VALVE GP-PILOT 9T6650 - Caterpillar

This procedure requires the measurement of the frequency and duty cycle of the sensor signal. Use the 9U-7330 Digital Multimeter for measuring frequency and duty cycle. To measure frequency, turn the rotary switch to AC volts and press the HZ button once. To measure duty cycle, turn the rotary switch to AC volts and press the HZ button twice. The 6V-7070 Digital Multimeter does not measure frequency or duty cycle. However, the DC voltages are listed in the Sensor Specifications chart as an alternative to measuring the frequency and duty cycle. The 6V-7070 Digital Multimeter can be used for DC voltage measurements.1. Locate the suspect sensor. Identify the sensor wires and connector contacts; see the preceding System Schematic. DO NOT DISCONNECT ANY HARNESS CONNECTORS AT THIS TIME. Use the 7X-1710 Cable Probe (Spoons) to make measurements by probing through the back of the harness connectors.2. CHECK SENSOR SUPPLY VOLTAGE - Turn the ECS to OFF/RESET and then to STOP. Measure the sensor supply DC voltage at the sensor connector (from contact A to contact B on the sensor connector). The voltage should measure from 7.5 to 8.5 DCV.* OK; the voltage is from 7.5 to 8.5 DCV. Go to Step 3.* NOT OK; the voltage is equal to battery positive. The sensor supply is shorted to battery positive in the engine harness. Troubleshoot and repair the engine harness. STOP.* NOT OK; the voltage is not from 7.5 to 8.5 DCV and is not equal to battery positive. Observe the GSC display. a. If a CID 269 fault code is active, go to that procedure in the Diagnostic Fault Troubleshooting section. STOP.b. If a CID 269 fault code is NOT active, then the harness is faulty. Troubleshoot and repair the harness. STOP.3. CHECK SENSOR SIGNAL - The ECS remains in the STOP position. Measure the frequency and duty cycle of the signal at the sensor connector (from contact C to contact B of the sensor connector). Make a note of the measurements. The measured frequency and duty cycle should agree with the values listed in the Sensor Specifications chart.* OK; the measurements agree with the values listed in the Sensor Specifications chart. The sensor is functioning correctly. Go to Step 4.* NOT OK; the measurements DO NOT agree with the values listed in the Sensor Specifications chart. Go to Step 5.4. CHECK ENGINE HARNESS SIGNAL - Measure the frequency and duty cycle of the signal at the GSC harness connector. For the oil pressure signal, measure from contact 8 to contact 31. For the coolant temperature signal, measure from contact 7 to contact 31. The measured frequency and duty cycle should agree with the values measured in Step 3.* OK; the frequency and duty cycle are the same as measured in Step 3. The sensor and harness are functioning correctly. a. If sensor fault codes are still active, the GSC is faulty. Replace the GSC, see the topic Generator Set Control Replacement. STOP.b. If sensor fault codes are