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Home >> Suzuki >> 2002 >> XL-7 Plus >> Repair and Diagnosis >> External Pages >> Different car >> Section 7 (Engine Controls - Self-Diagnostics - 2.2L) >> Diagnostic Tests >> DTC P0506: Idle Control System - Rpm Lower Than Expected >> Diagnostic Procedure
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Diagnostic Procedure

WARNING: This page is about a different car, the 2002 Isuzu Rodeo Sport and 2002 Isuzu Rodeo. However, it is still accessible from the selected car via links, so may be relevant.
  1. Perform ON-BOARD DIAGNOSTIC II SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM. After performing OBD-II system check, go to next step.
  2. Using scan tool, read DTCs. If any other DTCs are set, perform appropriate test before proceeding. See DIAGNOSTIC TROUBLE CODE DEFINITIONS  . If no other DTCs are set, go to next step.
  3. Start engine. Turn all accessories off. Using scan tool, monitor ENGINE SPEED and command engine speed up to 1500 RPM, down to 500 RPM, and up to 1500 RPM. If ENGINE SPEED remains within 50 RPM of desired RPM for each command, check for intermittent problem. See DIAGNOSTIC AIDS  . If engine speed does not respond as specified, go to next step.
  4. Disconnect IAC 4-pin harness connector. IAC is located in throttle body on intake manifold. Install IAC Noid Light (J37027A or equivalent) into IAC harness connector. With engine running, monitor noid lights while commanding engine speed up to 1500 RPM, down to 500 RPM, and back up to 1500 RPM. Both node lights should cycle between Green and Red, but not Off as RPM changes from 500 to 1500 RPM. If lights flash as specified, go to step  6 . If lights do not flash as specified, go to next step.
  5. Check for open, short to ground or short to voltage in IAC "A" high and IAC "A" low, and IAC "B" high and IAC "B" low circuits. See Fig 1 . If problem is found, repair as necessary. After repair is complete, see VERIFYING VEHICLE REPAIR  under SELF-DIAGNOSTIC SYSTEM. If no problem is found, go to step  8 .
  6. Check for tampering to throttle body. Ensure throttle stop screw has not been tampered with. Check for stuck IAC valve or throttle linkage. Check for restrictions, collapse or blockage in air intake system, air ducts or air filter. Check throttle body bore and IAC for excessive deposits. If a problem is found, repair as necessary. If no problem is found, go to next step.
  7. Check for poor, loose or damaged terminal connections in IAC harness connector. If problem is found, repair as necessary. After repair is complete, see VERIFYING VEHICLE REPAIR  under SELF-DIAGNOSTIC SYSTEM. If no problem is found, go to next step.
  8. Check for open, short to ground, short to voltage or shorts to each other in IAC valve solenoids "A" and "B" circuits. If problem was found, go to next step. If no problem was found with IAC valve solenoids, go to step  10 .
  9. Replace IAC valve. After repair is complete, see VERIFYING VEHICLE REPAIR  under SELF-DIAGNOSTIC SYSTEM.
  10. Replace and reprogram PCM. See POWERTRAIN CONTROL MODULE REPLACEMENT  under POWERTRAIN CONTROL MODULE. After repair is complete, see VERIFYING VEHICLE REPAIR  under SELF-DIAGNOSTIC SYSTEM.
Fig 1: Identifying Idle Air Control Circuit
G98E12710Courtesy of ISUZU MOTOR CO.
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