DTC P0122 Throttle Position (TP) Sensor Circuit Low Voltage. Pontiac Firefly (Canada) 2000

For 1990-2009 cars only

Makes 🢒 Pontiac 🢒 2000 🢒 Firefly (Canada) 🢒 DTC 🢒 DTC P0122 Throttle Position (TP) Sensor Circuit Low Voltage

Engine Controls Components
Cell 21: Engine Data Sensors
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice

Circuit Description

The throttle position (TP) sensor contains a potentiometer whose resistance value changes as the throttle valve position changes. The powertrain control module (PCM) provides a 5 volt reference voltage to the TP sensor. The PCM reads the voltage across the TP sensor and converts the voltage into a throttle angle. The TP sensor resistance decreases as the throttle-valve opening increases, and increases as the throttle-valve opening decreases. The TP sensor voltage increases as the throttle-valve opening increases.

Conditions for Running the DTC

The ignition is ON.

Conditions for Setting the DTC

•	A low voltage input, with a throttle opening of less than 2 percent, is indicated at the PCM.

•	The above condition is present for at least 0.5 seconds.

Action Taken When the DTC Sets

•	The PCM illuminates the malfunction indicator lamp (MIL).

•	The PCM records the operating conditions at the time that the diagnostic fails. This information is stored in the Freeze Frame buffer.

•	The PCM enters the Fail-Safe Function and assumes the throttle angle is 20 degrees.

Conditions for Clearing the DTC

•	The MIL turns OFF after 3 consecutive trips during which the diagnostic runs, and a fault is not detected.

•	A History DTC clears after 40 consecutive warm-up cycles without a fault.

•	Use the Clear DTC Information function of the scan tool, or disconnect the PCM battery feed in order to clear the DTC.

Diagnostic Aids

Check for any of the following conditions:

•

Check the resistance of the TP sensor. TP sensor resistance between terminals 1 and 2 should be between 2.5-6.0k ohms. TP sensor resistance between terminals 1 and 3 should be between 100 ohms and 20k ohms. Replace the TP sensor if the measured resistance is not within the specified values. Refer to Throttle Position Sensor Replacement .

•	Check for an open in the reference circuit if a DTC P0107 and P0122 are set together.

•	A faulty electrical connection to the PCM.

An intermittent malfunction may be caused by a fault in the TP sensor electrical circuit. Inspect the wiring harness and the components for any of the following conditions:

•	Backed out terminals

•	Incorrect mating of terminals

•	Broken electrical connector locks

•	Incorrectly formed terminals or damaged terminals

•	Faulty terminal-to-wire connections

•	Physical damage to the wiring harness

•	A broken wire inside the insulation

•	Corrosion of electrical connections, of splices, or of terminals.

If DTC P0122 cannot be duplicated, the Freeze Frame data can be useful in determining the vehicle operating conditions when the DTC first set.

Test Description

The numbers below refer to the step numbers in the diagnostic table.

The Powertrain OBD system check prompts the technician to complete some basic checks, and to save the freeze frame data on the scan tool if applicable. This creates an electronic copy of the data that was taken when the fault occurred. The scan tool saves the information for later reference.

This step determines if a fault is present. The vehicle must be at operating temperature.

This step checks the reference voltage at the TP sensor.

This step checks the circuit that supplies the reference voltage to the TP sensor.

Step	Action	Value(s)	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	Operate the engine until normal operating temperatures are reached. Turn ON the ignition, leaving the engine OFF. Install a scan tool. With the throttle in a closed position, select the TP angle parameter on the scan tool. Is the TP sensor percentage at the specified value or below the specified value?	2%	Go to Step 4	Go to Step 3
3	Turn ON the ignition, leaving the engine OFF. Clear the scan tool information. Operate the vehicle within the Freeze Frame conditions as noted. Is the TP sensor percentage at the specified value or below the specified value?	2%	Go to Step 4	Go to Diagnostic Aids
4	Disconnect the TP sensor electrical connector. Measure the voltage from the haraness side of the TP sensor signal circuit to ground with a DMM. Is the TP sensor signal voltage within the specified value?	4-5 V	Go to Step 5	Go to Step 7
5	Measure the voltage from the harness side of the 5 volt reference circuit to ground with the DMM. Is the voltage near the specified value?	5.0 V	Go to Step 10	Go to Step 6
6	Turn OFF the ignition. Disconnect the PCM electrical connectors. Check the 5 volt reference circuit for an open or for a short to ground. Repair as necessary. Refer to Wiring Repairs in Wiring Systems. Was a repair necessary?	--	Go to Step 12	Go to Step 8
7	Turn OFF the ignition. Disconnect the PCM electrical connectors. Check the TP sensor signal circuit for a short to ground. Repair as necessary. Refer to Wiring Repairs in Wiring Systems. Was a repair necessary?	--	Go to Step 12	Go to Step 9
8	Check the 5 volt reference circuit for a poor connection at the PCM or at the TP sensor. Repair as necessary. Refer to Wiring Repairs in Wiring Systems. Was a repair necessary?	--	Go to Step 12	Go to Step 11
9	Check the TP sensor signal circuit for a poor connection at the PCM or at the TP sensor. Repair as necessary. Refer to Wiring Repairs in Wiring Systems. Was a repair necessary?	--	Go to Step 12	Go to Step 11
10	Replace the TP sensor. Refer to Throttle Position Sensor Replacement . Is the action complete?	--	Go to Step 12	--
11	Replace the PCM. Is the action complete?	--	Go to Step 12	--
12	Perform the Clear DTC information function on the scan tool, and road-test the vehicle within the Freeze Frame conditions which set the DTC. Review the scan tool data, and check the data for DTCs. The repair is complete if no DTCs are displayed. Are any DTCs displayed on the scan tool?	--	Go to the applicable DTC table	System OK