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Home >> Saturn >> 2001 >> SC1 Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - Basic Diagnostic Procedures >> Engine Controls Circuit Checks >> Power Relay Circuit (CATERA)
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Power Relay Circuit (CATERA)

  1. If powertrain diagnostic system check has already been performed, go to next step. If powertrain diagnostic system check has not been performed, go to POWERTRAIN DIAGNOSTIC SYSTEM CHECK in appropriate SELF-DIAGNOSTICS article.
  2. Turn ignition off. Disconnect engine controls power relay located in ECM housing. Using test light connected to ground, probe battery feed circuits at relay cavities. If test light illuminates for both circuits, go to next step. If test light does not illuminate for both circuits, go to step  12.
  3. Turn ignition off. Disconnect ECM harness connector C2. Using test light connected to ground, probe engine controls power relay control circuit at relay cavity. Turn ignition on. If test light illuminates, go to step  10. If test light does not illuminate, go to next step.
  4. Turn ignition off. Using test light connected to battery voltage, probe engine controls power relay control circuit at relay cavity. If test light illuminates, go to step  11. If test light does not illuminate, go to next step.
  5. Reconnect engine controls power relay. Using test light connected to ground, probe engine controls power relay circuit at ECM harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step  8.
  6. Using DVOM set to 10-amp scale, measure current between chassis ground and engine controls power relay control circuit at ECM harness connector C2 for 2 minutes. If current draw is 100-200 mA, go to next step. If current draw is not 100-200 mA, go to step  14.
  7. Remove DVOM. Using fused jumper wire, jumper engine controls power relay circuit to ground. Using test light connected to ground, probe each ECM switched battery feed circuits (3) at ECM harness connector C2. If test light illuminates for all 3 circuits, go to step  15. If test light does not illuminate for all 3 circuits, go to step  9.
  8. Check for open or high resistance in engine controls power relay control circuit. Repair as necessary. After repairs, go to step  18. If circuit is okay, go to step  13.
  9. Check for open or high resistance in engine switched battery feed circuits between engine controls power relay and ECM. Repair as necessary. After repairs, go to step  18. If circuits are okay, go to step  13.
  10. Repair short to voltage in engine controls power relay control circuit. After repairs, go to step  18.
  11. Repair short to ground in engine controls power relay control circuit. After repairs, go to step  18.
  12. Repair battery feed circuit. After repairs, go to step  18.
  13. Check for faulty connections at engine control power relay. Repair as necessary. After repairs, go to step  18. If connections are okay, go to next step.
  14. Replace engine controls power relay. After repairs, go to step  18.
  15. Check ignition feed and battery feed circuits to ECM for voltage. Check ECM ground circuit for loose connections, corrosion, open or high resistance. Repair as necessary. After repairs, go to step  18. If circuits are okay, go to next step.
  16. Check for faulty ECM harness connections. Repair as necessary. After repairs, go to step  18. If connections are okay, go to next step.
  17. Replace ECM. Perform ECM relearn procedures. After repairs, go to next step.
  18. Using scan tool, attempt communication with ECM. If communication is possible, system is okay. If communication is not possible, perform powertrain diagnostic system check. See POWERTRAIN DIAGNOSTIC SYSTEM CHECK in appropriate SELF-DIAGNOSTICS article.
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