The “Idle Up” switch is no longer visible inside the Land Cruiser. Last week we were lucky enough to see the Toyota Land Cruiser 250 for the first time. This was a pre-series unit, very close to final configuration. Toyota Land Cruiser 250 VX orders have just started And whose first units are scheduled to enter service next October.
We have talked in detail about the new generation off-roader of the Prado series or without weight Of the Land Cruiser, which is now starting its commercial life to replace the 150 series, but until it appeared before our eyes we had not noticed that the Toyota Land Cruiser with a diesel engine had been around for decades. The controls installed in the cruiser have disappeared. And in other 4×4 from the Japanese firm.
We are talking about switches with legend labels Idle Up, which we can literally translate as “high idle”, although we prefer the expression “forced idle”; A switch about which you can find a lot of information on the Internet, but unfortunately, also a lot of misinformation.
What is Toyota Land Cruiser idle up button?
As we’ve already suggested, the Idle Up switch activates or deactivates the “Forced Idle” function. When we press it, the control unit that manages the engine electronics (ECU) receives a command to increase the idle speed (to about 1,200 or 1,500 rpm instead of the typical 800 rpm that typically occurs in diesel engines, What it does is act on the intake butterfly, which allows additional amounts of air into the combustion chambers and results in additional amounts of fuel coming into the feeding system.
In the past, many SUVs had a forced idle system via a small lever that slightly tensioned the accelerator’s Bowden cable, but although this method was more rudimentary or “less precise”, the function accomplished was the same: Forcing idle speed.
Subsequently, a solenoid valve activated by the idle up switch allowed the engine to use an additional intake air duct, which again served the function of increasing idle speed.
But regardless of the mechanical resource used, The idea was always the same: allow greater flow of fuel into the combustion chambers to maintain a higher idle speed. Without the need to use accelerator control. And this brings us to the million-dollar question: What is the purpose of the forced idle or idle up mechanism?
What is Idle Up or Forced Idle for?
basically, The main function of the idle up switch is to prevent the engine from stalling under certain circumstances, Such as on a complex path in which a great resistance must be overcome to progress, either because the terrain has stairs or some other difficulty that forces the wheels to require more torque than available or because we are excessively loaded. There have been, to put it another way, some examples.
This is something that we can solve by stepping on the accelerator… as long as we are not in the vehicle. and it’s the same The Idle Up button is especially practical for maintaining idle speed if we have attached some type of implement or implements to the transfer case power take-off, Something that isn’t common today, but was the case years ago, especially in what Toyota calls “general markets” and what we typically call developing countries.
Nobody uses their brand new Land Cruiser as a tractor these days, and the winches are electric, but that wasn’t always the case. On the other hand, since the appearance of beginning Automatic, idle up switch less necessary. And with the normalization of electronic power management and automatic transmissions coupled by a torque converter managed by a control unit, idle up is simply an unnecessary mechanism.
Thus, regardless of the circumstances in which we rotate (towing, trialling, running a pump to drain water, etc.), our Land Cruiser is not going to stall or roll over at an abnormally low idle speed because the rotation speed of the engine The speed is constantly monitored and the engine ECU adopts the necessary strategies to keep this speed constant, so forced idle or idle mechanisms are, today, absolutely unnecessary.