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Home >> Saab >> 1988 >> 900 Base, 2D Convertible, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Fuel Injection System - LH-JETRONIC >> Testing - SAAB >> Component Testing >> Automatic Idle Control (AIC)

Automatic Idle Control (AIC)

  1. Ensure ECU and all control systems are properly connected. Start engine and run at normal operating temperature. Ground GRN/RED wire at test connector (connector is located near evaporator housing). See Figure .
  2. Remove ground wire. When wire is removed, engine RPM should increase, then return to idle. If engine RPM does not respond, go to step 3). If engine RPM responds correctly, reconnect ground wire, set basic idle speed, and disconnect ground wire. Refer to appropriate article in TUNE-UP section for idle speed adjustment procedure.
  3. Pull back rubber boot from AIC actuator plug (at actuator). Connect positive voltmeter lead to terminal No. 2 (BLU/RED) of AIC connector. See Fig 1 .
    Fig 1: AIC Switch Terminal Locations
    G35436Courtesy of SAAB-SCANIA OF AMERICA, INC.
  4. Connect negative lead of voltmeter to ground. Start engine and check voltage reading. Voltmeter should indicate battery voltage.
  5. Connect positive voltmeter lead to terminal No. 2 of AIC connector. Connect negative lead to terminal No. 3 (YEL/RED) of AIC connector. Verify that voltage reading and idle speed change as A/C system is turned on and off. It is not important what voltage is, only that voltage changes.
  6. Turn off engine. If voltage and idle speed changed as described, system is okay. If voltage changes but idle speed does not, go to next step. If voltage does not change, go to step 8).
  7. Check all AIC system hoses for damage. Disconnect AIC actuator plug from actuator. Check resistance through actuator windings by measuring resistance between actuator terminals No. 1 and No. 3. Resistance should be 36-44 ohms. Replace actuator if defective, and retest system. Reconnect harness plug to AIC actuator.
    NOTE: Ignition must be off when connecting or disconnecting the ECU. Remove wiring harness connector from ECU, prior to testing. Repair any problems as they are found, before proceeding to next step in test procedure. Always probe from rear of connector to avoid enlarging connector pin holes.
  8. Disconnect ECU harness connector. Check continuity between ECU harness connector terminals No. 10 and No. 23. See Figure . Resistance should be 36-44 ohms. If resistance is incorrect, go to step 10).
  9. If resistance is correct and problem still exists, substitute a new ECU, connect ECU harness connector, and recheck system operation. Proceed to FUEL INJECTION BASE LINE VALUE in ADJUSTMENTS  .
  10. Check for battery voltage at ECU harness connector pin No. 16 when A/C compressor is engaged. If resistance is correct and problem still exists, substitute a new ECU, connect ECU harness connector, and recheck system operation.
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