Hydraulic Modulator Testing

CAUTION: Do not repair hydraulic modulator except for replacing relays. If hydraulic modulator is defective it must be replaced.

Hydraulic modulator, high and low pressure testing

- remove one front wheel
- remove bleeder screw from caliper





- connect VW 1310 and bleed
- press brake pedal until pressure gauge reads 50.0 bar (725.0 psi)
- If pressure drops more than 4.0 bar (58.0 psi) in 45 seconds, replace hydraulic modulator
- press brake pedal until pressure gauge reads 6.0 bar (87.0 psi)
- If pressure drops more than 1.0 bar (14.5 psi) in 3 minutes,
- replace hydraulic modulator