Vacuum Brake Booster Replacement (W/RPO Code M43, M86)

Vacuum Brake Booster Replacement (w/RPO M43, M86)

Caution: Refer to Brake Fluid Irritant Caution in Service Precautions.

Notice: Refer to Brake Fluid Effects on Paint and Electrical Components Notice in Service Precautions.

Removal Procedure
1. Disconnect the negative battery cable.
2. Remove the cover from the underhood electrical center.





3. Pull back on the connector position assurance (CPA) tab of the electrical connector, then disconnect the connector from the brake fluid level sensor.





4. Remove the underhood electrical center bracket from the vehicle and reposition the electrical center (1) to access the brake master cylinder and brake booster.





5. Remove the brake master cylinder auxiliary reservoir.
6. Release the brake master cylinder pipes from the 6-position pipe clip along the frame rail.
7. Remove the master cylinder mounting nuts.
8. Remove the master cylinder from the vacuum brake booster. Carefully reposition the master cylinder up and outboard, with the brake pipes still attached. Secure the master cylinder in position.





9. Inspect the master cylinder-to-vacuum brake booster seal (1) for damage. Replace the seal (1) if necessary.





10. Disconnect the vacuum check valve (1) from the brake booster and position aside the check valve (1) and vacuum hose (3).
11. Remove the accelerator pedal mounting nuts. Reposition the accelerator pedal to improve tool access to the LH, lower booster mounting nut.
12. Loosen the brake booster mounting nuts.





13. Remove the retaining clip (1) and washer (2) from the brake pedal.
14. Release the brake booster pushrod (3) from the brake pedal.





15. Remove the brake booster mounting nuts.
16. Remove the brake booster and the booster mounting gasket from the vehicle.
17. Inspect the mounting gasket for damage and replace if necessary.

Installation Procedure

Notice: Internal components of this booster are not serviceable. The housing must not be unstaked and separated. Separating the housing will cause permanent deformation, preventing the booster from holding proper volume.

1. Install the mounting gasket to the vacuum brake booster.





2. Install the brake booster to the dash panel.
3. Loosely install the brake booster mounting nuts.





4. Apply a thin coating of lithium grease to the pushrod pin on the brake pedal.
5. Connect the brake booster pushrod (3) to the brake pedal.
6. Install the washer (2) and retaining clip (1) to the brake pedal.

7. Notice: Refer to Fastener Notice in Service Precautions.

Tighten the vacuum brake booster mounting nuts.
^ Tighten the nuts to 25 Nm (18 ft. lbs.).
8. Install the accelerator pedal into position and install the pedal mounting nuts.





9. Important: A small amount of denatured alcohol can be used as an assembly aid when installing the vacuum check valve. Do NOT use soap.
Connect the vacuum check valve (1) with hose (3) to the brake booster.





10. Check to ensure that the master cylinder-to-vacuum brake booster seal (1) is properly seated into the recessed groove on the master cylinder.





11. Install the master cylinder with the brake pipes, to the vacuum brake booster.

12. Notice: Refer to Fastener Notice in Service Precautions.

Install the brake master cylinder mounting nuts.
^ Tighten the nuts to 20 Nm (15 ft. lbs.).
13. Secure the brake master cylinder pipes to the 6-position pipe clip along the frame rail.
14. Install the brake master cylinder auxiliary reservoir.





15. Install the underhood electrical center bracket to the vehicle and install the electrical center (1) into position on the bracket.





16. Connect the electrical connector to the brake fluid level sensor, then press forward on the CPA tab of the connector to secure.
17. Install the cover to the underhood electrical center.
18. Connect the negative battery cable.