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What is this bit and what does it do?

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No picture, sorry.

On the outlet from the clutch master cylinder in my Td5 110 there is an electrical connection. What is this measuring or controlling?

I ask because a friend was bemoaning the poor running of his Td5 90 when off road - read "in low range" - and another, third party, disconnected this connection and the high/low switch on the transfer box. Now, I know that disconnecting the high/low switch has the effect of giving the high range throttle map in low range too, but what effect has the other dis-connection had? Said friend now reports that the 90 is transformed.



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RAVE info says clutch pedal switch connection C0667 it supplies the engine managment ecm with a clutch pedal position signal.

Stops the engine racing if you declutch with revs on. Probably also part of anti stall system.

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The clutch pedal switch is located on the clutch master cylinder and is activated when the clutch pedal is operated.

The ECM uses the signal from the clutch pedal switch to provide surge damping during gear change. Surge

damping stops engine speed rising dramatically (engine flaring) during gear change. Surge damping assists

driveability as follows:

• Smoother gear change.

• Greater exhaust gas emission control.

• Improved fuel consumption.

Input / Output

When the clutch pedal is in the rest position, the clutch switch is closed. This allows a feed to flow from the switch (C0667-1) to the ECM (C0658-35) on a black/white wire.

When the clutch pedal is pressed the switch contacts open, cutting the feed to the ECM.

The clutch pedal switch can fail in any one of the following ways:

• Switch open circuit.

• Short circuit to vehicle supply.

• Short circuit to vehicle earth.

In the event of a clutch pedal switch failure surge damping will be inactive.

I suspect disconnecting it has made the engine seem 'super responsive'.

This can be a help, it can also cause traction to be broken when that is not the best idea.

Suck and see how it suits your driving style / conditions?


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I might try the same modification, thanks guys. I certainly do not like the low range throttle ramp - if I hit the throttle it is because I want power then, not in a second and a half!


Just unplug the grey plug that goes to the switch on the transfer box and bridge the two pins on the harness side of the plug... then the ECU thinks it's in either high to low range all the time ;) (just depends if yours is wired up normally, or is on the of the odd Td5's that work the other way round)

When you drive it you will very quickly notice the difference....


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Chris, that will be the antishunt thing as above we discussed taking off whilst in the lakes, i believe it holds the engine revs for longer after the clutch is pressed to help down changes ie the engine doesnt go straight to idle it drops revs slowly. PITFA if you ask me, just disconnect it.

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