Circuit Description
The powertrain control module (PCM) supplies a 5-volt reference signal and a ground to the sensor. the throttle position (TP) sensor sends a voltage signal back to the PCM relative to throttle blade opening. The TP sensor signal voltage will vary from 0.45 volts at closed throttle to over 4.5 volts at wide open throttle. The TP sensor is one the most important sensors in the control of fuel delivery.
Conditions for Setting
| • | The manifold absolute pressure (MAP) sensor reads less than 37.2 kPa. |
| • | If the TP sensor reads less than 0.16 volts for 50 out of 100 sample counts. |
Action Taken
| • | The malfunction indicator lamp (MIL) will illuminate. |
| • | The TP angle will default to 0 percent when the vehicle speed is less than 2 mph and 10 percent when the vehicle speed is greater than 2 mph. The scan tool will display the defaulted value. |
Conditions for Clearing the MIL/DTC
| • | The MIL will turn OFF after passing three consecutive diagnostic tests. |
| • | A history DTC will clear after 40 consecutive ignition cycles have occurred without a fault. |
| • | History and current DTCs can be cleared by using a scan tool. |
Diagnostic Aids
If a DTC P0122 cannot be duplicated, the information included in the Freeze Frame data can be useful in determining how many ignition cycles have passed since last set. If the DTC occurs intermittently, use the DTC P1122 diagnostic chart to help isolate the problem.
Test Description
The number below refers to the step number on the diagnostic table.
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The TP sensor has an auto zeroing feature. If the voltage reading is between 0.2-0.9 volts, the PCM will assume the TP sensor is at a closed throttle position.
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Simulates a DTC P0123. If the PCM recognizes the high voltage signal, then the PCM and wiring are OK.
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This simulates a high voltage signal which will identify an open in the signal circuit.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||
1 | Was the On-Board Diagnostic (OBD) System Check perform? | -- | Go to Step 2 | |
Is the TP sensor voltage below the specified value? | 0.2 V | Go to Step 4 | Go to Step 3 | |
3 |
Is the TP sensor voltage below the specified value? | 0.2 V | Go to Step 4 | Go to Diagnostic Aids |
Is the TP sensor voltage greater than the specified value? | 4 V | Go to Step 10 | Go to Step 5 | |
Is the TP sensor voltage greater than the specified value? | 4 V | Go to Step 6 | Go to Step 8 | |
6 |
Was a repair necessary? | -- | Go to Step 7 | |
7 | Inspect the 5-volt reference circuit for a poor connection at the PCM. Replace terminals if necessary. Was a repair necessary? | -- | Go to Step 11 | |
8 |
Was a repair necessary? | -- | Go to Step 9 | |
9 |
Is the action complete? | -- | Go to Step 11 | |
10 | Replace the TP sensor. Is the action complete? | -- | -- | |
11 | Replace the PCM. Is the action complete? | -- | -- | |
