Automated Modulator Test

AUTOMATED MODULATOR TEST
Tools Required
Scan Tool
If a mechanical modulator malfunction is suspected, rough ABS performance is reported, or if any modulator service has been performed, the automated modulator test must be performed to verify the repair has corrected the identified problem and the displacement cylinder pistons are returned to their top-most (home) position. The scan tool will prompt you for replies to changes in the brake pedal position. These brake pedal position changes are a result of modulator component control in a specific order that allows component malfunctions to be determined. It is very important, especially when testing the rear channel, that each reply to the scan tool questions be carefully considered. During rear channel testing, pedal movement will be felt as a bump, which is much different from the movement felt in the front channels. The pedal movement for the front brakes should be smoothly downward toward the floor on "release" or smoothly upward toward the top of the pedal travel on "apply."