BES Subject: Temporary reduction in power brake assist in extreme cold weather

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Angelica Preston
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BES 10-06 Subject: Temporary reduction in power brake assist in extreme cold weather Vehicles Involved: Models: 2009 BUICK ENCLAVE From 9J100008 to 9J190898 2009 CHEVROLET TRAVERSE From 9S100002 to

1 BES Subject: Temporary reduction in power brake assist in extreme cold weather Vehicles Involved: Models: 2009 BUICK ENCLAVE From 9J to 9J CHEVROLET TRAVERSE From 9S to 9S GMC ACADIA From 9J to 9J SATURN OUTLOOK From 9J to 9J Condition: If the brake check valves are NOT installed correctly, an increased amount of brake pedal effort will be required to obtain brake function, and the brake assist system will NOT perform as designed. Repair: Replace the first design brake booster vacuum hose check valve (1) with a second design brake booster vacuum hose check valve (2). An arrow on the second design check valve indicates the vacuum draw direction (3). 1. Remove the fuel injector sight shield (engine cover) from the engine.

2 Determine where the two brake booster vacuum hose check valves are located. Refer to callouts 1 and 2 in the illustration 2. Release the quick connect (4) from the power brake booster auxiliary pump (3).

3 3. Remove the protective wrap (5) from the brake booster vacuum hose to locate check valve # (1). 4. Remove the check valve (1) from the brake booster vacuum hose that routes to the power brake booster auxiliary pump (3). 5. Remove the check valve (2) from the brake booster hose that routes to the intake manifold vacuum port (6). Note If necessary, a small amount of denatured alcohol can be used as an assembly aid for installing the vacuum hose to the manifold vacuum port. Do not use soap. 6. Install a new check valve (1) to the brake booster hose that routes to the power brake booster auxiliary pump (3). Ensure the arrow on the check valve (1) points toward the power brake booster auxiliary pump (3) and away from the brake hose tee. Refer to illustration. Ensure the hose is pushed over the check valve barbs and onto the serrated portion of the check valve

4 Brake Check Valve #2 7. Install a new check valve (2) to the brake booster hose that routes to the intake manifold vacuum port. Ensure that the arrow on the check valve (2) points toward the intake manifold vacuum port and away from the brake hose tee. Refer to illustration. Ensure the hose is pushed over the check valve barbs and onto the serrated portion of the check valve. 8. Connect the second piece of brake booster hose that routes to the intake manifold vacuum port (6) to the check valve (2). 9. Connect the second piece of brake booster hose that routes to the power brake booster auxiliary pump to the check valve (1). 10. Install protective wrap (5) over the brake booster hose that routes to the power brake booster auxiliary pump (3). Ensure the protective wrap covers the area of the hose that is directly over the aluminum manifold. Notice If you are unable to pull the protective wrap (5) over the brake check valve (1), remove the protective wrap (5) from the brake hose. Cut the protective wrap (5) into two pieces. Ensure one of the two pieces of protective wrap (5) is cut to 150 mm (6 in) in length. Position the 150 mm (6 in) piece of protective wrap between the brake vacuum hose tee and the brake check valve directly over the aluminum manifold. Position the second piece of the protective wrap (5) between the brake check valve and the power brake booster auxiliary pump (3). 11. Connect the quick connect (4) to the power brake booster auxiliary pump (3). 12. Install the fuel injector sight shield (engine cover). Refer to Fuel Injector Sight Shield Replacement in SI. 13. Start the engine and let it idle for 1 minute. 14. Apply brake pedal 3-5 times to ensure vacuum is getting to the brake booster. If a hard brake pedal is experienced, refer to steps 6-7 to check the brake check valve orientation.

This PI has been revised to add the Saturn VUE and update the Parts Information table and Warranty Information. Please discard PI0746D.

This PI has been revised to add the Saturn VUE and update the Parts Information table and Warranty Information. Please discard PI0746D. Malfunction Indicator Lamp (MIL) On, Poor Acceleration, Throttle Body Freezing, Multiple DTCs Set, Ice Deposits and/or Oil Deposits Present in Air inlet Duct 2008-2011 Buick Enclave 2007-2011 Chevrolet