Procedures

OOOO. Hydraulic modulator, replacement

Note! Do not open the master cylinder under any circumstances. It takes special equipment and facilities to reassemble.

[OOOO1]

Preparations

- Ignition off
- Put rags under the hydraulic unit to protect painted surfaces against brake fluid spillage.
- Depress brake pedal a few times so there is no vacuum left in the brake servo.
- Clean connections to brake pipe on hydraulic unit and master cylinder.
- Disconnect sparkplug leads from coil and mountings on air filter casing.
- Remove air filter casing with inlet pipe and hose to air heater.

[OOOO2]

In cars with turbo

Remove:






- Intake pipe between filter casing and turbo unit

[OOOO3]

Locking brake pedal in position

- Jack car up
- Remove cap from bleed nipple by LH front wheel.
- Connect hose from drain bottle.
- Open bleed nipple, depress brake pedal and hold it down or lock it in that position.
- Close bleed nipple.

[OOOO4]

Removing bracket and hydraulic unit

Remove:

- Brake pipe between hydraulic unit and master cylinder.
- Undo brake pipe to wheel brakes.

Seal off the brake pipe and connections on the hydraulic unit and master cylinder to prevent dirt getting into the system.

- Undo the connection to the control module by first pressing in the catches on the back of the cover (facing wheel housing). Then carefully turn the cover upwards to release the catches.

Remove:

- Bracket mounting bolts and lift bracket up.
- Lift bracket up and undo vacuum hose.

[OOOO5]

In cars with TRACS:






- Lift bracket up slightly and move it forward.
- Disconnect non-return valve and vacuum hose from brake servo.

[OOOO6]

Removing hydraulic unit from bracket






Note! Hydraulic unit must be replaced as a complete unit. Hydraulic unit must not be opened under any circumstances. Special equipment and facilities are needed to re-assemble it.

- Disconnect pump motor connection from control module.
- Remove bracket and control module from hydraulic unit.

[OOOO7]

Checking hydraulic unit

Check that the hydraulic unit is of the correct type, depending on whether the car is fitted with TRACS. The difference is that the TRACS hydraulic unit has seven valves between it and the control module instead of six.

Note! The hydraulic unit must not be opened under any circumstances. Special equipment is needed for re-assembly.

[OOOO8]

Installing hydraulic unit






Note! The hydraulic unit is full of brake fluid. It is important not to remove the protective plugs until the brake pipe is connected.

Check and install the control module to the hydraulic unit as per MMMM. Control module, replacement. [1][2]Procedures Install bolts. Tighten to 1.8 Nm.

- Install the new hydraulic unit on the bracket and tighten the mounting bolts. Tighten to 8 Nm.
- Hold down the vacuum hose and install bracket carefully.
- Connect pump motor connector to control module.
- Tighten mounting bolts to 8 Nm.

[OOOO9]

In cars with TRACS






Insert vacuum hose between bracket and hydraulic unit. Check that non-return valve and rubber seals are intact and in good condition. Connect non-return valve to brake servo.

[OOOO10]

Installing hydraulic unit continued

- Connect connector to control module and pump motor.
- Remove protective plugs and connect brake pipe to hydraulic unit and master cylinder. Tighten to 14 Nm (10.3 ft lb).
- Release brake pedal.
- Install air filter casing with inlet pipe and hose to air heater.
- Connect sparkplug leads to coil.

[OOOO11]

In cars with turbo

Install:

- Intake pipe between air filter casing and turbo.

[OOOO12]

Finishing work

- Bleed braking system as per AAAA. Bleeding brakes with bleeding unit. Service and Repair

Clean up any brake fluid spillage with lukewarm water and car-wash shampoo.

[OOOO13]

Function check






- Read out any DTCs which are posted in the control module and replace them.
- Switch off Volvo ST. Check that ABS warning light stops flashing.
- Test drive the car, check that brakes are working and that ABS warning light stops flashing.

Warning! The ABS and EBD systems are not available while Volvo Diagnostics is activated. Take great care when test driving as there is a serious risk of the wheels locking.