Diagnostic Aids

Enter this test only when all steps under QUICK TEST have been successfully completed and engine still does not start or if directed here from another test or chart. This test is only intended to diagnose compuvalve MAP/BARO circuits.

1. 1) Check MAP PID
   
   Connect New Generation Star (NGS) scan tool to Data Link Connector (DLC). Turn ignition switch to ON position (engine off). Using scan tool, access MAP PID. If MAP PID value is about local barometric pressure, go to next step. If MAP PID value is not about local barometric pressure, replace compuvalve.
2. 2) Check MAP/BARO Sensor
   
   Leave scan tool connected. Start engine. Using scan tool, access MAP PID. If MAP PID value is 8-12 psi, go to next step. If MAP PID value is not 8-12 psi, go to step  4).
3. 3) Check MAP PID While Changing Throttle Angle
   
   Leave scan tool connected. With engine running, use scan tool and access MAP PID. Monitor MAP PID while changing throttle angle rapidly. If MAP PID changes from about 4 psi at closed throttle to about 14 psi at WOT, system is operating correctly at this time. See INTERMITTENT TESTS . If MAP PID does not change as specified, go to next step.
4. 4) Check Vacuum Source To Compuvalve
   
   Connect vacuum gauge to MAP vacuum supply line. Start engine. If vacuum gauge reads manifold vacuum, replace compuvalve. If vacuum gauge does not read manifold vacuum, repair vacuum supply line. Clear DTCs and retest.