C - Testing Notes

NOTE: You should enter this Pinpoint Test only when a check for VREF has failed in the sensor Pinpoint Tests (D-Series) or Pinpoint Tests A or QA.

REMEMBER

This Pinpoint Test is intended to diagnose only the following:


- Sensor harness circuits: SIG RTN, VREF

- 3-wire sensors: TP, EVP, PFE, DPFE, MAP, BARO

- Processor assembly


DESCRIPTION

Reference Voltage (VREF) is a positive voltage (above 5.0 volts) that is output by the processor. This consistent voltage is used by all 3-wire sensors.

Signal Return (SIG RTN) is a dedicated ground used by most EEC-IV sensors and some other inputs.