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Home >> Volvo >> 1995 >> 850 Base, 4D Sedan, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes - Turbo >> Diagnostic Trouble Code Testing >> MOTRONIC 4.3 Control System >> Code 1-3-1: RPM Sensor Signal Absent

Code 1-3-1: RPM Sensor Signal Absent

  1. Turn ignition off. Disconnect RPM sensor. Connect an ohmmeter between RPM sensor connector terminals No. 1 and 2. If ohmmeter shows about 200-500 ohms, go to next step. If ohmmeter does not show 200-500 ohms, replace RPM sensor.
  2. Turn ignition off. Wait 2 minutes. Ensure RPM sensor is disconnected. Connect an ohmmeter between terminal No. 1 (manual transmission) or terminal No. 2 (automatic transmission) at RPM sensor connector at ECM. If ohmmeter reads about zero ohms, go to step 5). If ohmmeter does not read about zero ohms, go to next step.
  3. Turn ignition off. Disconnect RPM sensor connector. Ensure ECM connectors and grounds are clean and tight. Reconnect ECM. Connect an ohmmeter between RPM sensor connector terminal No. 1 (manual transmission) or connector No. 2 (automatic transmission) and ground. If ohmmeter reads about zero ohms, go to next step. If ohmmeter does not read about zero ohms, check wiring between RPM sensor connector No. 1 (manual transmission) or connector No. 2 (automatic transmission) and ECM for an open circuit.
  4. Turn ignition off. Disconnect RPM sensor connector at ECM. Connect an ohmmeter between RPM sensor connector terminals No. 1 and 2. If ohmmeter reads 1500-2000 ohms, go to step 6). If ohmmeter shows infinite resistance, go to next step. If ohmmeter shows about zero ohms, check wiring between RPM sensor connector No. 2 (manual transmission) or No. 1 (automatic transmission) and ECM for a short circuit to ground.
  5. Turn ignition off. Disconnect ECM connector. Ensure all terminals are clean and tight. Repair as necessary. Reconnect ECM. Disconnect RPM sensor. Connect an ohmmeter between RPM sensor connector terminals No. 1 and 2. If ohmmeter reads 1500-2000 ohms, source of code was poor contact at ECM connector. If ohmmeter does not read 1500-2000 ohms, check wiring between RPM sensor and ECM for an open circuit.
  6. Turn ignition on. Disconnect RPM sensor connector. Connect voltmeter between RPM sensor connector terminals. If voltmeter reads 1-2 volts, go to next step. If voltmeter does not read 1-2 volts, check wiring between RPM sensor and ECM for an open circuit or short to voltage.
  7. Turn ignition off. Clean RPM sensor connector. Attempt to start engine. If engine starts, reason for code was poor contact in RPM sensor connector and/or ECM connector. If engine does not start, check connecting flange/flywheel for possible damage and scratches through sensor's holes. If no problem is found on connecting flange/flywheel, test using new RPM sensor.
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