Circuit Description
The throttle body assembly contains 2 throttle position (TP) sensors. The TP sensors are mounted to the throttle body assembly and are not serviceable. The TP sensors provide a signal voltage that changes relative to throttle blade angle. The engine control module (ECM) supplies the TP sensors with a common 5-volt reference circuit, a common low reference circuit, and 2 independent signal circuits.
The TP sensors have opposite functionality. The TP sensor 1 signal voltage increases from below 1 volt at idle to above 4 volts at wide open throttle (WOT). The TP sensor 2 signal voltage decreases from above 4 volts at idle to below 1 volt at WOT.
If the ECM detects TP sensor 1 signal voltage is too low, this DTC sets.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0122 Throttle Position (TP) Sensor 1 Circuit Low Voltage
Conditions for Running the DTC
| • | The ignition is ON, with the engine OFF, or the engine is running. |
| • | The ignition 1 voltage is more than 7 volts. |
| • | DTC P0122 runs continuously once the above conditions are met. |
Conditions for Setting the DTC
The ECM detects the TP sensor 1 signal voltage is less than 0.18 volts for more than 4 seconds.
Action Taken When the DTC Sets
| • | The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails. |
| • | The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records. |
Conditions for Clearing the MIL/DTC
| • | The control module turns OFF the malfunction indicator lamp (MIL) after 4 consecutive ignition cycles that the diagnostic runs and does not fail. |
| • | A current DTC, last test failed, clears when the diagnostic runs and passes. |
| • | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic. |
| • | Clear the MIL and the DTC with a scan tool. |
Diagnostic Aids
| • | Use the J 35616-A/BT-8637 Connector Test Adapter Kit for any test that requires probing the ECM harness connector or a component harness connector. |
| • | The lower connector of the ECM is connector C1 and the upper connector of the ECM is connector C2. Refer to Front of Vehicle/Engine Compartment Component Views. |
| • | If there is a condition with the TP sensors, the ECM defaults to reduced power mode for the entire ignition cycle, even if the condition is corrected. |
| • | For an intermittent condition, refer to Intermittent Conditions. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step verifies that a condition exists.
-
The TP sensors share a 5-volt reference circuit. If both DTCs P0122 and P0222 set, test for a condition in the 5-volt reference circuit.
-
The ECM produces a measurable steady-state amperage that provides the 5-volt reference to the TP sensors. If the amperage on the 5-volt reference circuit is less than 50 mA, test the 5-volt reference circuit for an open or a high resistance.
-
This step tests the signal 1 circuit of the TP sensor. If the TP sensor 1 voltage parameter is not 4.8-5.2 volts, test for a condition in the signal 1 circuit.
Step | Action | Values | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Component Connector End Views | ||||||||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |||||||
Is the voltage less than the specified value? | 0.18 V | Go to Step 4 | Go to Step 3 | |||||||
3 |
Did the DTC fail this ignition? | -- | Go to Step 4 | Go to Diagnostic Aids | ||||||
Observe the DTC information with a scan tool. Did DTC P0222 also set? | -- | Go to Step 5 | Go to Step 6 | |||||||
Caution: Refer to Disengaging Connectors Caution in the Preface section. Is the amperage more than the specified value? | 50 mA | Go to Step 9 | Go to Step 7 | |||||||
Caution: Refer to Disengaging Connectors Caution in the Preface section. Is the voltage within the specified range? | 4.8-5.2 V | Go to Step 9 | Go to Step 8 | |||||||
7 |
Note: The 5-volt reference circuits are internally connected within the controller. Other sensors that share the 5-volt reference circuit may also have DTCs set. Disconnecting a sensor on the shared 5-volt reference circuit may isolate a shorted sensor. Review the electrical schematic and diagnose the shared circuits and sensors. Test the 5-volt reference circuit of the TP sensor and all shared 5-volt reference circuits for one of the following conditions:
Refer to Circuit Testing and Wiring Repairs. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 10 | ||||||
8 | Test the signal 1 circuit of the TP sensor for one of the following conditions:
Refer to Circuit Testing and Wiring Repairs. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 10 | ||||||
9 | Test for an intermittent and for a poor connection at the throttle body assembly. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 11 | ||||||
10 | Test for an intermittent and for a poor connection at the ECM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 12 | ||||||
11 | Replace the throttle body assembly. Refer to Throttle Body Assembly Replacement. Did you complete the replacement? | -- | Go to Step 13 | -- | ||||||
12 | Replace the ECM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 13 | -- | ||||||
13 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 14 | ||||||
14 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | |||||||
