2.0HDI hunting at idle

[dave_xsara]

Still doing this - admittedly not as frequently now as previously. Would a new fuel filter help here, service interval is due soon.

[dave_xsara]

Marc,
Would this be applicable to the HDI 90 as well, I didn't think applied although taking out and cleaning the switch contacts can do no harm?

viewtopic.php?f=3&t=55708&start=15

https://www.honestjohn.co.uk/forum/post ... tm?t=36574

[GiveMeABreak]

Possibly. On the C3 I was referencing in my old thread (ours is a 1.6 HDi DV6ATED 92 BHP), there is a Primary and Secondary brake switch. As far as cruise control goes for example, the cruise is deactivated where the principal brake switch status is different from the information on the secondary brake switch status.

The main brake switch data is received by the ESP / ABS ECU
The secondary brake switch is received by the Engine ECU, as are the accelerator and clutch switches.

Now there are a lot of information exchanges between the various systems, but it would seem that the brake switch(es) do play a big role here - and our issue was solved with a replacement brake switch strap unit.

Of course there can be other reasons for hesitation or flat spots....

[dave_xsara]

Thanks - I didn't think it would have an effect on mine as it is a single switch and there is no cruise control.
There are two sets of wires coming out of the switch which I had presumed went to each rear light cluster.

[GiveMeABreak]

Unfortunately I don't have the correct electrical diagram for your car, given the age, so can't help with the circuit

[Hell Razor5543]

On the later C5 Mk1 (I know you may not be talking about a C5, but this is relevant) the brake switch is actually TWO switches in one casing; one for the brake lights (push to make type switch) and the other is for the Cruise Control (push to break type switch). This accounts for two sets of wires.

[GiveMeABreak]

This system is not the same James, no cruise and different setup - 2 terminal switch not 4.

[Hell Razor5543]

Thanks - I didn't think it would have an effect on mine as it is a single switch and there is no cruise control.
There are two sets of wires coming out of the switch which I had presumed went to each rear light cluster.

Marc, THIS is why I wrote my previous post in this thread.

[dave_xsara]

Do you have an image of the switch?

The one on my car looks like the following:




It would appear to be a single switch too (https://www.buycarparts.co.uk/hella/937169) if these are the correct part numbers:

CITROËN, PEUGEOT (4534.11)
CITROËN, PEUGEOT (4534.51)

[GiveMeABreak]

That's looks like the correct one for your car. I've already checked using your VIN. It's why we do to avoid guesses and comparisons to cars that are completely different.

Part 453451: 2 pins as I said earlier. £15.53 from Citroen

[dave_xsara]

Okay - might try a continuity check this weekend to see where these are going in the absence of a wiring diagram - still think it will be to each rear cluster.

[GiveMeABreak]

453411 isn't a recognised part for Peugeot or Citroen

[dave_xsara]

Must have been a typo on their site as the one you have is listed.

Okay - don't give me a bollocking for this, but...
Faffing around on Google I've found a pdf for Xsara Wiring Diagram and it shows as follows:

Note how the output from the 'stoplight' switch routes to both the fuel injection (L) and the rear cluster and that it is a single switch serving both functions:

See here that the stop light switch feeds into 207 (ECU).
EDIT: Just noticed clutch switch (225) on this diagram - and the inertia switch (212) which is the red fuel cut off switch located in the engine bay.

I am aware that this may not be the offical wiring diagram for my specific vehicle - the PDF has no official stamps or identifying text, but in the absence of official diagrams it does provide a level of validation that the brake switch does feed into fueling even for cars without Cruise Control.

[GiveMeABreak]

You have to bear in mind that the Xsara II went through several major mods including the electrical architecture - after your RPO. So that will not necessarily be relevant to your vehicle because it was an earlier build. Your Xsara doesn't have 'drive by wire' accelerator pedal, it's a mechanically operated accelerator, so works differently than later systems as one example.

Your RPO is 08802.

As for the diagrams - they are Haynes ones - say no more.

Example the second diagram section you highlighted is showing 1383, which is the Vehicle speed sensor power supply - nothing to do with the stop lamp switch. And also note the title of the diagram 'Typical HDi Diesel Engine Management System' - There's nothing typical about it at all.

I wish I had the official one to show you now

[dave_xsara]

Never worry - I thought as much, but thought I'd throw it up anyway!