Town & Country AWD V6-3.8L VIN L (2003)
Vacuum Brake Booster: Testing and Inspection
BASIC TEST
1. With engine off, depress and release the brake pedal several times to purge all vacuum from the power brake booster.
2. Depress and hold the pedal with light effort (15 to 25 lbs. pressure), then start the engine.
The pedal should fall slightly, then hold. Less effort should be needed to apply the pedal at this time. If the pedal fell as indicated, perform the
VACUUM LEAK TEST listed after the BASIC TEST. If the pedal did not fall, continue on with this BASIC TEST.
3. Disconnect the vacuum hose on the vacuum check valve, then place a vacuum gauge in line between the vacuum hose and the valve.
4. Start the engine.
5. When the engine is at warm operating temperature, allow it to idle and check the vacuum at the gauge.
If the vacuum supply is 12 in.Hg (40.5 kPa) or more, the power brake booster is defective and must be replaced. If the vacuum supply is below
12 in.Hg, continue on with this BASIC TEST.
6. Shut off the engine.
7. Connect the vacuum gauge to the vacuum reference port on the engine intake manifold.
8. Start the engine and observe the vacuum gauge.
If the vacuum is still low, check the engine tune and repair as necessary. If the vacuum is above 12 in.Hg, the hose or check valve to the booster
has a restriction or leak.
Once an adequate vacuum supply is obtained, repeat the BASIC TEST.
VACUUM LEAK TEST
1. Disconnect the vacuum hose on the vacuum check valve, then place a vacuum gauge in line between the vacuum hose and the valve.
2. Start the engine.
3. Allow the engine to warm up to normal operating temperature and engine idle.
4. Using vacuum line pliers, close off the vacuum supply hose near the booster, but before the vacuum gauge, then observe the vacuum gauge.
If the vacuum drop exceeds 1.0 in.Hg (3.3 kPa) in one minute, repeat the above steps to confirm the reading. The vacuum loss should be less than
1.0 in.Hg in one minute time span. If the loss is more than 1.0 in.Hg, replace the power brake booster. If it is not, continue on with this test.
5. Remove the pliers from the hose temporarily.
6. Apply light effort (approximately 15 lbs. of force) to the brake pedal and hold the pedal steady. Do not move the pedal once the pressure is
applied or the test results may vary.
7. Have an assistant reattach the vacuum line pliers to the vacuum supply hose.
8. Allow 5 seconds for stabilization, then observe the vacuum gauge.
If the vacuum drop exceeds 3.0 in.Hg (10 kPa) in 15 seconds, repeat the above steps to confirm the reading. The vacuum loss should be less than
3.0 in.Hg in 15 seconds time span. If the loss is more than 3.0 in.Hg, replace the power brake booster. If it is not, the booster is not defective.
9. Remove the pliers and vacuum gauge.
