DTC P1121 Throttle Position (TP) Sensor Circuit Intermittent High Voltage. Cadillac Eldorado 2000

For 1990-2009 cars only

Makes 🢒 Cadillac 🢒 2000 🢒 Eldorado 🢒 Engine 🢒 Engine Controls - 4.6L 🢒 DTC P1121 Throttle Position (TP) Sensor Circuit Intermittent High Voltage

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Circuit Description

The throttle position (TP) sensor is potentiometer used to indicate the amount of throttle opening. The powertrain control module (PCM) supplies the TP sensor with a 5 volt reference and a ground. The TP sensor provides a signal voltage to the PCM relative to throttle blade angle. With the throttle closed, the signal voltage is low. However, the signal voltage increases as the throttle opens. During normal operation, TP signal voltage will vary from below 1 volt at idle to above 4 volts at wide open throttle (WOT). The TP signal is one of the most important sensor inputs used by the PCM for controlling fuel and most of the PCM-controlled outputs. If the PCM detects an intermittently high TP sensor signal, DTC P1121 will set.

Conditions for Running the DTC

The engine is running.

Conditions for Setting the DTC

•	The TP sensor signal voltage is intermittently greater than 4.7 volts.

•	The condition exists for less than 1 second.

Action Taken When the DTC Sets

•	The PCM will illuminate the malfunction indicator lamp (MIL) the first time the malfunction is detected.

•	The PCM will store conditions which were present when the DTC set as Freeze Frame and Fail Records data.

Conditions for Clearing the MIL/DTC

•	The PCM will turn the MIL OFF after the third consecutive trip in which the diagnostic has been run and passed.

•	The 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 DTC Information function.

Diagnostic Aids

If the condition is intermittent, refer to Intermittent Conditions in Symptoms.

Step

Action

Value(s)

Yes

Did you perform the Powertrain On Board Diagnostic (OBD) System Check?

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

Are any other DTCs also set?

Go to Diagnostic Trouble Code (DTC) List/Type

Go to Step 3

Test the 5V reference A circuit for an intermittent short to voltage.
If a condition is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 6

Go to Step 4

Test the TP sensor signal circuit for the following intermittent condition(s):

•	Short to the 5V reference A circuit

•	Short to voltage

If a condition is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 6

Go to Step 5

Test the TP sensor ground circuit for the following intermittent condition(s):

•	An open circuit

•	Poor connections at the PCM or the TP sensor, refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

If a condition is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 6

Go to Diagnostic Aids

Review and record the scan tool Fail Records data.
Clear the DTCs.
Operate the vehicle within the parameters listed in the Conditions for Running the DTC.
With the scan tool, monitor the Specified DTC Information for DTC P1121.

Does the scan tool indicate that DTC P1121 passed?

System OK

Go to Step 2