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Home >> Suzuki >> 1987 >> Samurai Base >> Repair and Diagnosis >> External Pages >> Different car >> Section 17 (Heater And Ventilation) >> Diagnostic Information and Procedures >> DTC P0645, P0646, or P0647 >> Circuit/System Testing
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Circuit/System Testing

WARNING: This page is about a different car, the 2007 Suzuki XL7. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, disconnect the A/C Relay.
  2. Ignition ON, verify that a test lamp does not illuminate between the controlled output circuit, and ground.
    • If the test lamp illuminates, test the relay controlled output circuit for a short to voltage.
  3. Verify that a test lamp illuminates between the relay ignition circuit, and ground.
    • If the test lamp does not illuminate, test the ignition circuit for a short to ground or a open/high resistance. If the circuit tests normal and ignition circuit fuse is open, test or replace the A/C Compressor Clutch Relay.
  4. Verify that a test lamp illuminates between the relay switch B+ circuit, and ground.
    • If the test lamp does not illuminate, test the relay switch B + circuit for a short to ground or a open/high resistance. If the circuit tests normal and the relay coil B+ circuit fuse is open, test the relay ignition output circuit for a short to ground.
    • If the test lamp does not illuminate, test the relay switch ignition circuit for an open/high resistance.
  5. Disconnect the harness connector at the A/C Compressor Clutch Coil.
  6. Test for less than 1 Ω of resistance between the A/C Compressor Clutch Coil terminal B ground circuit terminal and ground.
    • If greater than 1 Ω, test the ground circuit for an open/high resistance.
  7. Connect the harness connector at the A/C Compressor Clutch Coil.
  8. Connect a 3-amp fused jumper wire between the relay switch B+ circuit and the relay controlled output circuit. Verify the A/C Clutch Relay is activated.
    • If the A/C Compressor Clutch Relay does not activate, test the relay controlled circuit for an open/high resistance. If the circuit tests normal, test or replace the A/C Compressor Clutch Relay.
  9. Connect a test lamp between the relay coil ignition circuit, and the relay coil control circuit.
  10. Command the A/C Relay output function ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
    • If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the ECM.
    • If the test lamp is always OFF, test the control circuit for a short to voltage, or an open/high resistance. If the circuit tests normal, replace the ECM.
  11. If all circuits test normal, test or replace the A/C Compressor Clutch Relay.
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