Circuit Description
The throttle position (TP) sensor incorporates 2 ratiometric TP sensors into one housing. TP sensor 1 and TP sensor 2 each have a 5-volt reference circuit supplied by the throttle actuator control (TAC) module. The TAC module supplies each TP sensor with a low reference circuit. Each TP sensor supplies the TAC module with a signal voltage that is proportional to the throttle blade position. Both of the TP signal voltages increase as the throttle blade is opened. The TP sensor 1 and the accelerator pedal position (APP) sensor 1 share a 5-volt reference circuit that is bussed within the TAC module. The TP sensor 2 and the APP sensor 2 share a 5-volt reference circuit that is also bussed within the TAC module. When this DTC sets, the Reduced Engine Power indicator will be displayed.
This DTC incorporates the following diagnostic tests:
| • | The TP sensor 1 signal circuit voltage out of range |
| • | The throttle blade minimum position for the TP sensor 1 out of range |
| • | The 5-volt reference of the TP sensor 1 tests out of range |
If the PCM detects one or more of the TP sensor 1 tests are out of range, DTC P0120 sets.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0120 Throttle Position (TP) Sensor 1 Circuit
Conditions for Running the DTC
| • | DTCs P2108 or U0107 are not set. |
| • | The ignition switch is in the Crank or Run position. |
| • | The ignition voltage is more than 5.23 volts. |
| • | The TP sensor 1 signal voltage test runs continuously once the above conditions are met. |
| • | The throttle blade minimum position for the TP sensor 1 test runs once when the ignition is turned ON and the above conditions are met. |
| • | The 5-volt reference of the TP sensor 1 voltage test runs continuously once the above conditions are met. |
Conditions for Setting the DTC
| • | The TP sensor 1 voltage is less than 0.38 volts or more than 4.5 volts for more than 0.1 second. |
| OR |
| • | The TP sensor 1 minimum throttle blade position is less than 0.38 volts or more than 0.71 volts for less than 1 second. |
| OR |
| • | The 5-volt reference circuit of the TP sensor 1 is shorted to ground for more than 0.01 second. |
| OR |
| • | The 5-volt reference circuit of the TP sensor 1 is less than 4.54 volts or more than 5.21 volts for more 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
| • | Inspect the TAC module connectors for signs of water intrusion. When this occurs, multiple DTCs could be set with no circuit or component conditions found during diagnostic testing. |
| • | When the TAC module detects a condition within the TAC system, more than one TAC system related DTC may set. This is due to the many redundant tests run continuously on this system. Locating and repairing one individual condition may correct more than one DTC. Disconnecting components during testing may set additional DTCs. Keep this in mind when reviewing the stored information, Capture Info. |
| • | If this DTC is determined to be intermittent, refer to Testing for Intermittent Conditions and Poor Connections . |
Test Description
The number below refers to the step number on the diagnostic table.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Controls Component Views or Powertrain Control Module Connector End Views | ||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |
2 |
Is the TP sensor 1 voltage within the specified range? | 0.38-0.71 V | Go to Step 5 | Go to Step 3 |
3 |
Is the TP sensor 2 voltage within the specified range? | 0.28-0.81 V | Go to Step 9 | Go to Step 4 |
4 | Is DTC U0107 also set? | -- | Go to Step 9 | |
5 |
Is the TP sensor 1 voltage parameter more than the specified value? | 4.5 V | Go to Step 9 | Go to Step 6 |
6 |
Did you find and correct the condition? | -- | Go to Step 32 | Go to Step 7 |
7 |
Did you find and correct the condition? | -- | Go to Step 32 | Go to Step 8 |
8 |
Does the scan tool indicate this DTC failed this ignition? | -- | Go to Step 27 | Go to Diagnostic Aids |
9 |
Is the voltage within the specified range? | 3.94-6.06 V | Go to Step 14 | Go to Step 10 |
10 |
Did you find and correct the condition? | -- | Go to Step 32 | Go to Step 11 |
11 | Test the TP sensor 1 signal circuit for an open or high resistance with a DMM. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 32 | Go to Step 12 |
12 | Test the TP sensor 1 signal circuit for a short to ground with a DMM. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 32 | Go to Step 13 |
13 |
Did you find and correct the condition? | -- | Go to Step 32 | Go to Step 28 |
14 | Measure the voltage from the TP sensor 1 5-volt reference circuit to a good ground with a DMM. Refer to Circuit Testing . Is the voltage within the specified range? | 4.54-5.21 V | Go to Step 24 | Go to Step 15 |
15 | Is the voltage more than the specified value? | 5.21 V | Go to Step 16 | Go to Step 18 |
16 |
Did you find and correct the condition? | -- | Go to Step 32 | Go to Step 17 |
17 |
Did you find and correct the condition? | -- | Go to Step 32 | Go to Step 22 |
18 | Disconnect the APP sensor. Is the voltage less than the specified value? | 4.54 V | Go to Step 19 | Go to Step 30 |
19 |
Did you find and correct the condition? | -- | Go to Step 32 | Go to Step 20 |
20 | Test the TP sensor 1 5-volt reference circuit for a short to ground with a DMM. Did you find and correct the condition? | -- | Go to Step 32 | Go to Step 21 |
21 | Test the APP sensor 1 5-volt reference circuit for a short to ground with a DMM. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 32 | Go to Step 22 |
22 | Test for a short between the TP sensor 1 5-volt reference circuit and all other TAC module circuits with a DMM. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 32 | Go to Step 23 |
23 | Test for a short between the APP sensor 1 5-volt reference circuit and all other TAC module circuits with a DMM. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 32 | Go to Step 28 |
24 |
Is the TP sensor 1 parameter near the specified value? | 0 V | Go to Step 26 | Go to Step 25 |
25 |
Did you find and correct the condition? | -- | Go to Step 32 | Go to Step 28 |
26 | Inspect for an intermittent and for a poor connection at the throttle body harness connector. Refer to Testing for Intermittent Conditions and Poor Connections and Repairing Connector Terminals . Did you find and correct the condition? | -- | Go to Step 32 | Go to Step 29 |
27 | Inspect for an intermittent and for a poor connection at the APP sensor harness connector. Refer to Testing for Intermittent Conditions and Poor Connections and Repairing Connector Terminals . Did you find and correct the condition? | -- | Go to Step 32 | Go to Step 30 |
28 | Inspect for an intermittent and for a poor connection at the TAC module harness connector. Refer to Testing for Intermittent Conditions and Poor Connections and Repairing Connector Terminals . Did you find and correct the condition? | -- | Go to Step 32 | Go to Step 31 |
29 | Replace the throttle body assembly. Refer to Throttle Body Assembly Replacement . Did you complete the replacement? | -- | Go to Step 32 | -- |
30 | Replace the APP sensor. Refer to Accelerator Pedal Position Sensor Replacement . Did you complete the replacement? | -- | Go to Step 32 | -- |
31 | Replace the TAC module. Refer to Electronic Throttle Actuator Control Module Replacement . Did you complete the replacement? | -- | Go to Step 32 | -- |
32 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 33 |
Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | ||
