2018-2020 Acura RLX Start Button: Solving No-Start Issues & Choosing the Right Part
This guide covers the critical differences between the hybrid and non-hybrid ignition switches and helps you diagnose common starting problems that are often mistaken for a bad switch.
- The most critical step is matching the part to your powertrain: use part numbers starting with 35881-TY2 for non-hybrid RLX and 35881-TY3 for the Sport Hybrid.
- This ignition switch does NOT require dealer programming or calibration; it is a plug-and-play component, making used OEM parts a great value.
- Before blaming the switch, always check the key fob battery and the car's 12V battery, as these are far more common causes of no-start issues on the RLX.
- A major fuel pump recall affects these models and can cause identical no-start symptoms. Check if your vehicle's VIN is affected before buying parts.
Is It Really Your Ignition Switch?
Before you replace the start/stop button on your 2018-2020 Acura RLX, it's important to know that many starting issues are caused by other, more common problems. A no-start condition is frequently misdiagnosed as a bad ignition switch. Before buying a replacement, check these items first:
- Key Fob Battery: A weak or dead battery in your key fob is a very common reason the car won't detect the key and refuse to start. If you have to press the button multiple times or see a "Key Not Detected" message, try replacing the CR2032 battery in your fob first.
- 12V Vehicle Battery: A weak 12-volt battery is the leading cause of starting problems and strange electrical behavior in the Acura RLX, especially the Sport Hybrid model. A low battery can cause a cascade of warning lights on the dashboard, making it seem like multiple systems have failed when the root cause is simply insufficient voltage. Have your 12V battery tested before suspecting other components.
- Brake Pedal Switch: The vehicle will not start unless the system detects that the brake pedal is depressed. A faulty brake pedal switch can prevent this signal from being sent, leading to a no-start condition.
Variant Differences: Hybrid vs. Non-Hybrid
Warning: The ignition switch for the standard (non-hybrid) RLX and the RLX Sport Hybrid are NOT interchangeable. They have different internal electronics and part numbers. You must match the part to your vehicle's specific powertrain.
Verifying the correct part number is the most important step when buying a replacement switch. Installing the wrong one will result in it not working.
| Vehicle Model | Part Number Family | Known Part Numbers |
|---|---|---|
| 2018-2020 Acura RLX (Standard, FWD) | 35881-TY2-A3x | 35881-TY2-A31, 35881-TY2-A32 |
| 2018-2020 Acura RLX Sport Hybrid (SH-AWD) | 35881-TY3-A2x | 35881-TY3-A21, 35881-TY3-A22 |
The key identifier is the middle part of the part number: TY2 for non-hybrid and TY3 for the Sport Hybrid.
Symptoms of a Failing Ignition Switch
If you have ruled out the battery and key fob, a failing start/stop button may be the cause. Symptoms point specifically to the button itself:
- Engine won't start or shut off: The button does not respond at all when pressed, even with a known good key and vehicle battery.
- Intermittent operation: The vehicle may require multiple presses of the button to start or shut off.
- Button illumination failure: The LED light on the button does not illuminate or flickers, indicating an internal electrical issue with the switch itself.
- Stuck in Accessory Mode: The vehicle will power on to accessory mode but will not proceed to start the engine when the button is pressed again with the brake applied.
Known Issues, Recalls, and TSBs
While there are no recalls specifically for the ignition switch on the 2018-2020 RLX, there are major recalls for other components that can cause a no-start or stalling condition.
Safety Recall: Fuel Pump Failure
A significant recall was issued for a faulty low-pressure fuel pump in many Honda and Acura vehicles, including the 2018-2020 RLX and RLX Sport Hybrid. The fuel pump impeller can swell and cause the pump to fail, which can prevent the engine from starting or cause it to stall while driving. Symptoms include difficulty starting, engine hesitation, and a Check Engine Light with code P0087 (Fuel Rail Pressure Too Low). Before replacing any ignition components for a no-start condition, it is critical to check with an Acura dealer to see if your vehicle is affected by this recall.
Programming and Installation
Pro Tip: The Engine Start/Stop button assembly does not need to be programmed or flashed after installation. It is a simple plug-and-play component. The vehicle's security and immobilizer information is stored in the key fob and the car's smart entry control unit, not the switch itself. This makes a used OEM switch an excellent, cost-effective option.
Replacement Walkthrough
Replacing the switch is a straightforward DIY job that typically takes less than an hour.
- Disconnect the negative terminal of the 12V battery.
- Remove the lower dashboard trim panel beneath the steering wheel. This is usually held in by clips and a few Phillips head screws.
- Carefully lower the panel to gain access to the back of the ignition switch.
- Locate the ignition switch on the dashboard, to the right of the steering column.
- Press the release tab on the electrical connector and unplug it from the back of the switch.
- Depress the retaining tabs holding the switch into the dash panel and push it out from the front.
- Install the new switch by pushing it into place, reconnecting the electrical connector, and re-installing the dash trim.
- Reconnect the battery terminal and test for proper operation.
Buying a Used 2018-2020 RLX Ignition Switch
A used OEM switch is a reliable and budget-friendly alternative to a new part. Since no programming is required, it is a simple swap.
- Verify the Part Number: This is the most important step. Double-check that the part number (especially the TY2 or TY3 code) matches your vehicle's powertrain.
- Inspect the Connector: Ensure the electrical connector pins on the back of the switch are straight and free of corrosion.
- Check the Button Face: Look for a switch with minimal cosmetic wear. The lettering and symbols should be clear and not worn off.
- Source Matters: Purchase from a reputable seller who specifies the vehicle the part came from, including the model (Hybrid or non-hybrid) and mileage.
Replacement Cost Breakdown
The cost to replace the ignition switch can vary, but buying a used part and performing the labor yourself offers significant savings.
| Item | Estimated Cost | Notes |
|---|---|---|
| New OEM Part | $260 - $380 | Price from an Acura dealership or online OEM parts retailer. |
| Used OEM Part | $75 - $150 | Typical price from a reputable automotive recycler or online marketplace. |
| New Aftermarket Part | Not Available | Direct-fit aftermarket replacements for this specific part are not commonly manufactured. |
| Shop Labor | $75 - $150 | Represents 0.5 - 1.0 hours of labor at a typical independent shop rate. |
Frequently Asked Questions (FAQ)
Do I need to take my car to the dealer to program the new ignition switch?
No. The ignition start/stop button does not contain any security information and does not require programming. It is a plug-and-play part. You can install it yourself without needing any special tools or a dealer visit.
Can I use a switch from a non-hybrid RLX in my Sport Hybrid?
No. The switches for the standard and hybrid models are electronically different and not interchangeable. You must use a switch with the correct part number series for your vehicle (TY2 for standard, TY3 for Sport Hybrid).
The button lights up but the car won't start. Is the switch bad?
Not necessarily. If the button is lighting up and changing states (e.g., from off to orange for accessory mode), it is likely sending a signal. The problem is more likely with another part of the starting system, such as a weak 12V battery, a bad starter motor, or a failed fuel pump.
Is it difficult to replace the RLX ignition switch myself?
No, it is considered a relatively easy DIY repair. The process mainly involves removing the lower dash trim panel to access the back of the switch. Basic hand tools are all that is required, and the job can typically be completed in under an hour.
Technical Specifications
OEM Part Numbers: 35881-TY2-A31 35881-TY2-A32 35881-TY3-A21 35881-TY3-A22
Plug-in electronic switch assembly with integrated LED indicator. Functions as an input to the Body Control Module and Smart Power Control Unit.
The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.
- Acura RLX:
- Is It Really Your Ignition Switch?
- Variant Differences: Hybrid vs. Non-Hybrid
- Symptoms of a Failing Ignition Switch
- Known Issues, Recalls, and TSBs
- Safety Recall: Fuel Pump Failure
- Programming and Installation
- Replacement Walkthrough
- Buying a Used 2018-2020 RLX Ignition Switch
- Replacement Cost Breakdown
- Frequently Asked Questions (FAQ)
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