Speed Sensor Diagnostics

NOTE: While diagnosing speed sensors, brake system functions as a conventional system.

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.

NOTE: If ABS warning light does not flash, check ABS warning light circuit and Ts circuit. See ABS WARNING LIGHT and Ts TERMINAL CIRCUIT .

Turn ignition off. Connect jumper wire between terminals Ts and E₁ of DLC1. See Figure. Set parking brake. Start engine. ABS warning light should flash 4 times per second.
Shift transfer case to L4 position. Engage center differential lock switch to ON position. Drive vehicle straight ahead at about 28 MPH for several seconds. ABS warning light should go off.
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 warning 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.
If 2 or more DTCs are stored, there will be a 2.5-second pause between each DTC. After all DTCs are flashed, there will be a 4-second pause, then all DTCs will repeat.
Record DTC. Turn ignition off. Repair as necessary. See SPEED SENSOR DTC table. Remove jumper wire from DLC1. Clear DTC. See CLEARING DIAGNOSTIC TROUBLE CODES .

SPEED SENSOR DTC

DTC	Possible Cause
71	Low Output Voltage Of Right Front Speed Sensor
72	Low Output Voltage Of Left Front Speed Sensor
73	Low Output Voltage Of Right Rear Speed Sensor
74	Low Output Voltage Of Left Rear Speed Sensor
75	Abnormal Change In Output Of Right Front Speed Sensor
76	Abnormal Change In Output Of Left Front Speed Sensor
77	Abnormal Change In Output Of Right Rear Speed Sensor
78	Abnormal Change In Output Of Left Rear Speed Sensor
79	Faulty Deceleration Sensor
81	Faulty Master Cylinder Pressure Sensor Output Signal
82	Transfer Indicator (Center Differential Lock) Switch Malfunction
83	Transfer L4 Position Switch Malfunction