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 FAQ #205
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C4 Brake Switch causing ESP/ABS fault or Speed limit error message, Switch replacement guide.
The C4 is prone to an ABS, ESP or Speed Control Limit error message which is invariably caused (but not always) by a faulty brake switch sending an erroneous message to the ECU

Hopefully I have fixed the problem, here is a how to.

In the passenger foot well, there are three plastic rivets which need to be removed and placed safely together.

They are easily removed by griping the inner part and pulling out.

Here's the Switch which comes as a kit with a new loom which I was told has a resistor in it.

To remove the switch, grip and rotate the switch 90 degrees anti clockwise, the disconnect the connector.

When replacing the old switch for the new one, you need to set the plunger new switch to the same length as the old one. This is done by pushing or pulling taking care not to damage it.

This photo shows where to measure/compare the "plunger"

Replace the switch by pushing it into the hole and rotating clockwise 90 degrees. turn on ignition and check that the brake lights work, if not the switch plunger might not be set to the correct length.

Hopefully now you won't have the ESP/ABS warning.

The loom simply plugs in to replace the old one, no reprogramming required.

Part numbers are:

453467 for the kit (switch and wiring loom). RRP £35.95 Inc VAT from Citroen or £24.00 from - Click Here - (Sept 2015)

Prices will vary due to Citroen pricing policy, exchange rates, VAT changes, dealers pricing policy, etc. etc. and are for guidance only.

jimux wrote ...

The above is based on the car models, not the Picasso.

For the Picasso the switch is protected by a black cover under the glove box. Do this:

Remove the 3 plastic rivets under the glove box.
Remove the torx screw holding the glove box underpanel to the centre box.

Pull sideways on the bottom of the panel and fold downwards.

Now use a short 10mm ring or flat spanner to remove the top nut from the cover. You are working blind but the long thread on the bolt helps keep the spanner in place.

Use a long tube 10mm spanner to remove the bottom nut.

Both nuts are only lightly tightened and a bit of 15mm copper pipe squashed at the end would do instead of a tube spanner.

Now a quarter turn anti-clockwise will free the switch.
The switch harness has virtually no slack and must be attached to the new switch before re-assemble.

The torx screw is deeply recessed, I use a little insulating tape to stick it to the torx screw-driver to get it back in.
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FAQ Posted by Ham
Info Created: 25 June 2010
Last Updated: 05 September 2015