Test Description

The following list gives a description for appropriate step numbers in diagnostic procedure.

1. 1
   
   The DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS, prompts technician to complete some basic checks and store "Freeze Frame" data on scan tool if applicable. This creates an electronic copy of data taken when fault occurred. Information is then stored in scan tool for later reference.
2. 2
   
   This step checks whether PCM is responding to electrical load idle-up inputs by commanding Idle Air Control (IAC) valve to increase IAC Motor Command percentage. IAC Motor Command parameter on scan tool should increase 2-3 percent when operating the accessory. If scan tool does not indicate an increase in IAC Motor Command when accessory is turned ON, PCM may not be receiving idle-up signal.
3. 3
   
   This step checks whether PCM is responding to idle-up input signals from A/C compressor control module. PCM commands IAC valve to increase IAC Motor Command percentage when receiving idle-up signal. IAC Motor Command parameter on scan tool should increase 4-11 percent when operating A/C. If scan tool does not indicate an increase in IAC Motor Command when A/C is turned ON, PCM may not be receiving idle-up signal.
4. 4
   
   This step checks whether PCM is responding to electrical load idle-up input of Power Steering Pressure (PSP) switch. PCM commands IAC valve to increase IAC Motor Command percentage when receiving PSP idle-up signal. IAC Motor Command parameter on scan tool should increase 2-3 percent when increasing power steering system pressure. If scan tool does not indicate an increase in IAC Motor Command when accessory is turned ON, PCM may not be receiving idle-up signal.
5. 6
   
   This step checks for voltage from PCM or for an open or a short to ground in PSP switch signal circuit.
6. 7
   
   This step checks for an inadequate ground connection at power steering pump or a faulty PSP switch.
7. 10
   
   This step checks whether PCM is receiving A/C ON signal from A/C compressor control module. If scan tool indicates ON, but A/C compressor is not operating, there may be a short to ground in A/C Cut-Out Control circuit. Following "No" diagnostic path will locate problem.
8. 11
   
   A/C idle-up signal circuit at PCM should indicate zero volts with A/C ON (operating).
9. 12
   
   A/C idle-up signal circuit at PCM should indicate battery voltage with A/C OFF (not operating).
10. 15
    
    A/C cut-out signal circuit at PCM should indicate zero volts with A/C OFF (not operating).
11. 16
    
    A/C cut-out signal circuit at PCM should indicate battery voltage with A/C ON (operating).