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Home >> Chevrolet >> 2001 >> Prizm Base, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System & Component Testing >> Circuit Tests >> A/C Idle-Up Circuit (Metro) >> Diagnostic Procedure

Diagnostic Procedure

  1. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK under SELF-DIAGNOSTIC SYSTEM in appropriate SELF-DIAGNOSTICS article. After performing OBD system check, go to next step.
  2. Using scan tool, start and warm engine to normal operating temperature. Turn off all accessories and monitor A/C parameters while turning A/C switch on and blower speed switch to any position except off. If scan tool indicates A/C ON with A/C operating, system is functioning normally. If scan tool does not indicate A/C ON with A/C operating, go to next step.
  3. Using a DVOM connected to ground, backprobe PCM connector A/C idle-up signal circuit. See WIRING DIAGRAMS article. If voltage is zero volts, go to next step. If voltage is not zero volts, go to step  6.
  4. Turn A/C off. Using a DVOM connected to ground, backprobe PCM connector A/C idle-up signal circuit. See WIRING DIAGRAMS article. If battery voltage is present, go to step  7. If battery voltage is not present, go to next step.
  5. Turn ignition off. Disconnect PCM connector C3. Back out A/C idle-up signal wire from PCM electrical connector. Reconnect PCM connector C3. Turn ignition on, engine off. Using a DVOM connected to ground, backprobe through PCM connector to PCM A/C idle-up signal circuit. See WIRING DIAGRAMS article. If battery voltage is present, go to next step. If battery voltage is not present, go to step  12.
  6. Check for an open in A/C idle-up signal circuit between PCM and A/C compressor control module. Repair as necessary. After repairs, go to step  13. If circuit is okay, go to step  11.
  7. Start engine. Turn A/C off. Using a DVOM connected to ground, backprobe PCM connector A/C cut-out signal circuit. See WIRING DIAGRAMS article. If voltage is zero volts, go to next step. If voltage is not zero volts, go to step  12.
  8. Start engine. Turn A/C on (A/C operating). Using a DVOM connected to ground, backprobe PCM connector A/C cut-out signal circuit. See WIRING DIAGRAMS article. If battery voltage is present, see DIAGNOSTIC AIDS . If battery voltage is not present, go to next step.
  9. Check for an open in A/C cut-out signal circuit between PCM and A/C compressor control module. Repair as necessary. After repairs, go to step  13. If circuit is okay, go to next step.
  10. Disconnect A/C compressor control module connector. Turn ignition on, engine off. Using a DVOM, measure voltage at A/C compressor control module A/C cut-out signal circuit. See WIRING DIAGRAMS article. If battery voltage is present, go to step  12. If battery voltage is not present, go to next step.
  11. Replace A/C compressor control module. After repairs, go to step  13.
  12. Replace PCM. After repairs, go to next step.
  13. After repairs, operate vehicle within conditions under which original symptom was observed. If system operates properly, repair is complete. If system does not operate properly, see DIAGNOSTIC AIDS  and retest.
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