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Home >> Cadillac >> 1997 >> Catera >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - Tests W/Codes - 3.0L >> Diagnostic Trouble Codes >> DTC P1112 - Intake Plenum Switchover Valve Control >> Diagnostic Procedures

Diagnostic Procedures

  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the BASIC TESTING article. After performing OBD system check, go to next step.
  2. Turn ignition on, with engine off. Using scan tool, command valve on and off. If valve turns on and off with each command, go to next step. If valve does not turn on and off with each command, go to step 5).
  3. Turn ignition off. Disconnect ECM connector located in engine compartment, in relay center. Jumper main relay control circuit to ground. Using DVOM on 10-amp scale, measure current between ground and valve control circuit at ECM harness connector for 2 minutes. If current draw is 0.1-0.75 amp, see DIAGNOSTIC AIDS. If current draw is not 0.1-0.75 amp, go to next step.
  4. Turn ignition off. Disconnect valve connector. Using DVOM, measure resistance between ground and valve control circuit at ECM harness connector. If resistance is infinite, go to step 11). If resistance is not infinite, go to step 9).
  5. Turn ignition off. Disconnect valve connector. Connect test light between valve harness connector terminals. Turn ignition on. Using scan tool, command valve 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.
  6. With test light connected to ground, probe switched battery feed circuit at valve harness connector. If test light is on, go to next step. If test light is off, go to step 10).
  7. Turn ignition off. Reconnect valve connector. Disconnect ECM connector located in engine compartment, in relay center. Jumper main relay control circuit to ground. Using a fused jumper wire connected to ground, probe valve control circuit at ECM harness connector. If solenoid operates, go to step 12). If solenoid does not operate, go to step 9).
  8. Check connections at valve. Repair as necessary, then go to step 14). If connections are okay, go to step 11).
  9. Repair valve control circuit, then go to step 14).
  10. Repair switched battery feed circuit to valve, then go to step 14).
  11. Replace valve, then go to step 14).
  12. Check for poor connections and terminal tension at ECM harness connector. Repair as necessary, then go to step 14). If connections and terminals are okay, go to next step.
  13. Replace ECM. New ECM must be programmed with theft deterrent module frequency code currently on vehicle. Go to next step.
  14. Using scan tool, clear DTCs. Turn ignition off for 15 seconds. Start engine and operate vehicle. Check for DTCs. If DTC P1112 is set, go to step 2). If DTC P1112 is not set, go to next step.
  15. If other DTCs were present during OBD system check and have not been diagnosed, go to applicable DTC. If no other DTCs are present, system is okay.
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