Disclaimers

Maximizing Your Cummins Diesel Performance: The High Idle Advantage

The Ultimate Guide to Ram Cummins High Idle

Whether you are a seasoned Rig Ready Ram owner or new to the heavy-duty world, understanding your truck's secondary features is key to longevity. At Redwater Dodge, one of the most frequent questions we receive in our service bay is: "How do I use the high idle feature on my new Cummins Diesel?"

While the technology inside the 2026 Ram 3500 has advanced significantly, the process for engaging high idle has remained remarkably consistent for the last 15 years. This feature is designed to increase your RPMs while parked, preventing "wet stacking" and ensuring your cabin warms up quickly during those freezing mornings.


Step-by-Step: Engaging High Idle on a 2026 Ram

To engage the high idle on your Cummins-powered truck, follow these simple steps while the vehicle is in Park:


  1. Start the Engine: Ensure the truck is running and in a well-ventilated area.

  2. Enable Cruise Control: Locate your cruise control buttons on the steering wheel. Press the "On/Off" button to activate the system (you will see the cruise light on your dash).

  3. Engage the Idle: Press the "Set -" (Minus) button. Your truck will automatically jump to approximately 1,000 RPM.

  4. Adjust the Speed: If you need more power or a faster warm-up, press or hold the "Set +" (Plus) button. This allows you to ramp the idle up to 1,500 RPM.


Expert Pro Tip: If you want to reach operating temperature even faster, engage your Exhaust Brake while the high idle is active. This adds a slight load to the engine, allowing it to reach a comfortable temperature within 10–15 minutes.


Common Questions About RAM High Idle


Q1: Why should I use the high idle feature?

A1: High idling is essential for diesel engines in cold climates. It prevents the engine from cooling down too much while idling and ensures complete combustion, which protects your fuel injectors and DPF system.


Q2: Is the high idle process different for older Ram trucks?

A2: Surprisingly, no. The logic for the Cummins high idle has remained virtually the same for the last 10 to 15 years. If you have a 2015 or a 2026, the Cruise Control method is your go-to.


Q3: What is the maximum RPM for high idle?

A3: By using the "Set +" button, you can manually increase the idle up to 1,500 RPM.


Q4: Can I use high idle while the truck is in gear?

A4: No. For safety reasons, the high idle feature will only engage when the truck is in Park (for automatics) or Neutral with the parking brake set (for manuals).


Q5: How do I turn high idle off?

A5: Simply tap the brake pedal or turn off the Cruise Control button on your steering wheel. The engine will immediately return to its standard base idle.


Q6: Does using high idle waste a lot of fuel?

A6: While it uses slightly more fuel than a base idle, the trade-off is better engine health and a faster warm-up, which can actually save you fuel by getting the truck into its "efficient" operating temperature sooner.


Q7: Can I use the exhaust brake and high idle together?

A7: Yes! As mentioned by Matt at Redwater Dodge, using the exhaust brake creates backpressure that helps the engine generate heat much faster.


Q8: Why won't my high idle engage?

A8: Common reasons include the foot brake being depressed, the vehicle being in gear, or the "Cruise Control" master button not being turned on first.


Q9: Does high idle work with remote start?

A9: Most 2026 Ram 3500 models have an "Automatic High Idle" that may kick in during remote start if the ambient temperature is low enough, but the manual method gives you more control.


Q10: Is it bad to let a diesel idle for a long time without high idle?

A10: Yes. Extended idling at low RPMs can lead to "carbon packing" and cylinder wash. High idle is the solution to these common diesel maintenance issues.


Q11: Does this work on the Hemi gas engines?

A11: No, this specific Cruise Control "High Idle" hack is unique to the Cummins Diesel powertrain.