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Diagnostic Procedure

WARNING: This page is about a different car, the 2002 Chevrolet Malibu. However, it is still accessible from the selected car via links, so may be relevant.
  1. Perform DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM. Go to next step.
  2. Install scan tool. Turn ignition on, engine off. Using scan tool, command A/C Relay ON and OFF in PCM Special Functions, Engine Output Controls list. If A/C Relay turns ON and OFF with each command, problem is intermittent. Check wiring and connections. If A/C Relay does not turn ON and OFF with each command, go to next step.
  3. Turn ignition off. Disconnect A/C compressor clutch relay. Turn ignition on, engine off. Probe battery positive voltage circuit of A/C compressor clutch relay with a test light connected to ground. If test light illuminates, go to next step. If test light does not illuminate, go to step  10.
  4. Connect a test light between A/C compressor clutch relay control circuit and battery positive voltage circuit. Using scan tool, command A/C Relay ON and OFF. If test light turns ON and OFF with each command, go to step  8. If test light does not turn ON and OFF with each command, go to next step.
  5. If test light remains illuminated with each command, go to step  7. If test light does not remain illuminated with each command, go to next step.
  6. Test A/C compressor clutch relay control circuit for a short to voltage or an open. Repair as necessary, then go to step  13. If circuit is okay, go to step  9.
  7. Test A/C compressor clutch relay control circuit for a short to ground. Repair as necessary, then go to step  13. If circuit is okay, go to step  9.
  8. Inspect for poor connections at A/C compressor clutch relay. Repair as necessary, then go to step  13. If connections are okay, go to step  11.
  9. Inspect for poor connections at PCM harness connector. Repair as necessary, then go to step  13. If connections are okay, go to step  12.
  10. Repair A/C compressor clutch relay battery positive voltage circuit. After repairs are complete, go to step  13.
  11. Replace A/C compressor clutch relay. See COMPRESSOR CLUTCH RELAY  under REMOVAL & INSTALLATION. After replacement, go to step  13.
  12. Replace and reprogram PCM. See POWERTRAIN CONTROL MODULE in REMOVAL, OVERHAUL & INSTALLATION article in ENGINE PERFORMANCE. After replacement, go to next step.
  13. Use scan tool to clear DTCs. Start engine. Increase engine speed to greater than 80 RPM. If DTC P1546 resets, go to step  2. If DTC P1546 does not reset, system is okay.
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