Diagnostic Aids

Tech 1 displays throttle position in volts. With closed throttle, ignition on, or at idle, voltage should be .20-.74 volt. If voltage is not as specified, replace TP sensor. On 3.8L, an open in sensor ground circuit will cause Codes P0112, P0712, P0117 and P0123 to set. Check for:

• Poor Connection Or Damaged Harness:  Inspect PCM harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection, and damaged harness.
• Intermittent Test:  Monitor TP sensor voltage display on Tech 1 while moving related connectors and wiring harness. If failure is induced, display will change. This may assist in isolating the location of the malfunction.
• TP Sensor Scaling:  Observe TP sensor voltage display while depressing accelerator pedal with engine stopped and ignition on. Display should vary from closed throttle TP sensor voltage when throttle is closed (.20-.74 volt) to greater than 4 volts when throttle is held at WOT position.

Fig 1: Code P0123 Schematic (3.8L "U" Body) Throttle Position Sensor

Fig 2: Code P0123 Flow Chart (3.8L "U" Body) Throttle Position Sensor

Fig 3: Code P0123 Flow Chart