LEMON Manuals: Even more car manuals for everyone
Home >> Saab >> 1999 >> 9-3 Base, 4D Hatchback, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics - TRIONIC T5 Fuel Control System >> Diagnostic Tests >> DTC P0506-0507: Idle Speed Control (ISC) Malfunction

DTC P0506-0507: Idle Speed Control (ISC) Malfunction

  1. With engine idling, pinch off inlet hose at Idle Air Control (IAC) valve located under upper engine cover, on passenger side of throttle body. If engine idle speed drops sharply, go to next step. If idle speed does not drop sharply, check for vacuum leaks after throttle valve, incorrect throttle valve adjustment, leaking brake power booster or stuck-open purge valve. Repair as necessary and go to step  5 .
  2. Turn ignition off. Disconnect IAC valve harness connector. Start engine and allow to idle. Connect SST 86 11 857 test light (or equivalent) between IAC valve harness connector terminal No. 2 (Green/Red wire) and ground. See Figure . If test light illuminates, go to next step. If test light does not illuminate, repair faulty circuit between IAC valve harness connector terminal No. 2 and fuse No. 16B located in dashboard fuse block (Green/Red wire). See Figure . Go to step  5 .
  3. Turn ignition off. Connect test light between IAC valve harness connector terminal No. 1 (Blue/Purple wire) and battery positive terminal. Turn ignition on. If test light illuminates, go to next step. If test light does not illuminate, repair faulty circuit between IAC valve harness connector terminal No. 1 and ECM harness connector terminal No. 49 (Blue/Purple wire). See Figure for ECM terminal identification. Go to step  5 .
  4. Remove fuse No. 28 in dashboard fuse block. Test light should go out or shine very dimly. If operation is as specified, replace IAC valve. If operation is not as specified, repair faulty circuit between IAC valve harness connector terminal No. 1 and ECM harness connector terminal No. 49 (Blue/Purple wire). Go to next step.
  5. Connect TECH 2 scan tool to DLC. Clear DTCs. Test drive vehicle at varying engine loads and RPM for at least one minute, until coolant temperature reaches 140°F (60°C). Vehicle speed should exceed 13 MPH some time during test. Stop vehicle and apply hand brake. Turn off all electrical loads and place vehicle in PARK if equipped with A/T. Allow engine to idle for 10 minutes to stabilize idle speed. Go to next step.
  6. Turn all electrical loads on and place vehicle in DRIVE if equipped with A/T. Allow engine to idle for 10 minutes to stabilize idle speed. Use scan tool to check for DTCs. If DTC P0506-0507 is present, problem still exists. Substitute known good ECM and retest system. See ENGINE CONTROL MODULE (ECM) under COMPUTERIZED ENGINE CONTROLS in REMOVAL, OVERHAUL & INSTALLATION article.
scientia non olet · About LEMON Manuals