Does your trac light come on or both abs and trac? What maybe happening if the sensors are not tightend down is the magnet (sensor) will shift upward on a bump and weaken amplitude and signal frequency their for shutting down the system. Damaged or missing teeth on the sensor ring will show up as flat spots or gaps in the sine wave pattern aswell. A bent axle or hub will produce an undulating pattern that changes as the strength of the sensor signal changes with every revolution. In your cases it indicates a weak signal caused by an excessively wide air gap between the tip of the sensor and its ring, or a build up of metallic debris on the end of the sensor. A weak signal can also be caused by internal resistance in the sensor or its wiring circuit, or loose or corroded wiring connectors. Clean the sesnsors of mettallic debris they are right behind the discs , held down by a single 10mm bolt. Use a deep socket prefrebly. Once you remove it clean the tip , inspect the splines with a flash light , you can add some grease to stop any corrosion or buildup on the tip. After you cleaned and tightened all 4 sensors take a drive , get her on some bumps. If the system fails again Dont restart the car , just leave it running if you can , now get into the diagnostic box , remove the grey short pin and connect trerminals Tc and E1. Look at your ABS lamp and write down the code its throwing. First series of blinks is first digit second series is second digit 2.5 second gap is your second code if their is any , if not it keeps repeation the fist code.
TOYOTA ABS CODES
11 — Open shorted relay circuit. Check modulator wiring harness, solenoid relay, solenoid relay wiring harness and solenoid relay connector.
12 — Short in solenoid relay circuit. Check modulator wiring harness, solenoid relay, solenoid relay wiring harness and solenoid relay connector.
13 — Open pump motor relay circuit. Check modulator wiring harness, pump motor wiring harness, pump motor relay circuit and pump motor connector.
14 — Short in pump motor relay circuit. Check modulator wiring harness, pump motor wiring harness, pump motor relay circuit and pump motor connector.
21 — Open or short in ABS solenoid for right front wheel.
22 — Open or short in ABS solenoid for left front wheel.
23 — Open or short in ABS solenoid for right rear wheel.
24 — Open or short in ABS solenoid for left rear wheel.
31 — Problem in right front wheel speed sensor circuit.
32 — Problem in left front wheel speed sensor circuit.
33 — Problem in right rear wheel speed sensor circuit.
34 — Problem in left rear wheel speed sensor circuit.
35 — Open in left front or right rear wheel speed sensor (WSS) circuit.
36 — Open in right front or left rear WSS circuit.
37 — Faulty rear speed sensor rotor.
41 — Battery voltage too low or high (under 9.5 volts or over 16.2 volts). Check battery and charging system.
51 — Pump motor is locked or pump motor circuit is open. Check pump motor, motor relay, wiring harness and modulator ground connections.
"Always on" (no flash codes, just a steady light) — Malfunction of ABS module
If you get a speed sensor code you need to check that the harnesses are connected properly , the front harnesses are in the engine bay sticking out of the ABS relay , they are grey in color, slide the relay off the bracket and check they are plugged in snug , the rears have the wires coming out under the plastic speaker box behind your rear seat , they them go under the plastic panals and have a harness (grey) right on there , you will see it once you take off the plastic interior panals on both sides. If this still does not solve your problem i can give you s advanced wheel speed sensor check method , and some more ways you can test the entire system along with diagrams. BTW i fixed my ABS system yesterday , turned out to be the harnesses behind the rear interior panals. When i was installing my Speakers and crossovers my Helper mistook it for speaker wire ROTFL :blah: Good luck