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Home >> Lexus >> 1998 >> LX 470 >> Repair and Diagnosis >> Brakes >> Traction Control >> Anti-Lock Brake System >> Diagnosis & Testing >> Speed Sensor Diagnostics

Speed Sensor Diagnostics

NOTE: While diagnosing speed sensors, brake system functions as a conventional system.
  1. Ensure battery is in good condition and is fully charged. Turn ignition on. ABS light should illuminate, then go out after about 3 seconds. If ABS light does not illuminate, check fuse, bulb, and wiring harness.
  2. Turn ignition off. Connect jumper wire between terminals Ts and E1 of DLC1. See Figure. Set parking brake. Start engine. ABS light should flash 4 times per second.
  3. Shift transfer case to L4 position. Engage center differential lock switch to ON position. Drive vehicle straight ahead above 28 MPH for several seconds. ABS light should go off.
  4. Stop vehicle. Connect jumper wire between terminals Tc and E1 of DLC1, leaving terminals Ts and E1 connected. If a DTC is stored, 4 seconds will elapse, then ABS light will begin to flash a 2-digit DTC. First group of flashes will indicate first digit in DTC. After a 1.5-second pause, second group of flashes will indicate second digit in a DTC.
  5. If 2 or more DTC are stored, there will be a 2.5-second pause between each DTC. After all DTC are flashed, there will be a 4-second pause, then all DTC will repeat.
  6. Record DTC. Turn ignition off. Repair as necessary. See SPEED SENSOR DTC . Remove jumper wire from DLC1. Clear DTC. See CLEARING DTC .
SPEED SENSOR DTC

DTC Possible Cause
71 Right Front Speed Sensor Signal Low Voltage
72 Left Front Speed Sensor Signal Low Voltage
73 Right Rear Speed Sensor Signal Low Voltage
74 Low Voltage Of Left Rear Speed Sensor Signal
75 Right Front Speed Sensor Abnormal Signal
76 Left Front Speed Sensor Abnormal Signal
77 Right Rear Speed Sensor Abnormal Signal
78 Left Rear Speed Sensor Abnormal Signal
79 Faulty Deceleration Sensor
82 Center Differential Lock Position Switch Malfunction
83 L4 Position Switch Malfunction