C2 - Check VREF Voltage

- Key "ON", engine "OFF".

- Breakout box installed, Powertrain Control Module (PCM) connected.

- Measure voltage between test pin 26 and test pin 46 at the breakout box.

- What is the voltage?

Greater than 6.0 volts: Go to C4. C4 - Check For Excess Voltage On VREF Circuit

Less than 4.0 volts: Go to C5. C5 - Check For Shorted Throttle Position Sensor

Between 4.0 and 6.0 volts: Go to C3. C3 - Check VREF and SIG RTN Circuits For Continuity