Purpose of High Idle Switch: What Does High Idle Do?

Owners use this switch for different reasons and they are all valid. You want the high idle switch on to protect your engine when you are not moving down the road but sitting still for a long period of time. It is there when you need it.

We have come across many reasons why you have a high idle switch on your dashboard. One reason is to give you a faster warm-up time when you first start the motor. But not everyone uses this feature as they do not see the value of its purposes.

To learn more about the high idle switch, just continue to read our article. It has the information you want to know about. This switch may be important to use for some situations but not all drivers agree and have not used it in a very long time

What is The Purpose Of The High Idle Switch?


The basic purpose would be to give your engine more power. This power comes in handy as Winnebago advises you to use it when you are putting your slides out. You keep your engine running at this time and the extra power makes sure those slide-outs work better.

Also, this device is put in to prevent wet stacking. This is a situation where the low idle is not hot enough to burn all the fuel entering the cylinders. The unburnt fuel mixes with the oil in the cylinder and dilutes it. This issue can cause some engine damage.

That damage would be excessive engine wear. Then it is also used to keep the oil pressure up. Low idle does not produce a lot of oil pressure. A lack of oil pressure can also cause engine troubles.

Other owners use the high idle switch when they are operating special equipment attached to their vehicles, like a winch.

What Does High Idle Do?

There is a difference between high idle when you have a switch to engage that feature and high idle when you don’t. The former option is designed to help your engine perform better when it is not driving at all. You are just sitting there waiting for traffic, operating different pieces of equipment, and so on.

There is nothing wrong with this feature as it is designed to work that way on purpose. However, if you have a high idle and you either have not engaged the switch or do not have one, then you have a problem with your motor.

There is a screw on your engine that can adjust the high idle down to its proper level. It just takes a little turn of the screwdriver to get this done. However, if you do not adjust the idle level you could cause excessive wear and tear to your engine.

Or your foot can slip off the brake and your vehicle lurches forward and hits the car in front of you. In either case, you will get more power whether you want it or not.

Diesel Engine High Idle


For modern diesel engines, you only need to warm up your motor for 3 minutes. Then you can put it into gear and get going to your next destination. Older diesel engines needed about 5 to 10 minutes of warm-up if they were going to operate up to expected levels.

You may not think about it but idling happens to cause more wear and tear on a motor than starting and stopping it does. In fact, idling places two times the wear on an engine than normal driving does.

This means you have to be careful when using this mode. While the motor is designed to idle at high levels, this should be done for short periods of time only.

High Idle Switch Gas Engine

It is possible to do this. It may take about 15 feet of 18 gauge wire and a Pin for the ECM but it is doable. Some owners have done this already. Whether it is a good idea or not remains to be seen.

Some people have advised other owners not to do this as there is a safety factor involved. You can have a run-away situation if the idle gets too high or the switch breaks.

Others have questioned the legality of this move and you would have to check with the governing authority in your state to see if there are rules prohibiting this move. The reason most people add the switch is that they live in a very cold state and need their car or truck to heat up faster.

Not everyone will need this switch so your location and purpose will play a role in if you install it or not.

Is High Idle Bad For Diesels?


Yes, it can be if you let the engine idle for too long. As we reported earlier, the high idle can cause 2 times the amount of wear to your engine than normal driving conditions.

This mode is okay for short periods of time and most modern diesel engines can handle it for the allotted 3 minutes most diesel engine makers allow. There are other applications that need high idle but again, you do not want to remain in this mode for a very long time.

While the purpose is good, many owners have had it removed to protect their motors from damage. They have reported nothing wrong with their motors once they had them disposed of.

You will have to be the judge on whether this mode is valuable to you or not and then act accordingly.

Low Idle vs High Idle

This debate is not really a debate at all. Both modes will eventually cause a lot of engine wear if you idle too long. The difference between the two will be available power. The high idle will produce more.

Plus, the high idle will build the oil pressure better and quicker. This is handy to have on cold mornings. Then if you put your transmission in neutral, the transmission will cool down faster on high idle.

This can be an important piece of information as some RVs can have their transmission overheat while running and get sent to limp mode. The high idle will cool it down and return your RV back to normal running conditions.

High idle, for the most part, has better benefits than the low idle function. Those benefits may over-shadow the negative wear and tear aspect that comes with idling at any speed.

When Should You Use High Idle?


The proper time to use this function is when you need extra power. Those situations tend to come along at different times and it is possible to use this feature for the wrong reason.

It will be needed when you are using more electricity than normal. If you need to operate a winch or put your slides out, and so on having the high idle feature engaged will be beneficial.

Also, if you live in a state that gets very cold, a high idle is ideal when you need your engine warmed up quickly. Other people use this feature when they are in limp mode due to an overheating transmission.

The high idle cools the transmission and gets them going again. There are some very good reasons why you should use this feature but it can be overdone and you will cause your engine to lose its longevity.

Do I Need a High Idle Switch?

Not really. If you do not mind holding your foot on the gas pedal for a few extra minutes, you can achieve the same results. Not everyone can do that but you may save yourself a few hundred dollars by using this option.

Some people use it in hot summer areas to boost their AC. It helps but again, it is not necessary. Then with the short warm-up time needed for modern diesel engines, you may not need it in the morning anyway.

With a 3 minute window, a high idle is not going to make that much difference. Some owners have had this switch come with their truck but have never used it. Whether you need it or not is up to you.

You may find that you wasted the money as it is not used as often as you thought it would. It does come in handy when you do need it but your foot is free and you could use the money elsewhere.

Some Final Words

The high idle switch does help in certain circumstances. But you have to evaluate your work and living situation to determine if you need this option or not. Some people never use it while others use it a lot.

Idling at either level will wear out your engine faster than if you drove many miles every week. So use it with care if it is installed in your vehicle.

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