Toyota Headlight Bulbs Messing With ABS
Some 2014-2020 Toyota 4Runner vehicles may experience the ABS light on, with DTC C0226, C0236, C0246 and C0256 stored currently in the ABS system.
Inspect the ABS connector for signs of damage. If OK, go to Step 2.
Use a Picoscope to monitor the ground to the skid control ECU with the engine running and headlights on. Then, with the headlights off, if the ground circuit voltage fluctuates with the headlights on compared to off, go to Step 3.
Inspect the headlight bulbs for any aftermarket parts, such as LED or HID bulbs. If aftermarket bulbs are found, perform the same test with factory headlight bulbs.
Example of skid control ground not fluctuating with headlights off.
Inspect the aftermarket headlight bulbs. If aftermarket bulbs are found, repeat the test with factory bulbs to see if this corrects the issue.