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Home >> Chevrolet >> 1998 >> Metro Base >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System/Component Tests - 1.0L >> Circuit Tests >> A/C Idle-Up Circuit >> Diagnosis & Repair

Diagnosis & Repair

  1. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK under SELF-DIAGNOSTIC SYSTEM in TESTS W/CODES - 1.0L article. After performing OBD system check, go to next step.
  2. Install scan tool. Start and warm engine to normal operating temperature. Turn off all accessories. Using scan tool, monitor A/C parameter while turning A/C switch on and blower speed switch to any position except off. If scan tool indicates on with A/C operating, system is functioning normally. If scan tool does not indicate on with A/C operating, go to next step.
  3. Start engine. Turn A/C on (A/C operating). Using a voltmeter connected to ground, backprobe PCM connector A/C idle-up signal circuit. See WIRING DIAGRAMS - 1.0L article. If voltage is zero volts, go to next step. If voltage is not zero volts, go to step 6).
  4. Start engine. Turn A/C off. Using a voltmeter connected to ground, backprobe PCM connector A/C idle-up signal circuit. See WIRING DIAGRAMS - 1.0L 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 electrical connector C3. Back out A/C idle-up signal wire from PCM electrical connector. Reconnect PCM electrical connector C3. Turn ignition on with engine off. Using a voltmeter connected to ground, backprobe through PCM connector to PCM A/C idle-up signal circuit. See WIRING DIAGRAMS - 1.0L 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 amplifier. 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 voltmeter connected to ground, backprobe PCM connector A/C cut-out signal circuit. See WIRING DIAGRAMS - 1.0L 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 voltmeter connected to ground, backprobe PCM connector A/C cut-out signal circuit. See WIRING DIAGRAMS - 1.0L article. If battery voltage is present, go to 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 amplifier. Repair as necessary. After repairs, go to step 13). If circuit is okay, go to next step.
  10. Disconnect A/C amplifier electrical connector. Turn ignition on with engine off. Using a voltmeter, measure voltage at A/C amplifier A/C cut-out signal circuit. See WIRING DIAGRAMS - 1.0L article. If battery voltage is present, go to step 12). If battery voltage is not present, go to next step.
  11. Replace A/C amplifier. After repairs, go to step 13).
  12. Replace PCM. After repairs, go to next step.
  13. After repairs are completed, operate vehicle within conditions under which original symptom was observed. If system operates properly, repair is complete. If system does not operate properly, go to DIAGNOSTIC AIDS.
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