The IAC solenoid controls engine idle speed and dashpot functions by regulating the volume of air by-passing the throttle plate. IAC solenoid positioning is determined by signals sent from the PCM.
Perform this test when instructed by QUICK TEST or if directed by other test procedures. This test is intended to diagnose:
RPM during SELF-TEST mode.
Wiring harness circuits (IAC and VPWR).
Powertrain Control Module (PCM).
To prevent replacement of good components, be aware the following non-EEC related areas may be at fault:
Engine temperature outside correct operating range.
A/C input (electrical problem).
Incorrect throttle stop adjustment.
Faulty throttle or cruise control linkage.
Code 538 Displayed: System Failed To Recognize WOT Test
Repeat KOER SELF-TEST as follows:
Observe ID Code start of test.
Observe Dynamic Response Code 1 (Code 0 with STAR tester).
Perform brief WOT.
Testing is complete; Diagnostic Test Code (DTC) output begins.
Ensure vehicle speed reached 2000 RPM during WOT. If engine speed did not reach 2000 RPM, check for binding throttle linkage. If Code 538 is present, replace PCM. Repeat QUICK TEST. If Code 538 is not present, vehicle has passed dynamic response test. Service other codes if necessary.
Monday, May 4th, 2009 AT 5:40 AM