Acura RLX 2014-2020 3.5L V6 Non-Hybrid VCM Disabler Harness

For the 2014–2020 Acura RLX: an inline ECT1 harness that stops Variable Cylinder Management from engaging. No OBD-II plug, no software change. It sits between the coolant temperature sensor and the factory connector, with four resistance settings to match the vehicle.

It is fully reversible and leaves the engine computer untouched.

Vehicles and years

Each row below is listed as a 100% fitment match for this harness:

• Acura RLX: 2014–2020

The non-hybrid RLX (2014–2020) uses the J35Y4 3.5L V6 with VCM. The Sport Hybrid version has a different powertrain and is excluded from this listing.

Engine generations above come from Honda and published engine references; check your VIN against them before ordering.

How the factory system decides

Honda introduced VCM on the 2005 Odyssey. It shuts down the rear bank of the V6 during cruising and deceleration by disabling those valves through the VTEC system and stopping fuel delivery. Later versions added a 4-cylinder mode, and the newest go back to 3 or 6. Each switch is timed by the engine computer using speed, load, gear and temperature inputs.

What the resistance settings do

Engine coolant temperature sensors are thermistors: their resistance falls as the engine warms up, and the engine computer reads that change as temperature. VCM is held off until the engine reaches operating temperature. By adding a small resistance in line with the ECT1 signal, the harness shifts the reading just enough that the computer does not enable VCM. The four settings (68Ω, 82Ω, 100Ω and 120Ω) exist because different engines and calibrations need a different offset. Use the setting the instructions specify for your vehicle.

Which VCM your engine has

There are three main VCM versions: VCM-1 (3 or 6 cylinders), VCM-2 (3, 4 or 6 cylinders) and VCM-3 (3 or 6 cylinders, on the later direct-injection J35Y engines). The version depends on model year, and the notes above show which applies to each covered generation. Since all of them rely on the engine computer's temperature checks, the ECT1 approach applies across the range.

What to expect

The change is most noticeable at steady cruising speed on a warm engine, where VCM previously cut in. With the harness installed, that mode change should no longer happen. Acceleration and full-throttle behavior are the same as before. If a check-engine light appears, recheck the connections and the resistance setting against the instructions, then contact support with the code.

Why owners turn VCM off

The complaints that bring most owners here are vibration or a hum through the cabin when VCM is active, a slight jerk at low speed when cylinders come back online, and concern about oil and spark-plug fouling on the deactivated bank. Keeping all six cylinders running removes the mode changes. Light-load fuel economy will usually drop somewhat, because that is where VCM saves fuel.

Installation

Work only on a cold engine. Locate the ECT1 sensor shown in the instructions for your model, release the connector lock, and fit the harness between the sensor and the factory plug. Choose the specified setting, tie the harness clear of hot or moving parts, and road-test. Nothing is cut or spliced, so the original setup can be restored at any time.

Before you install

Start with a healthy engine: no check-engine light, coolant at the correct level, a thermostat that opens normally and no misfire history. The harness relies on a working ECT1 sensor; if that sensor is faulty, replace it before installing the harness.

Check before you order

• Your model and year match a row above (2014–2020 Acura RLX).
• Your vehicle has the V6 with VCM described in the notes above (not a four-cylinder, hybrid or turbo model).
• The connector at your ECT1 sensor matches the product photos.
• Engine swaps, aftermarket ECUs or modified wiring need a fitment check from support first.
• Unsure? Send your VIN to support@automotivebypass.com.

Warranty and returns

Shipping is free to the contiguous US. Orders leave in 1–2 business days and usually arrive 3–4 business days later. Returns are accepted within 45 days with pre-approval; a 20% restocking fee applies and the buyer covers return shipping. The part carries a 3-year limited warranty, and support@automotivebypass.com answers Monday to Friday, 9–5 Pacific.