The following procedures require driving the vehicle while it is in the diagnostic mode. The anti-lock system will be disabled; only normal braking function will be available.
- If working on a 4WD vehicle, make certain it is only in 2WD. Check the battery voltage with the engine off; voltage should be approximately 12 volts.
- With the ignition switch ON , make certain the REAR ANTI-LOCK warning lamp comes on for about 3 seconds and then goes out. Turn the ignition switch OFF .
- Using a 3-way jumper, connect terminals Tc, Ts and E1 at the Data Link Connector (DLC1).
- Pull the parking brake on securely and start the engine without stepping on the brake pedal. Depressing the brake pedal will either void the test or cause the system to enter a different diagnostic mode.
- The dashboard warning lamp should flash evenly about 4 times per second. If, instead, a code is flashed, repairs must be made and the code(s) cleared before continuing. If the light does not flash, check the parking brake switch, the DLC1 connector and the wiring to the ABS controller.
- To check the sensor signal level, release the parking brake and drive the vehicle straight ahead at low speed. Once a speed of 2.5-3.7 mph (4-6 km) is reached, the warning lamp should turn off. Once the light has gone off, it should begin to blink as the vehicle leaves the speed range. This blinking is normal and indicates the speed sensor is operating correctly. If no blinking occurs, the system is defective.
- Check the sensor signal change by driving the vehicle on the road. Once a speed of 25-31 mph (40-50 km) is achieved, the warning lamp should come on after a one second pause. As before, the lamp should blink evenly as the vehicle leaves the speed range; failure to blink indicates a system fault.
While the warning lamp is off, do not subject the vehicle to any shocks or impact such as shifting, acceleration, deceleration or road impact.
- Stop the vehicle in a safe location and apply the parking brake fully. Read and record any stored codes which are displayed.
- Turn the ignition switch OFF ; remove the jumper wire from the DLC1 connector.
See Figures 1, 2 and 3
- Check the installation of the sensor. If the mounting bolt is loose, tighten it to 14 ft. lbs. (19 Nm).
- Disconnect the speed sensor harness from the ABS harness.
- Measure the resistance with an ohmmeter between the terminals of the sensor connector. Correct resistance is 580-700 ohms. If the resistance is outside the specification, the sensor must be replaced.
- Check that there is no continuity between each sensor terminal and the sensor body. If any continuity is found, the sensor is faulty.
- Reconnect the speed sensor to the harness.
REMOVAL & INSTALLATION
See Figure 4
The speed sensor is located in the rear differential housing. It transmits a small electrical signal to the ECU based on the rotational speed of the differential ring gear.
- Unplug the sensor cable connector from the harness. If the sensor cable is held by brackets or clamps, release them.
- Remove the retaining bolt holding the sensor to the differential.
- Remove the sensor straight out of its mount. Protect the tip from impact or abrasion.
- Install the sensor, making certain it is firmly seated and not crooked in its mount.
- Tighten the retaining bolt to 14 ft. lbs. (19 Nm).
- Reinstall any mounting clips or brackets for the sensor cable, then attach the cable to the ABS harness.
- Double check the cable routing; it must be completely clear of any moving components.