Symptom Chart C (Unwanted ABS Modulation)

Symptom Chart C:

Symptom Chart C Wiring Schematic:

TEST DESCRIPTION
Test numbers refer to circled numbers on the diagnostic chart.

1. Checks if valve activation due to erroneous electrical "noise" induced onto wheel speed sensor circuits.

2. The wheel speed sensor output should gradually increase with vehicle speed. There should be no skips or jumps. All four wheel speed sensor outputs should be identical. On a slow down, one of the signals may drop off faster than the others, indicating a lock-up condition or a problem with the speed sensor or wiring (corrosion etc.).