For 1990-2009 cars

Refer to

#### Cell 21: Engine Data Sensors

Engine Controls Component Views
Information Sensors/Switches Description
Cell 21: EVAP and EGR Controls
Cell 21: Fuel Injectors
OBD II Symbol Description Notice
Handling ESD Sensitive Parts 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 1.0 volt at closed throttle to 4.0 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 that is intermittently above the range of the TP sensor, DTC P1121 will be set.

### Conditions for Running the DTC

The engine is running.

### Conditions for Setting the DTC

• | TP sensor indicates a throttle position voltage intermittently greater than 4.88 volts.

• | The condition is present for longer than 5 seconds.

### Action Taken When the DTC Sets

• | The PCM will not illuminate the malfunction indicator lamp (MIL).

• | The PCM will store conditions which were present when the DTC set as Failure Records data only. This information will not be stored as Freeze Frame data.

### Conditions for Clearing the MIL/DTC

• | A History DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.

• | The DTC can be cleared by using the scan tool Clear Info function.

### Diagnostic Aids

Check for the following conditions:

• | Poor connection at PCM. 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 fault.

Refer to Testing for Continuity , Intermittents and Poor Connections Diagnosis , Repairing Connector Terminals , and Connector Repairs in Wiring Systems.

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.

#### DTC P1121 - TP Sensor Circuit Intermittent High Voltage

Step | Action | Values | Yes | No
--- | --- | --- | --- | ---
1 | Was the Powertrain ON Board Diagnostic System Check performed? | -- | Go to Step 2 | Go to Powertrain On Board Diagnostic (OBD) System Check
2 | Select DTC info, Last Test Fail and note any other DTCs set. Is DTC P0123 also set? | -- | Go to DTC P0123 Throttle Position (TP) Sensor Circuit High Voltage | Go to Step 3
3 | Is DTC P1111, P1115, and/or P1106 also set? | -- | Go to Step 6 | Go to Step 4
4 | Test for a poor sensor ground circuit terminal connection at the TP sensor. Refer to Testing for Continuity , Intermittents and Poor Connections Diagnosis , Repairing Connector Terminals and Connector Repairs in Wiring Systems. Was a problem found? | -- | Go to Step 9 | Go to Step 5
5 | Check the TP signal circuit between the TP sensor connector and the PCM for an intermittent short to voltage. Refer to Testing for Continuity , Intermittents and Poor Connections Diagnosis , Repairing Connector Terminals and Connector Repairs in Wiring Systems.

Was a problem found?

--

Go to Step 10

Go to Step 8

6 | Test for an intermittent short to voltage on the 5 Volt Reference A circuit between the PCM and the following components:

• | MAP sensor

• | EGR valve

• | TP sensor

Refer to Testing for Continuity , Intermittents and Poor Connections Diagnosis , Repairing Connector Terminals and Connector Repairs in Wiring Systems.

Was a problem found?

--

Go to Step 10

Go to Step 7

7 | Test for a poor sensor ground terminal connection at the PCM. Refer to Power and Grounding Component Views in Wiring Systems. Was a problem found? | -- | Go to Step 9 | Go to Step 8
8 | Test for an intermittent open or a faulty splice in the sensor ground circuit. Refer to Testing for Continuity , Intermittents and Poor Connections Diagnosis , Repairing Connector Terminals and Connector Repairs in Wiring Systems. Was a problem found? | -- | Go to Step 10 | Go to Diagnostic Aids
9 | Replace the faulty harness connector terminal for sensor ground circuit. Refer to Testing for Continuity , Intermittents and Poor Connections Diagnosis , Repairing Connector Terminals and Connector Repairs in Wiring Systems. Is the action complete? | -- | Go to Step 11 | --
10 | Repair intermittent open/short circuit in wiring harness as necessary. Refer to Testing for Continuity , Intermittents and Poor Connections Diagnosis , Repairing Connector Terminals and Connector Repairs in Wiring Systems. Is the action complete? | -- | Go to Step 11 | --
11 |

1. Review and record scan tool Fail Records data.
2. Clear DTCs.
3. Operate vehicle within Fail Records conditions as noted.
4. Using a scan tool, monitor Specific DTC info for DTC P1121.

Does scan tool indicate DTC P1121 failed?

--

Go to Step 2

System OK