Steering Wheel Head Unit Controls - irregular behaviour

[dave_xsara]

Many years ago now, I had to replace the head unit in the Xsara - I got the correct patch lead for the steering wheel controls and everything has been working fine for a number of years - until a few months ago.

What I've noticed is that at seemingly random times pressing the volume lowering button will increase the volume, pressing the volume increase button will cause a channel seek and pressing the memo buttons can result in mute. This persists for an unknown period of time - I revert to the controls on the head unit.

After a while (usually within the same journey) without any adjustment or interference from myself the correct behaviour returns.

Has anyone had this issue before? There has been no work done in the area of head unit - I'll whip it off maybe at the weekend to check, but just wondering if anyone else encountered this to save me some investigation time!


Thanks.

[Stickyfinger]

I have the same problem with my Xantia...I was waiting till winter to take the wheel off as I have some dash lights to replace.

I would be interested in what is happening.

PS, also have a AirBag lamp on so I suspect the ribbon inside is failing.

[white exec]

On the original (ex-factory) installation, the steering wheel controls, when pressed, switch in a set of different resistances (each button has its own value) which the head unit recognises, and executes that command. The resistors sit on a small p.c.b. in the steering wheel centre.

If the connections between the wheel switches/p.c.b. and the head unit are not good (dirty contact, for example) the commands can be mis-interpreted, and wrong actions performed.

Check the multi-way cable connectors at the head unit (might only be a 2- or 3-way connector by the time it reaches the back of the radio) and in the steering wheel boss. There is also a flexible connection at the steering wheel to cope with steering wheel rotation.

Caution: if removing wheel centre, take the recommended powering-down/disconnection precautions with any air-bag explosive capsule fitted there.
_________

Head units and wheel controls must be matched (the right resistance values for that make of radio). If a non-original (updated) head unit was installed, with an "interface" module (which converts the resistance values to new values), this could be misbehaving, or not getting correct power.

[dave_xsara]

Is it possible to blast some contact cleaner into the switches as a first attempt without having to take the wheel centre off?
I presume the switches do not prise off easily from the outside - I'd imagine the connections would be quite brittle now after 20 years.

It's been working for for literally years now so I think it is just wear/dirt on the contacts.

[white exec]

Not sure about Xsara, but XM steering wheel centre is removed by undoing screws on the back side of the wheel. Rotate wheel to see (mirror) and get access to the screw heads. This centre contained the air-bag module (can be unplugged after the proper procedure - likely battery disconnection, and wait), which gives access to the steering wheel switches. You'll see whether they are amenable to contact cleaner.

Do post your VIN, Dave, in case we can unearth any circuit/parts details for the controls.

[tich731]

When one of the cruise control buttons on my C6 stopped responding, I blasted Servisol Contact Cleaner down the outside of each button, allowed to dry, and then full operation was restored.

[Mandrake]

Can't use the radio in my Xantia anymore. It too seems to have a case of steering wheel button-itis.

It usually keeps going into "scan" mode where it will keep jumping through the memories with no way to stop it...

[GiveMeABreak]

I have the VIN already for Dave.

This system has the separate remote harness and buttons as shown below:

No longer available of course (Item 7 on the diagram, Part 4112FA)

There's a brand new one here for £19.99:

https://www.ebay.co.uk/p/Citroën-4112FA/659103708

I suspect the contacts on the button may be worn - a clean up may be worth a shot, but Lexia should be able to test the button presses for you. With the constant turning, it may have caused a break / tear on the ribbon connection also causing an intermittent issue.

Here's a better picture:

[white exec]

Tich, Simon...

What make/model of radio (head) units are we dealing with here?

[dave_xsara]

Marc, does the Lexia work with non OEM head units?
There was an error message when I was trying associated with the head unit when I was trying to fix that air flow issue.
I'll take another look at it - I assumed it was just yapping because it was non OEM.

[GiveMeABreak]

No it won't Dave. Lexia is designed to work with specific OEM or approved equipment. It can only be used to de-install an OEM unit, to let the system know it is not there to prevent errors.

[Stickyfinger]

Is a Xsara 2.0HDi 90 that clever ?

[GiveMeABreak]

Let's not knock it - it still has a BSI and multiplexing, and was one of, if not the first PSA vehicle to have 'Auto PC' / Windows CE as an option - a blessing or a curse, depending on you viewpoint

• The first "Windows" car
• The first communicating car equipped as standard with a dual-band GSM communication system and a colour navigation unit.
• The first car to be equipped with a voice recognition system controlling operation of the information system.

[white exec]

Radio make and model?

[Stickyfinger]

Let's not knock it - it still has a BSI and multiplexing, and was one of, if not the first PSA vehicle to have 'Auto PC' / Windows CE as an option - a blessing or a curse, depending on you viewpoint

• The first "Windows" car
• The first communicating car equipped as standard with a dual-band GSM communication system and a colour navigation unit.
• The first car to be equipped with a voice recognition system controlling operation of the information system.

Always a worry when Citroen are first with electronics