C0226 on 2014-2020 Toyota 4Runner: ABS Light Causes and Fixes

What's Unique About the 2014-2020 Toyota 4RUNNER

The 5th generation 4Runner is uniquely sensitive to electrical interference. Toyota issued a Technical Service Bulletin (TSB T-TT-0597-20) because aftermarket LED and HID headlight bulbs can create significant radio frequency interference (RFI). This RFI introduces electrical 'noise' onto the ground circuit for the Skid Control ECU (the ABS module). This interference causes the module to incorrectly report internal solenoid failures, setting codes C0226, C0236, C0246, and C0256 simultaneously. The issue is not the bulbs themselves drawing too much power, but the electronic drivers or ballasts creating electromagnetic fields that disrupt sensitive electronics.

Diagnostic Flowchart

Tap your situation to follow the diagnostic path that matches what you're seeing on this vehicle.

Symptoms You May Notice

• ABS warning light is on
• Traction Control (TRAC) warning light is on
• Vehicle Stability Control (VSC) warning light may be on
• A continuous or intermittent beeping/alarm from the dashboard may occur.
• Loss of ABS functionality (wheels may lock up under hard braking)
• Loss of traction and stability control
• Cruise control may be disabled

Most Likely Causes

1. Aftermarket LED or HID Headlight Bulbs 🔴 High Probability As documented in Toyota TSB T-TT-0597-20, the Skid Control ECU's grounding is sensitive to Radio Frequency Interference (RFI) generated by the power supplies (ballasts or drivers) of many aftermarket bulbs. The halogen headlight housings are not designed to shield the RFI produced by these electronics.
   How to confirm: Turn the headlights OFF. Clear the trouble codes using a scan tool. Drive the vehicle to see if the codes return. If the codes only appear when the headlights are ON, the aftermarket bulbs are the cause. The TSB outlines using an oscilloscope to monitor the ground circuit voltage, which will show fluctuations when the headlights are on if RFI is the cause.
   Typical fix: Remove the aftermarket LED/HID bulbs and replace them with standard OEM-style halogen bulbs. 🎬 See how a simple $30 bulb swap can clear your VSC lights. Ensure the headlight housing dust covers are properly installed and have not been modified or drilled, as this can worsen interference.
   Est. part cost: $20-$60
2. Failed ABS Actuator Assembly ⚪ Low Probability If aftermarket lights are not the cause, the codes indicate a genuine internal failure of the solenoid circuits within the sealed ABS actuator unit. This can be due to an internal fluid leak or an electronic failure on the module's circuit board.
   How to confirm: This is the diagnosis by exclusion. If the vehicle has factory halogen bulbs (or the issue persists after swapping back to them), and all power and ground connections to the module are verified as good, the module itself is condemned. A technician can also measure the resistance across the valve solenoid coil terminals on the actuator; readings outside the specified range indicate a failure.
   Typical fix: Replace the entire ABS actuator assembly (also called the ABS pump and module). The new unit will require a 'Zero Point Calibration' and brake system bleeding using a diagnostic scan tool.
   Est. part cost: $700-$1800

Rare But Worth Checking

• Poor Ground Connection for Skid Control ECU:

Diagnosis Steps

1. Check the vehicle for any aftermarket headlight bulbs (LED or HID). Many owners may not realize they were installed by a previous owner.
2. Inspect the headlight dust covers. Ensure they are present and have not been drilled or modified, which can allow RFI to escape.
3. If aftermarket bulbs are found, replace them with standard halogen bulbs (Low Beam: H11, High Beam: 9005). Clear the codes and re-test.
4. If no aftermarket bulbs are present, or if the problem persists, use a scan tool to clear the codes.
5. Turn the headlights ON and start the engine. Drive the vehicle above 15 mph. Note if the ABS light returns.
6. Turn the headlights OFF. Clear the codes again and drive the vehicle. If the light does not return with the headlights off, this confirms RFI from the lighting system is the cause.
7. If the codes return regardless of headlight position, inspect the wiring connector and ground points for the Skid Control ECU for any damage or corrosion. Per TSB T-TT-0597-20, the ground pins are Pin 1 (GND1) and Pin 32 (GND2) on the 'A' connector for models with a hydraulic booster, or Pin 1 (GND1) and Pin 13 (GND2) for models with a vacuum booster.
8. If wiring and grounds are confirmed good, the ABS actuator assembly has likely failed 🎬 Watch: This walkthrough shows how to diagnose and fix these ABS lights. and requires replacement. This should be confirmed by a professional.

Parts You'll Likely Need

• Halogen Headlight Bulbs (Low Beam) (OEM #90981-13075) — This is the most common fix, needed to resolve electrical interference from aftermarket LED/HID bulbs as per TSB T-TT-0597-20. The low beam is type H11.
  Trusted brands: Philips, Sylvania, Wagner
  OEM price range: $20-$25 (each)
  Aftermarket price range: $10-$20 (each)
• Halogen Headlight Bulbs (High Beam) (OEM #90981-13046) — To fully revert to stock, the high beams may also need to be replaced. The high beam is type 9005.
  Trusted brands: Philips, Sylvania, Wagner
  OEM price range: $5-$20 (each)
  Aftermarket price range: $5-$15 (each)
• ABS Actuator Assembly (OEM #47070-60050) — If aftermarket lights are not the cause, the actuator has an internal fault and must be replaced as a complete unit.
  Trusted brands: Toyota (OEM)
  OEM price range: $720-$1800
  Aftermarket price range: $600-$900 (Remanufactured/Used)

Related Codes That Often Appear With This One

• C0236 — This is the fault code for another solenoid circuit within the same ABS actuator. They typically appear together as a set of four.
• C0246 — This is the fault code for a third solenoid circuit within the same ABS actuator. They typically appear together as a set of four.
• C0256 — This is the fault code for the fourth solenoid circuit within the same ABS actuator. They typically appear together as a set of four.

Technical Service Bulletins (TSBs) & Recalls

• T-TT-0597-20: Addresses an ABS Light ON condition with DTCs C0226, C0236, C0246, and C0256. It explicitly recommends inspecting for aftermarket LED or HID headlight bulbs causing radio frequency interference (RFI) on the Skid Control ECU ground circuit. It also provides specific ECU pinouts for ground circuit testing.

Platform-Specific Known Issues

• Toyota Technical Service Bulletin T-TT-0597-20 was issued specifically for the 2014-2020 4Runner to address codes C0226, C0236, C0246, and C0256 being caused by aftermarket headlight installations.
• Owners on forums like T4R.org and Reddit have confirmed this exact scenario. One user on T4R.org reported the ABS/TRAC lights illuminating immediately after installing LED low beams, and the lights extinguished after reinstalling the factory halogen bulbs.

Mechanic-Grade Diagnostic Values

• Skid Control ECU Power Supply Voltage — expected: 10 to 14 V. Failure: Voltage below 10V or above 14V indicates a power supply issue to the module.
• Skid Control ECU Ground Circuit Resistance — expected: Below 1 Ω. Failure: Resistance above 1 Ω indicates a poor ground connection, which can cause erratic behavior.
• ABS Actuator Solenoid Resistance (example values) — expected: Holding Solenoids (SFRH, SFLH, etc.): 4.75 - 5.25 Ω; Releasing Solenoids (SFRR, SFLR, etc.): 2.00 - 2.40 Ω. Failure: Readings outside of these ranges suggest an internal failure of the solenoid coil within the actuator.

Scan Tool Commands That Help

• Toyota Techstream: Active Test: ABS Solenoid — After ruling out the headlight RFI issue, a technician can use this function to individually command each solenoid in the ABS actuator to turn on and off. This helps verify if the module is receiving the command and if the solenoid is responding, which can help isolate a true internal actuator failure.
• Toyota Techstream: Utility: Reset Memory — This function is used to clear the zero point calibration data from the Skid Control ECU before performing a new calibration. This is a required first step.
• Toyota Techstream: Utility: Test Mode (Zero Point Calibration) — After replacing the ABS actuator assembly or other related VSC components, this function must be used to calibrate the yaw rate and acceleration sensor. The vehicle must be on a level surface.

Wiring & Ground Locations

• A Connector (Skid Control ECU) — On the ABS Actuator / Skid Control ECU assembly in the engine bay.. This is the main connector where power, ground, and communication lines connect. TSB T-TT-0597-20 specifies which pins to test here.
• Pin A-1 (GND1/GND2) — On the 'A' connector of the Skid Control ECU.. This is a primary ground pin for the ECU. On models with a hydraulic booster, it's GND1. On models with a vacuum booster, it's also GND1. It must have less than 1 Ω resistance to chassis ground.
• Pin A-32 (GND2) — On the 'A' connector of the Skid Control ECU (Hydraulic Booster models only).. This is the second ground pin for the ECU on models equipped with the hydraulic brake booster. It is susceptible to the RFI noise from aftermarket headlights.
• Pin A-13 (GND2) — On the 'A' connector of the Skid Control ECU (Vacuum Booster models only).. This is the second ground pin for the ECU on models equipped with the vacuum brake booster. It is susceptible to the RFI noise from aftermarket headlights.

Real Owner Repair Stories

• ScannerDanner Forum (2006 Toyota Sienna (similar ABS system design)) — ABS and Brake lights were on. Initially intermittent, then became constant. Codes C0226 and C0256 were present.
  ❌ Tried (didn't work) The user first suspected wiring issues but reasoned that since power and ground are shared by multiple solenoids, a wiring fault would likely affect all of them, not just two.
  ✅ What actually fixed it The owner purchased a used ABS module from eBay, installed it, and performed a Zero Point Calibration. This resolved the issue, and the codes did not return after several drive cycles.

OEM Part Supersession History

• 47070-60030 → 47070-60050 — Part revision or update by the manufacturer.
  Heads up: 47070-60050 is the direct replacement for 47070-60030 for applicable models.

Model Year Variations Within This Range

• 2014-2020: Within this year range, 4Runners were equipped with either a hydraulic brake booster or a vacuum brake booster. This changes the pinout for the second ground wire on the Skid Control ECU. For hydraulic boosters, the grounds are pins 1 and 32. For vacuum boosters, the grounds are pins 1 and 13. This is critical for correct diagnosis per TSB T-TT-0597-20.