DTC P0122 Throttle Position (TP) Sensor Circuit Low Voltage. Cadillac Eldorado 2000

For 1990-2009 cars only

Makes 🢒 Cadillac 🢒 2000 🢒 Eldorado 🢒 Engine 🢒 Engine Controls - 4.6L 🢒 DTC P0122 Throttle Position (TP) Sensor Circuit Low Voltage

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Circuit Description

The throttle position (TP) sensor is potentiometer used to indicate the amount of throttle opening. The 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 excessively low TP sensor signal, DTC P0122 will set.

Conditions for Running the DTC

The ignition is in the run position.

Conditions for Setting the DTC

•	The TP sensor signal voltage is less than 0.25 volts.

•	The condition exists for less than 1 second.

Action Taken When the DTC Sets

•	The PCM illuminates the malfunction indicator lamp (MIL) during the second consecutive trip in which the diagnostic test runs and fails.

•	The PCM stores the conditions present when the DTC set as Freeze Frame/Failure Records data.

Conditions for Clearing the MIL/DTC

•	The PCM will turn the MIL OFF after the third consecutive trip in which the diagnostic runs and passes.

•	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

Values

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

Turn ON the ignition, with the engine OFF.
With the throttle closed, monitor the TP sensor display with a scan tool.

Is the TP sensor below the specified value?

0.25V

Go to Step 3

Go to Diagnostic Aids

Is DTC P1635 also set?

Go to DTC P1635 5 Volt Reference Circuit

Go to Step 4

Turn OFF the ignition.
Disconnect the TP sensor connector.
Install the scan tool.
Turn ON the ignition, with the engine OFF.
Connect a jumper between the 5V Reference A and TP signal circuits in harness connector.
Observe the TP sensor display on the scan tool.

Does scan tool indicate a voltage near the specified value?

Go to Step 8

Go to Step 5

Leave the TP sensor disconnected.
Leave the ignition ON, with the engine OFF.
With the DMM, measure the voltage between the 5V Reference A circuit and ground.

Does the DMM indicate a voltage near the specified value?

Go to Step 6

Go to Step 7

Test the TP sensor signal circuit for the following conditions:

•

An open

•	A short to chassis or sensor ground

•	Poor connections at the PCM

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

Did you find and correct a condition?

Go to Step 11

Go to Step 10

Test the 5V Reference circuit for an open or poor connections at the PCM. Refer to Circuit Testing or Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
If a condition is found, repair as necessary. Refer to Wiring Repairs or Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 11

Go to Step 10

Inspect for poor connections at 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 Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 11

Go to Step 9

Replace the TP sensor. Refer to Throttle Position Sensor Replacement .

Is the action complete?

Go to Step 11

Important: The replacement PCM must be programmed.

Replace the PCM. Refer to Powertrain Control Module Replacement/Programming .

Is the action complete?

Go to Step 11

Review and record the scan tool Fail Records data.
Clear the DTCs.
Operate the vehicle the parameters listed in the Conditions for Running the DTC.
With the scan tool, monitor the Specific DTC Information for DTC P0122 until the test runs.

Does the scan tool indicate that DTC P0122 passed?

System OK

Go to Step 2