I take your point, although I think there is still a valid discussion to be had.
As far as I’m concerned the increase in revs is 100% linked to pressing the clutch pedal. And the amount of the revs increase is far in excess of what might be attributed to any reduced load because the gearbox input shaft ceases to be driven.
So what I thought was a reasonable deduction is that the whatever is actually going on with the revs is triggered by the movement of the clutch switch plunger (I assume is has a plunger, rather like the brake pedal switch?) making or breaking a circuit, and that this change of state then got communicated back via the canbus to the ecu which then, for whatever reason, gave an instruction to the throttle body to open up a bit.
To be totally honest I can’t recall if this rev rise was present from Day 1 of ownership or only from the point at which the wiring was loom was modified. (This may seem a bit strange, but I’m actually the car’s co-owner and driving it isn’t what I do with it - so I’m not even sure I ever drove it prior to the wiring changes.) The wiring changes were undertaken by a motorsport professional and with total awareness that canbus systems have lots of knock-on interactions that may be far from obvious.
If indeed the the function of the clutch switch is only in relation to traction control and cruise control, neither of which systems are any longer functional on this car (the wheel speed sensors are disconnected), is there any sensible reason why this rev increase occurs? If cruise control was fitted and active at the time I assume it would disengage it? (I’ve never has cruise control on a manual car). But how would sensing a clutch pedal action contribute in terms of traction control?
What I think I will try is removing the switch from it’s current position and either discarding it completely or tying is off somewhere behind the dash. If anyone has any better ideas I’d be very glad to hear them.