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. TP sensor 1 signal voltage decreases from above 4 volts at idle to below 1 volt at wide open throttle (WOT). TP sensor 2 signal voltage increases from below 1 volt at idle to above 4 volts 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
| • | DTCs P0601, P0602, P0603, P0604, P0606, P0607, P0641, P0651 are not set. |
| • | The ignition is ON, with the engine OFF, or the engine is operating. |
| • | The ignition 1 voltage is more than 5.23 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 0.35 volts for less than 1 second.
Action Taken When the DTC Sets
| • | The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails. |
| • | The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame and/or the Failure Records. |
| • | The control module commands the TAC system to operate in the Reduced Engine Power mode. |
| • | A message center or an indicator displays Reduced Engine Power. |
| • | Under certain conditions the control module commands the engine OFF. |
Conditions for Clearing the MIL/DTC
| • | The control module turns OFF the malfunction indicator lamp (MIL) after 3 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 Connector Test Adapter Kit for any test that requires probing the ECM harness connector or a component harness connector. |
| • | 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 Testing for Intermittent Conditions and Poor Connections. |
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: Engine Control Module Connector End Views or Engine Controls Connector End Views | ||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |
Is the voltage less than the specified value? | 0.35 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 | |
Notice: Refer to Disengaging Connectors Notice in the Preface section. Is the amperage more than the specified value? | 50 mA | Go to Step 9 | Go to Step 7 | |
Notice: Refer to Disengaging Connectors Notice 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 |
Important: 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 an open, a short to ground, or for high resistance. 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 a short to ground, an open, or for high resistance. 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 engine control module (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 Installation . 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 | |
