24
Troubleshooting and Testing
4.8
Voltage Check
4.8.1
Test Equipment: Volt-Ohm Meter (VOM)
Use of a VOM with automatic polarity sensing is recommended. This eliminates the concern of the polarity
of the meter leads during voltage measurements.
4.8.2
ECU Voltage, Ground and Load Check
Voltage must be between 9.5 and 14 volts for the 12-volt hydraulic ABS to function correctly.
Check the ECU voltage, ground and load as follows:
1. Disconnect the harness connected to the ECU.
2. Turn the ignition ON.
3.
Check for battery voltage across the following pins:
Pins 1 to 47
Pins 32 to 47
Pins 8 to 47
4.
Check for correct ground:
Verify that the resistance between pin 47 and chassis ground is less than 1 ohm.
5. Perform load (impedance) test.
Contact the WABCO Customer Care Center at 855-228-3203 for simple ways to perform load tests.
4.8.3
Sensor Output Voltage Check
Sensor output voltage must be at least 0.2 volt AC at 30 rpm. Test the sensor output voltage as follows:
1. Turn the ignition OFF.
2. Disconnect the ECU harness so that the voltage at the pins in it can be measured.
3. Place blocks under the front and rear tires to stop the vehicle from moving.
4.
Raise the vehicle off the ground. Place safety stands under the axle.
5.
Rotate the wheel by hand at 30 rpm (1/2 revolution per second).
6. Measure the voltage at the pins indicated in Table A. Voltage tolerance is >0.2 volts alternating current
(VAC).
