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Home >> Cadillac >> 1998 >> DeVille Concours >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - Tests W/Codes >> Diagnostic Trouble Codes >> DTC P1323 - Ignition Control (Ic) Module 24X Reference Circuit Low Frequency >> Diagnostic Procedures
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Diagnostic Procedures

  1. Perform POWERTRAIN ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK , then go to next step.
  2. Using scan tool, check if DTC P1376 is also present. If DTC P1376 is present, diagnose this DTC first. If DTC is not present, go to next step.
  3. Store fluid life index as indicated on scan tool. Turn ignition off and wait 30 seconds, then disconnect IC module harness connector C4 and PCM harness connector C2. Using DVOM, check resistance between ground and 24X reference circuit at PCM harness connector C2. If resistance is greater than 10,000 ohms, go to next step. If resistance is not greater than 10,000 ohms, go to step 8).
  4. Check resistance of 24X reference signal circuit between PCM and IC harness connector terminals. If resistance is 5 ohms or less, go to next step. If resistance is not 5 ohms or less, go to step 9).
  5. Reconnect IC module harness connector C4. Turn ignition on. Check voltage between ground and 24X reference signal circuit at PCM harness connector C2. If voltage is greater than 4.2 volts, go to next step. If voltage is not greater than 4.2 volts, go to step 10).
  6. Turn ignition off. Disconnect IC module harness connector C2. Using 6-Pin IC module diagnostic jumpers, jumper the following IC module connector C4 terminals to the following module terminals:
    • C4 Terminal "A" To Module Pin "A"
    • C4 Terminal "B" To Module Pin "B"
    • C4 Terminal "C" To Module Pin "C"
    • C4 Terminal "D" To Module Pin "D"
    • C4 Terminal "E" To Module Pin "E"
    • C4 Terminal "F" To Module Pin "F"

    Set DVOM to 400 mV AC scale and push Hz button. Connect DVOM between terminal "A" jumper and ground. Start engine and check frequency. If frequency is less than 340 Hz, go to step 10). If frequency is not less than 340 Hz, go to next step.

  7. Remove all jumper wire connections. Reconnect IC module connector C4. Clear DTC. Start and idle engine. Using scan tool, select DTC INFO then FAIL THIS IGN modes. If DTC P1323 resets, go to step 12). If DTC does not reset, fault is not present. See DIAGNOSTIC AIDS.
  8. Check for short to ground in 24X reference signal circuit.
  9. Repair open in 24X reference signal circuit.
  10. Check terminal contact at IC module harness connector C4. Repair as necessary. If terminal contact is okay, go to next step.
  11. Replace IC module.
  12. Check 24X reference signal circuit terminal contact at PCM harness connector C2. Repair as necessary. If terminal contact is okay, go to next step.
  13. Replace PCM. Program replacement PCM using required equipment.
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