Circuit Description
The throttle position (TP) sensor circuit provides a voltage signal that changes relative to throttle blade angle. The signal voltage will vary from 1 volt at closed throttle to more than 4 volts at wide open throttle (WOT). The TP signal is one of the most important inputs used by the PCM for fuel control and most of the PCM-controlled outputs. If the PCM detects a TP signal voltage that is intermittently more than the range of the TP sensor, DTC P1121 will be set.
Conditions for Running the DTC
The ignition is ON.
Conditions for Setting the DTC
The TP sensor intermittently indicates a throttle position signal of more than 4.9 volts.
Action Taken When the DTC Sets
The PCM stores conditions which were present when the DTC set as Failure Records only. This information will not be stored as Freeze Frame Records.
Conditions for Clearing the MIL/DTC
| • | The DTC becomes history when the conditions for setting the DTC are no longer present. |
| • | The history DTC clears after 40 malfunction free warm-up cycles. |
| • | The PCM receives a clear code command from the scan tool. |
Diagnostic Aids
Check for the following conditions:
| • | Poor connection at the PCM or the TP sensor |
| Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection. |
| • | Damaged harness |
| Inspect the wiring harness for damage. |
| • | If the harness appears to be OK, observe the throttle position display on the scan tool while moving connectors and wiring harnesses related to the TP sensor. A change in the display will indicate the location of the malfunction. |
If DTC P1121 cannot be duplicated, reviewing the Fail Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set occurs. This may assist in diagnosing the condition.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On Board Diagnostic (OBD) System Check? | -- | ||
2 |
Important: If DTC P1635 5 Volt Reference Circuit is set, perform that diagnostic first. Select Diagnostic Trouble Codes (DTCs) and note if any other DTCs are set. Is DTC P0123 also set? | -- | Go to DTC P0123 Throttle Position (TP) Sensor Circuit High Voltage | |
3 | Is DTC P1111, P1115, and/or P1106 also set? | -- | ||
4 | Test all 5 volt reference A circuits and connected components for an intermittent short to voltage. Refer to Wiring Repairs in Wiring Systems . Did you find and correct the condition? | -- | Go to Diagnostic Aids | |
5 | Test the signal circuit of the TP sensor for an intermittent short to voltage. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | ||
6 | Test the ground circuit of the TP sensor for an intermittent open. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | ||
7 | Inspect for faulty connections at the harness connector of the TP sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | ||
8 | Inspect for faulty connections at the harness connector of the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems . Did you find and correct the condition? | -- | Go to Diagnostic Aids | |
9 |
Does scan tool indicate DTC P1121 failed? | -- | System OK |
