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Home >> Cadillac >> 1996 >> Seville SLS >> Repair and Diagnosis (Single Page) >> Engine Performance >> System >> Engine Control System - Tests W/Codes >> Diagnostic Trouble Codes >> DTC P1320 - Ignition Control (Ic) Module 4X Reference Circuit Intermittent No Pulse >> Diagnostic Procedures
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Diagnostic Procedures

  1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
  2. Using scan tool, check if DTC(s) P0322, P1323 or P1375 is also present. If any of the DTC(s) are present, diagnose affected DTC(s) first. If DTC(s) are not present, go to next step.
  3. Disconnect IC module harness connector C3. Turn ignition on. Using DVOM, check voltage between ground and ignition feed circuit at IC module harness connector C3 terminal. If voltage is 10 volts or greater, go to next step. If voltage is less than 10 volts, go to step 10).
  4. Turn ignition off. Reconnect IC module harness connector C3. Disconnect IC module harness connector C4. Store fluid life index as indicated on scan tool. Disconnect PCM harness connector C2. Using DVOM, check resistance between ground and fuel control circuit at PCM harness connector terminal. If resistance is greater than 10,000 ohms go to next step. If resistance is not greater than 10,000 ohms, go to step 11).
  5. Check resistance of fuel control circuit between IC module harness connector and PCM harness connector terminal. If resistance is 5 ohms or less, go to next step. If not 5 ohms or less, step 12).
  6. Turn ignition on. Check voltage between ground and fuel control circuit at IC harness connector C2 terminal. If voltage is less than .5 volt go to next step. If not, go to step 13).
  7. Reconnect IC module harness connector C4. Check voltage between ground and fuel control circuit at PCM harness connector C2. If voltage is greater than 4.2 volts, go to next step. If voltage is 4.2 volts or less, go to step 14).
  8. 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 "C" jumper and ground. Start engine and check frequency. If frequency is less than 30 Hz, go to step 10). If frequency is not less than 30 Hz, go to next step.

  9. 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 P1320 resets, go to step 16). If DTC does not reset, fault is not present. See DIAGNOSTIC AIDS.
  10. Check for no voltage to IC module caused by a faulty fuse due to short in ignition feed circuit, open in ignition feed circuit or shorted IC module. Repair as necessary.
  11. Repair short to ground in fuel control circuit to IC module.
  12. Repair open in fuel control circuit to IC module.
  13. Repair short to voltage in fuel control circuit to IC module.
  14. Check terminal contact at IC module harness connector C4. Repair as necessary. If terminal contact is okay, go to next step.
  15. Replace IC module.
  16. Check fuel control circuit terminal contact at PCM harness connector C2. Repair as necessary. If terminal contact is okay, go to next step.
  17. Replace PCM. Program replacement PCM using required equipment.
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