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Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.

The New Hotness

  • Toyota Sienna: ABS Trouble Codes

    The Sienna lit up the tire pressure warning light and the ABS trouble light on the trip from Rochester. The pressures were OK, if a bit low, but the early Toyota TPMS used wheel rotation sensors rather than direct pressure sensors, and we suspect a sensor went bad.

    The ABS doesn’t report errors through the OBD II interface, requiring a jumper between TC and E1 in the ABS diagnostic interface block under the hood. Our Larval Engineer shows much respect for the engineer who included the pin ID layout under the flip-top lid, eliminating the need for scratch paper.

    Despite diligent searching, there seems to be no Official Documentation of the blink codes appearing on the ABS trouble indicator. Fragmentary evidence suggests that a table applying to a Toyota MR2 MKII sports car would be generally applicable, which is hereby ripped to forestall link rot:

    Code Number Diagnosis
    11 open circuit in solenoid relay circuit
    12 short circuit in solenoid relay circuit
    13 open circuit in pump motor relay circuit
    14 short circuit in pump motor relay circuit
    21 open or short circuit in 3 position solenoid of front right wheel
    22 open or short circuit in 3 position solenoid of front left wheel
    23 open or short circuit in 3 position solenoid of rear wheels
    31 front right wheel speed sensor signal malfunction
    32 front left wheel speed sensor signal malfunction
    33 rear right wheel speed sensor signal malfunction
    34 rear left wheel speed sensor signal malfunction
    35 open circuit in front left or rear right wheel speed sensor
    36 open circuit in front right or rear left wheel speed sensor
    41 abnormal battery voltage ( < 9.5 or > 17 )
    51 pump motor of actuator locked or open circuit in pump motor circuit in actuator
    ALWAYS ON computer malfunction

    The  3-4 blink code indicates a left rear wheel sensor failure. Such sensors (or their cables) seem to be either $35 or $175 from the usual sources, with no indication of why some are far more expensive than others. The pictures and descriptions are unhelpful, to say the least.

    We’ll try cleaning the sensor, which probably won’t improve the situation, and then replace the poor thing.