Diagnostic Aids

Ensure following conditions have not or do not exist prior to performing this test:

Individual wheel diameter too large.
Dynamic wheel balancing was performed with ignition on.
Vehicle was towed on rear wheel with ignition on.
With vehicle on hoist, one wheel was turned with ignition on.

Check Wheel Sensor Output

Ensure all wheels turn freely. Ensure parking brake is operating properly and is not dragging on one wheel. Turn ignition off. Partially raise vehicle on hoist. Using New Generation Star (NGS) (007-00500) tester, select PID/DATA MONITOR and RECORD. Select suspect wheel and press TRIGGER. Rotate suspect wheel by hand and observe NGS display screen. If display indicates wheel speed, go to step 4). If display does not indicate wheel speed, go to next step.

Check Wheel Sensor Resistance

Disconnect ABS control module 22-pin connector and Hydraulic Control Unit (HCU) 8-pin connector. See COMPONENT LOCATIONS . Connect Breakout Box (007-00033) and Adapter (007-00115) to ABS control module connector, leaving HCU disconnected. Measure resistance of suspect wheel speed sensor between indicated breakout box test pins. See CHECKING WHEEL SPEED SENSOR RESISTANCE table. Move, flex, tap and shake connector and wiring harness while testing. If resistance is 1000-1500 ohms, go to next step. If resistance is not 1000-1500 ohms, go to step 4).

CHECKING WHEEL SPEED SENSOR RESISTANCE

Application	Breakout Box Test Pins
Left Front Wheel Sensor	3 & 10
Left Rear Wheel Sensor	8 & 16
Right Front Wheel Sensor	1 & 9
Right Rear Wheel Sensor	2 & 17

Check Sensor Indicators & Wheel Speed Sensors

Raise vehicle on hoist. Check front and rear toothed sensor indicators for missing teeth or loose/missing ring. Check front and rear wheel speed sensors for correct installation. Replace components as necessary and repeat step 1). If no problems are found, replace suspect wheel speed sensor. After repair is completed, clear codes.

Check Wheel Speed Sensor Wiring

Disconnect front or rear suspect wheel speed sensor connector. Measure resistance of suspect wheel speed sensor between indicated breakout box test pins. See CHECKING WHEEL SPEED SENSOR RESISTANCE table. If resistance is 100,000 or less, go to next step. If resistance is more than 100,000 ohms, replace wheel speed sensor. After repair is completed, clear codes and retest system.

Check For Open Wheel Speed Sensor

Disconnect front or rear suspect wheel speed sensor connector. Measure resistance between each terminal of suspect wheel speed sensor connector and appropriate test pin at breakout box. See CHECKING WHEEL SPEED SENSOR CIRCUITS table. If resistance is 5 ohms or less, go to next step. If resistance is more than 5 ohms, repair open suspect circuit. Reconnect all components. Clear codes and retest system.

CHECKING WHEEL SPEED SENSOR CIRCUITS

Application & Wire Color		Breakout Box Test Pin
Left Front Wheel Sensor
White		3
Brown		10
Left Rear Wheel Sensor
White/Blue		8
Brown/Blue		16
Right Front Wheel Sensor
White/Red		1
Brown/Red		9
Right Rear Wheel Sensor
White/Green		2
Brown/Green		17

Check For Short To Ground

Disconnect front or rear suspect wheel speed sensor connector. Measure resistance between breakout box test pin No. 5 (ground) and indicated test pins for suspect wheel speed sensor circuit. See CHECKING WHEEL SPEED SENSOR CIRCUITS table. If each resistance is more than 10,000, replace Hydraulic Control Unit (HCU). If any resistance is less than 10,000 ohms, repair short to ground in suspect sensor circuit. Reconnect all components. Clear codes and retest system.