Diagnosis & Testing: Pre-Inspection

To correctly diagnose system, inspect all brake components for wear or damage. Ensure hydraulic system is full and no leaks exist. Ensure brake booster is functioning properly. Check air gap at each speed sensor. See WHEEL SPEED SENSOR AIR GAP TABLE.
On 240SX, measure rear speed sensor air gap by inserting feeler gauge between sensor mating face on differential to exciter ring on pinion flange. Measure speed sensor pole piece from sensor mating face to pole piece tip. Subtract sensor measurement from differential measurement to obtain air gap.
On all models, if air gap exceeds specification, replace speed sensor, pinion flange (240SX) or wheel hub assembly. Inspect rotor teeth. Replace rotor (and companion flange, if necessary) if teeth are damaged. Go to PRELIMINARY CHECK.

WHEEL SPEED SENSOR AIR GAP