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Home >> Chevrolet >> 2001 >> Impala Base, 3.8 K >> Repair and Diagnosis >> External Pages >> Different car >> Section 36 (HVAC Systems - Automatic) >> Diagnostic Tests >> DTC P1546: A/C Relay Circuit Malfunction >> Diagnostic Procedure

Diagnostic Procedure

WARNING: This page is about a different car, the 2002 Oldsmobile Intrigue. However, it is still accessible from the selected car via links, so may be relevant.
  1. If diagnostic system check was not performed, go to DIAGNOSTIC SYSTEM CHECK . If diagnostic system check was performed, go to next step.
  2. Install a scan tool. Turn ignition on. With a scan tool, command the A/C Relay ON and OFF in the Special Functions, Engine Output Controls list. Does the A/C compressor clutch relay turn ON and OFF with each command? If so, condition is intermittent. See INTERMITTENTS  under TROUBLE SHOOTING. If not, go to next step.
  3. Turn ignition off. Disconnect the A/C compressor clutch relay. Turn ignition on. Probe the battery positive voltage circuit of the A/C compressor clutch relay with a test light that is connected to ground. Does the test light illuminate? If so, go to next step. If not, go to step  10.
  4. Connect a test light between the control circuit of the A/C compressor clutch relay and the battery positive voltage circuit of the A/C compressor clutch relay. With a scan tool, command the A/C Relay ON and OFF. Does the test light turn ON and OFF with each command? If so, go to step  8. If not, go to next step.
  5. Does the test light remain illuminated with each command? If so, go to step  7. If not, go to next step.
  6. Check the A/C compressor clutch relay control circuit for a short to voltage or an open. Did you find and correct the condition? If so, go to step  13. If not, go to step  9.
  7. Check the A/C compressor clutch relay control circuit for a short to ground. Did you find and correct the condition? If so, go to step  13. If not, go to step  9.
  8. Inspect for poor connections at the A/C compressor clutch relay. Did you find and correct the condition? If so, go to step  13. If not, go to step  1.
  9. Inspect for poor connections at the harness connector of the PCM. Did you find and correct the condition? If so, go to step  13. If not, go to step  12.
  10. Repair the battery positive voltage circuit of the A/C compressor clutch relay. After repairs are complete, go to step  13.
  11. Replace the A/C compressor clutch relay. See COMPRESSOR RELAY under REMOVAL & INSTALLATION in INTRIGUE article in MANUAL A/C-HEATER SYSTEMS. After repairs are complete, go to step  13.
  12. Replace the PCM. See POWERTRAIN CONTROL MODULE under COMPUTERIZED ENGINE CONTROLS in REMOVAL, OVERHAUL & INSTALLATION - AURORA & INTRIGUE article in ENGINE PERFORMANCE. After repairs are complete, go to next step.
  13. Use the scan tool in order to clear the DTCs. Operate the vehicle within the Conditions for Running the DTC as specified above. Does the DTC reset? If so, go to step  2. If not, system is okay.
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