopwatch. Pressing this deactivates the system and therefore regardless of pressing the speed increase or decrease will prevent it from working. I suggest you start the engine then press this button to activate the function, then go for a drive and test it.

[bigblackfalco]

No it's def working and switched on. Just not getting any speed info getting through to it.

[GiveMeABreak]

Ok, so back to a diagnostic needing to be done I think.

[bigblackfalco]

Hi,

actually got round to buying a code reader at last! Occasionally get an emissions error pop up, but a good blast for 20 mins normally sorts it. Must be related to the glow plugs.

It shows there are codes related to the cruise control.

I've tried clearing them, but even without actually driving, the errors come back.

[Stickyfinger]

The only thing that would affect the cruise control concerning the brakes is the actual brake switch at the pedals which disengage the cruise when pressed.

The brake wear wiring won't impact on this as it's just a resistance-based system that changes resistance as the pads wear down to the pins and throws the light up.

Thought you might say that!

In regards to the brake switch, I can clearly see that the brake lights are working correctly.
Does the clutch pedal have a switch on it too?

I've just sat in the car and double checked the ESP system, switching it on and off. Works fine.

Seems weird to not throw up a fault indicator on the dash.

Back to the drawing board!

Thanks.

YES, there is a clutch switch as well (no 6).........if there was not the engine would over rev when you dipped the clutch (if cruse was controlling the speed at the time)

If I recall correctly the brake switch has a dual function, brake lights can still work but the cruse signal part can fail...........( ? maybe wrong on that? )

[GiveMeABreak]

Before looking at the other fault codes, look at resolving this one first, as if there is any issue with the ESP system, cruise control and speed limiter are the first functions to be deactivated, along with others like hill start assist etc.

Fault Code:	U0122
Description of Fault:	CAN communication: Absence of communication with the ESP ECU. Description of the diagnostics: Absence of communication with the ESP ECU
Conditions for Fault to clear:	Driving for 5 minutes
Downgrade Modes whilst Fault is active:	Deactivation cruise control until the next time the ignition is switched on
Symptoms:	-
Suspect Areas:	CAN network

[bigblackfalco]

Before looking at the other fault codes, look at resolving this one first, as if there is any issue with the ESP system, cruise control and speed limiter are the first functions to be deactivated, along with others like hill start assist etc.

Fault Code:	U0122
Description of Fault:	CAN communication: Absence of communication with the ESP ECU. Description of the diagnostics: Absence of communication with the ESP ECU
Conditions for Fault to clear:	Driving for 5 minutes
Downgrade Modes whilst Fault is active:	Deactivation cruise control until the next time the ignition is switched on
Symptoms:	-
Suspect Areas:	CAN network

Thank Marc.
I didn't realise there's a fuse for the ESP according to the Handbook.
Is it in the glove box or engine bay?
Is the Can Bus Box/ wiring obvious?
Bailey.