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Home >> Cadillac >> 1996 >> Seville STS >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - Tests W/Codes >> Diagnostic Trouble Codes >> DTC P1376 - Ignition Ground Circuit >> Diagnostic Procedures

Diagnostic Procedures

  1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
  2. Turn ignition on. Using scan tool, select FAILURE REC. in DTC mode. Note REF VOLTS LOW display when this DTC set. If voltage reading is 1.4 volts or greater, go to next step. If voltage reading is less than 1.4 volts, go to step 8).
  3. Store fluid life index as indicated on scan tool. Turn ignition off and wait 30 seconds, then disconnect PCM harness connector C2. Disconnect IC module harness connector C4. Turn ignition on. Using scan tool, check voltage between ground and reference low circuit at PCM harness connector C4 terminal. If voltage is greater than .1 volt, go to step 9). If voltage is less than .1 volt, go to next step.
  4. Check resistance of reference low circuit between IC module harness connector and PCM harness connector terminals. If resistance is 5 ohms or greater, go to step 10). If resistance is less than 5 ohms, go to next step.
  5. Turn ignition key on. Check voltage to ground at reference low circuit at IC module harness connector C4 terminal. If voltage reading is .1 volt or greater, go to next step. If voltage reading is less than .1 volt, fault is not present. See DIAGNOSTIC AIDS.
  6. Turn ignition off. Disconnect IC module harness connector C3. Check resistance to ground at IC module harness connector C3 terminal "A" (ground circuit). If resistance is 5 ohms or greater, go to step 11). If resistance is less than 5 ohms, go to next step.
  7. Check terminal contact at IC module and PCM harness connectors. Check PCM and IC module ground connections. Repair as necessary. Reconnect all harness connectors. Clear this DTC. Start engine. If DTC resets, go to step 13). If DTC does not reset, fault is not present.
  8. Turn ignition off. Disconnect both PCM harness connectors. Using DVOM, check resistance between ground and PCM ground circuits in PCM terminal. If resistance is greater than 5 ohms in any of the terminals, go to step 12). If not, check PCM grounds.
  9. Repair short to voltage in reference low circuit.
  10. Repair open in reference low circuit.
  11. Repair open in ground circuit to IC module.
  12. Repair open in circuits that had high resistance.
  13. Replace IC module.
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