For 1990-2009 cars
Engine Controls Components
Engine Data Sensors
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice

### 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 less than 1.0 volt at Closed Throttle to more than 4.0 volts at Wide Open Throttle (WOT). If the powertrain control module (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

TP sensor intermittently indicates a throttle position signal 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

Inspect for the following conditions:

Important: Remove any debris from the connector surfaces before servicing a component. Inspect the connector gaskets when diagnosing or replacing a component. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion.

• | Faulty terminal connection--Inspect the harness connectors for the following conditions:

- | Backed out terminals

- | Improper mating

- | Broken locks

- | Improperly formed or damaged terminals

- | Faulty terminal to wire connection--Use a corresponding mating terminal to test for proper tension. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

• | Damaged harness--Inspect the wiring harness for damage.

| If the harness inspection does not reveal a problem, observe the display on the scan tool while moving connectors and wiring harnesses related to the sensor. A change in the scan tool display may indicate the location of the fault. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

• | Clean and secure connections at the PCM and the engine grounds.

If the DTC is determined to be intermittent, reviewing the Failure Records can be useful in determining when the DTC was last set.

### Test Description

The numbers below refer to the step numbers on the diagnostic table:

1. This test will determine an intermittent faulty TP sensor utilizing the DMM MIN MAX 100-millisecond capture mode.

Step | Action | Values | Yes | No
--- | --- | --- | --- | ---
1 | Did you perform the Powertrain On Board Diagnostic (OBD) System Check? | -- | Go to Step 2 | Go to Powertrain On Board Diagnostic (OBD) System Check
2 | Does the scan tool indicate P0123 also set? | -- | Go to DTC P0123 Throttle Position (TP) Sensor Circuit High Voltage | Go to Step 3
3 | Test each 5-volt reference circuits for an intermittent short to voltage.

1. Turn OFF the ignition.
2. Disconnect the TP sensor.
3. Connect a DMM between the TP sensor 5 volt reference circuit at the TP harness connector and ground.
4. Turn ON the ignition.
5. Lightly touch and wiggle the related engine wiring harnesses and connectors for all 5-volt reference circuits while observing the voltage. Any change in voltage indicates the area where a short to voltage may be found. Refer to Circuit Testing and Wiring Repairs and Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 10

Go to step 4

4 | Test the TP sensor signal circuit for an intermittent short to voltage.

1. Turn OFF the ignition.
2. Connect a DMM between the TP sensor signal circuit at the TP harness connector and ground.
3. Turn ON the Ignition.
4. Lightly touch and wiggle the related engine wiring harnesses and connectors while observing voltage. Any change in voltage indicates the area where a short to voltage may be found. Refer to Circuit Testing and Wiring Repairs and Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 10

Go to Step 5

5 | Test the TP sensor ground circuit for an intermittent open or high resistance.

1. Turn OFF the ignition for 30 seconds.
2. Connect a DMM between the TP sensor ground circuit at the TP harness connector and ground.
3. Lightly touch and wiggle the related engine wiring harnesses and connectors while observing resistance. Any change in resistance indicates the area where an open or high resistance may be found. Refer to Circuit Testing and Wiring Repairs and Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 10

Go to Step 6

6 | 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? | -- | Go to Step 10 | Go to Step 7
7 | 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 Step 10 | Go to step 8
8 |

1. Connect two jumper wires at the TP sensor, one at the signal terminal, one at the 5-volt reference terminal.
2. With a DMM set to 40k ohms scale connect the DMM to the jumper wires.
3. Ensure a good, proper connection at the TP sensor and DMM test leads.
4. Press the MIN MAX button on the DMM.
5. Slowly depress the accelerator pedal to Wide Open Throttle (WOT) and back to the closed throttle position several times.
6. Press the MIN MAX button and record the MAX reading.
7. Press the MIN MAX button again and record the MIN reading.
8. Remove the jumper wire at the 5-volt reference terminal and connect it to the ground terminal and repeat steps 2 through 7.

Did you record a MAX value of OL or a record a MIN value of 0 ohms in either test?

--

Go to step 9

Go to Diagnostic Aids

9 | Replace the TP sensor. Refer to Throttle Position Sensor Replacement . Did you complete the replacement? | -- | Go to step 10 | --
10 |

1. Use a scan tool in order to clear the DTCs.
2. Turn OFF the ignition for 30 seconds.
3. Start the engine.
4. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC run and pass?

--

System OK

Go to Step 2