'Idle Up' Switch . What is its function ?

[red hilux Member Find all posts View Profile Close red hilux]

Is it possible to temporarily trick the ECU to think its cold??

Im guessing its using the engine temp sensor (complete guess)

If it does then make the idle up switch trigger a relay that puts a resistor into the circuit.

[Bushbasher Out of control poster! Find all posts View Profile Close Bushbasher]

Why, what for. It only raises the engine speed a little. Not like the hand throttle on an old Tojo or Landie.

[Mozz Member Find all posts View Profile Close Mozz]

Anyone worked our which temp sensor initiates this function and where it's located. I'm pretty sure there is one for the outside temp display on the dash but not sure if this is the one.

[Jinders Lurker Find all posts View Profile Close Jinders]

It increases the revs at idle when the engine is cold to help it warm up quicker.

Cheers Andrew

Hmmm...? I'm very new to this, but the cold temp suggestion sounds counter-intuitive to me. The ECU has multiple temp sensors. Why wouldn't they give the ECU control of idle speed to match the engine need of the ambient temperature. If this were important, why would they allow the vagaries and knowledge of diverse drivers to decide to use or not use this switch.

As well, the manual states for both petrol and diesel: "Engine should be warmed up by driving, not in idle. For warming up,drive with smoothly turning engine until engine coolant temperature is within normal range."

So why would Toyota provide a switch supposedly to warm up an engine in a cold environment by raising the rev count of idle speed, and then explicitly instruct drivers in the manual to NOT warm up the engine by idling it.

Further the Prado's we drive in Australia are explicitly kitted out for the Australian and ancillary market. Toyota's business model for our Prado market is not one in which they include extra bits that are appropriate to other markets.

(Searching for this though, did alert me to the need to idle my diesel engine for at least a minute after coming off a high speed journey. As I stated: I'm very new to this, and had never had this requirement put to me in my forty years of diverse driving experience. I helped choose my partner's diesel 2010 Fiesta which hada massive clearance reduction as new in 2012, and which is still running beautifully - but I didn't have that info. Perhaps though it is only a concern for heavier higher-torque diesel engines?)

My understanding is that this switch is to increase the rate of revs in idle to allow the vehicle to "walk up" a steep incline - presumably to do so without the risk of needing to change gears?

I'm not sure how that might transfer to the need for increased output from the alternator as identified by those using their winches. As far as the experience of it not working, Perhaps it is programmed to not raise the idling rev count if the vehicle is not moving forwards - or not struggling up an incline. Worth testing.