HE74 - Measure VREF Voltage at DPFE Sensor Harness Connector

- DPFE sensor disconnected.

- Key On, Engine Off.

- Measure voltage between the sensor VREF circuit and SIG RTN circuit at the DPFE sensor vehicle harness connector.

- Is VREF voltage between 4.0 and 6.0 volts?

YES -- RECONNECT DPFE sensor. GO to HE75. HE75 - Check DPFE Sensor Output - Apply Vacuum With Hand Pump

NO -- VREF voltage is out of range. GO to Pinpoint Test Step C1. C1 - Check Battery Voltage