Diagnostic Aids
Check for the following conditions:
- PCM will not enable catalyst test until the following conditions are met:
- Engine idle speed is within 100 RPM of desired idle.
- Throttle Position (TP) is one percent or less.
- Short term integrator is -20-20 percent.
- Catalyst test will abort if vehicle conditions fall outside conditions listed below while test is running:
- Engine idle speed is within 125 RPM of desired idle.
- Throttle Position (TP) is one percent or less.
- Short term integrator is -20-20 percent.
- Catalyst test may abort due to a change in engine load (i.e., A/C, cooling fan). If this problem occurs, use scan tool to force cooling fans on, then return to step 2 in procedure.
- Number of attempted tests is limited to 18 per key cycle.
- More than 6 tests may have to be attempted to get 6 completed tests. An aborted test counts as an attempted test.
- If 18 tests have been attempted, and a decision has not been made this key cycle, turn key off for 30 seconds. Start vehicle and operate engine within code enable criteria, including 10 minute engine run time.
- After returning to idle, HO2S 1 signal may stay rich or lean for several seconds, causing test to be delayed.
- Inspect PCM harness connectors for backed-out terminals, improper mating, broken locks, improperly-formed or damaged terminals, and faulty terminal-to-wire connections. Use a corresponding mating terminal in order to test for proper terminal tension.
- Inspect wiring harness for damage. If harness appears to be okay, observe display on scan tool while moving connectors and wiring harnesses related to sensor. A change in display will indicate location of fault.
NOTE:
When using scan tool to force cooling fans on, use NEXT LIST and PREVIOUS LIST soft keys to enter catalyst data list. If catalyst data list is not entered this way, cooling fan control will be canceled.