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Boost Control System Check (VIN 1)

  1. Perform On-Board Diagnostic (OBD) System Check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK in the BASIC TESTING - 3.8L article. After performing OBD system check, go to next step.
  2. Disconnect boost control solenoid harness connector located at left rear of engine, near valve cover. Turn ignition on. Connect a test light between ignition feed circuit at boost control solenoid harness connector and ground. If test light illuminates, go to next step. If test light does not illuminate, go to step 11).
  3. Connect test light between boost control solenoid harness connector terminals. If test light illuminates, go to step 12). If test light does not illuminate, go to next step.
  4. Install scan tool. Select boost control solenoid OUTPUT CONTROL with scan tool. Observe test light while turning boost control solenoid output on with scan tool. If test light illuminates when solenoid output is commanded on, go to next step. If test light does not illuminate when solenoid output is commanded on, go to step 14).
  5. Reconnect boost control solenoid harness connector. Disconnect boost signal vacuum hose between solenoid and by-pass valve actuator located above boost control solenoid. Connect vacuum gauge to boost control solenoid. With transaxle in Park, start and idle engine. Observe vacuum gauge reading. If vacuum is not present, go to next step. If vacuum is present, go to step 15).
  6. Using scan tool, turn off boost control solenoid. Observe vacuum gauge. Vacuum reading should be more than 15 in. Hg. If vacuum reading is as specified, go to next step. If vacuum reading is not as specified, check for restriction in vacuum source to boost control solenoid. If restriction is not found, replace boost control solenoid, then go to step 17).
  7. Check for restriction in boost signal hose between boost control solenoid and by-pass valve actuator. If restriction is not found, go to next step. If restriction is found, go to step 17).
  8. Reconnect boost signal vacuum hose between boost control solenoid and by-pass valve actuator. Connect vacuum gauge to read inlet vacuum signal to by-pass valve actuator. Start engine and idle in Park. Observe vacuum gauge reading. Vacuum reading should be more than 15 in. Hg. If vacuum reading is as specified, see DIAGNOSTIC AIDS. If vacuum reading is not as specified, go to next step.
  9. Repair restriction in inlet vacuum signal hose to by-pass valve actuator or blocked inlet vacuum source, then go to step 17).
  10. Check for restriction in vacuum hose to boost control solenoid. Repair as necessary, then go to step 17). If restriction is not found, replace boost control solenoid, then go to step 17).
  11. Check boost control solenoid ignition feed circuit fuse. If fuse is okay, locate and repair open in ignition feed circuit to boost control solenoid, then go to step 17). If fuse is blown, locate and repair short to ground in ignition feed circuit, then go to step 17).
  12. Turn ignition off. Disconnect PCM harness connector. Turn ignition on. Connect test light between boost control solenoid harness connector terminals. If test light illuminates, go to next step. If test light does not illuminate, go to step 16).
  13. Locate and repair short to ground in boost control solenoid control circuit, then go to step 17).
  14. Turn ignition off. Disconnect PCM harness connector. Turn ignition on. Check boost control solenoid control circuit for an open or short to voltage. Repair as necessary, then go to step 17). If circuit is okay, go to step 16).
  15. Check for poor terminal connections at boost control solenoid. Repair as necessary. If connections are okay, replace boost control solenoid, then go to step 17).
  16. Check boost control solenoid control circuit for a poor terminal connection at PCM. Repair as necessary. If connection is okay, replace PCM, then go to next step.
  17. Disconnect inlet vacuum signal hose from by-pass valve actuator. Start engine and let idle. Select OUTPUT TESTS, BOOST SOL. on scan tool. Observe MAP reading on scan tool while cycling boost control solenoid on and off. If MAP sensor value decreases while boost control solenoid is commanded on, and increases while boost solenoid is commanded off, system is working correctly. If MAP sensor value is not as specified, go to step 2).
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