Hydraulic Modulator

WARNING: This page is about a different car, the 1989 Volvo 760 and 1989 Volvo 740. However, it is still accessible from the selected car via links, so may be relevant.

Modulator pressure control solenoids are mounted inside hydraulic modulator and are not individually serviceable. Modulator assembly must be replaced if solenoids are defective.

1) Turn ignition off. Connect DVOM between terminal No. 32 and terminals No. 2 (left front control solenoid). Then, connect DVOM between terminal No. 18 (rear control solenoid) and 35 (right front control solenoid). Resistance readings should be .7-1.7 ohms.

2) If readings are not within specifications, unplug modulator connector and test resistance from hydraulic modulator terminal No. 4 (ground) of modulator to terminals No. 1, 3 and 5. If readings are not within specifications, repair ECU wiring harness to modulator. If readings are still not within specifications, replace hydraulic modulator.