Symptom: P0340-NO CAM SIGNAL AT PCM When Monitored and Set Condition: P0340-NO CAM SIGNAL AT PCM When Monitored: Ignition on. Set Condition: At least 5 seconds have elapsed with crankshaft position sensor signals present but no camshaft position sensor signal. POSSIBLE CAUSES TONE WHEEL/PULSE RING DAMAGED SENSOR GROUND CKT OPEN 5 VOLT SUPPLY CKT OPEN IRREGULAR LAB SCOPE PATTERN OF CMP SIGNAL WIRING HARNESS INTERMITTENT DEFECT STRAY SIGNAL FROM THE CRANKSHAFT POSITION SENSOR CMP SIGNAL CKT OPEN CMP SIGNAL CKT SHORTED TO GROUND CMP SIGNAL CKT SHORTED TO SENSOR GND CKT 5 VOLT SUPPLY CKT SHORTED TO CMP SIGNAL CKT CMP SENSOR DEFECTIVE PCM DEFECTIVE PCM DEFECTIVE CMP SIGNAL CKT SHORTED TO VOLTAGE 145
331 With the DRB in sensors, read the Current CMP Count while cranking the engine. Does the Current CMP Count change while cranking the engine? No Go To 332 Yes Go To 344 332 Turn ignition off. Turn ignition on. Using a voltmeter, measure the 5 volt supply circuit. Is the voltage above 4.5 volts? Yes Go To 333 No the open/high resistance in the 5 volt supply circuit. 333 Turn ignition off. Using an ohmmeter, measure the resistance between the 5 volt supply circuit and the CMP signal circuit at the CMP connector. Yes the 5 volt supply circuit for a short to the CMP signal circuit. No Go To 334 334 Turn ignition off. Turn ignition on. Using a voltmeter, measure the CMP signal circuit at the CMP Sensor connector. Select a conclusion that best matches your voltage measurement. Less than 4.5 volts Go To 335 Between 4.5 and 5.5 volts Go To 339 Greater than 5.5 volts the CMP signal circuit shorted to voltage greater than 5.5 volts. 335 Turn ignition off. Using an ohmmeter, measure the resistance of the CMP signal circuit from the CMP sensor connector to the PCM connector. Yes Go To 336 No the open CMP signal circuit. 146
336 Turn ignition off. Using an ohmmeter, measure the resistance between the CMP Sensor signal circuit and ground. Yes the CMP signal circuit for a short to ground. No Go To 337 337 Turn ignition off. Using an ohmmeter, measure the resistance between the CMP signal circuit and the sensor ground circuit at the CMP connector. Yes the CMP signal circuit for a short to the sensor ground circuit. No Go To 338 338 If there are no potential causes remaining, the Powertrain Control Module is assumed to be defective. Replace the Powertrain Control Module. 339 Turn ignition off. Using an ohmmeter, measure the resistance between the Sensor Ground circuit and ground at the CMP Sensor connector. Yes Go To 340 No Go To 342 340 Turn ignition off. Disconnect and remove the camshaft position sensor. Inspect the tone wheel/pulse ring for physical damage. Make sure that it turns when the engine is cranked. Is the tone wheel/pulse ring free from defects? Yes Go To 341 No /replace tone wheel/pulse ring as necessary. 147
341 Turn ignition off. If there are no potential causes remaining, The Camshaft Position Sensor is assumed to be defective. Replace the Camshaft Position Sensor. 342 Turn ignition off. Using an ohmmeter, measure the sensor ground circuit from the CMP sensor connector to the PCM connector. Yes Go To 343 No the open sensor ground circuit. 343 If there are no potential causes remaining, the Powertrain Control Module is assumed to be defective. Replace the Powertrain Control Module. 344 Turn ignition off. Connect the DRBIII lab scope to the CMP signal circuit. For best results, backprobe at the PCM using Miller special tool #6801. Warning: Keep clear of the engine s moving parts. Start the engine. Observe the lab scope screen while wiggling the wiring harness and connectors. Were there any irregularities in the lab scope pattern? Yes Check harness and connectors carefully. If OK, replace the Camshaft Position Sensor. No Go To 345 345 Turn ignition off. Visually inspect the related wiring harness. Look for any chafed, pierced, pinched, or partially broken wires. Visually inspect the related wire harness connectors. Look for broken, bent, pushed out, or corroded terminals. Note: Refer to any technical service bulletins that may apply. Were any problems found? Yes wiring harness/connectors as necessary. No Go To 346 148
346 Turn ignition off. Connect the DRBIII lab scope to the CKP signal circuit. For best results, backprobe at the PCM using Miller special tool #6801. While observing the lab scope screen, turn ignition on (do not start engine). Look for any pulses generated by the crank sensor. Did the Crankshaft Position Sensor generate any pulses? Yes Replace the Crankshaft Position Sensor. No Test Complete. 149