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Home >> Nissan-Datsun >> 1998 >> Sentra Base >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls Self-Diagnostics - Introduction >> Self-Diagnostic System >> Fail-Safe Mode
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Fail-Safe Mode

If any malfunctions are detected in Mass Airflow (MAF) sensor, Engine Coolant Temperature (ECT) sensor, Throttle Position (TP) sensor, Traction Control System (TCS) or Powertrain Control Module (PCM) due to an open or short circuit, PCM will enter a fail-safe mode. Driveability will be poor and the MIL will be illuminated. Preprogrammed values will be used for engine operating conditions when PCM goes into fail-safe mode. See FAIL-SAFE MODE OPERATING CONDITIONS  table. Refer to all diagnostic tests that apply for description and testing of circuit affected.

When a failure is detected in the Central Processing Unit (CPU) of PCM, MIL will be illuminated. When PCM is in fail-safe mode, fuel injection, ignition timing, fuel pump operation, IACV-AAC valve and cooling fan operation will be limited. DTC and other PCM information may not be accessible. If PCM fail-safe mode condition is confirmed, replace PCM.

FAIL-SAFE MODE OPERATING CONDITIONS

DTC (1) Circuit Engine Operating Condition
P0100 MAF Sensor 2400 RPM Or Less Due To Fuel Cut
P0110 IAT Sensor PCM Assumes IAT Sensor At 86°F (30°C)
P0115 ECT Sensor ECT Signal Fixed 104-107°F (40-80°C) Based On Engine Run Time
P0120 TP Sensor Poor Acceleration Based On MAF and RPM
P1335 CKP Sensor Ignition Timing Is Fixed. TDC Signal Is Controlled By CMP Sensor & CKP (Phase) Sensor
N/A PCM All Engine Controls Limited Not More Than 3000 RPM. Ignition Timing Is Fixed. (2).Engine Running, Cooling Fan On. (2) Engine Running, Fuel Pump On
(1) Information may not be accessible from PCM.
(2) If engine stalls, operation turns off.