DTC P0122 Throttle Position (TP) Sensor Circuit Low Voltage. Pontiac Sun Runner

For 1990-2009 cars only

Makes 🢒 Pontiac 🢒 1997 🢒 Sun Runner - 4WD (Canada) 🢒 DTC 🢒 DTC P0122 Throttle Position (TP) Sensor Circuit Low Voltage

Circuit Description

The throttle position (TP) sensor contains a potentiometer whose resistance value changes along with the throttle valve position. 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 it into the throttle position. The TP sensor resistance decreases as the throttle valve opening increases. When the TP sensor resistance decreases the voltage being monitored at the PCM will increase. And when the TP sensor resistance increases, because the throttle valve opening is decreasing, the voltage being monitored at the PCM will decrease.

Conditions for Setting the DTC

•	The ignition switch is ON.

•	Low voltage input at the PCM indicated.

•	Above condition is met for at least 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 the diagnostic fails. This information is stored in the Freeze Frame buffer.

Conditions for Clearing the MIL/DTC

•	The MIL turns OFF after three consecutively passing trips without a fault present.

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

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

Diagnostic Aids

A misadjusted TP sensor could cause the malfunction to set. Refer to Throttle Position Sensor Adjustment .

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

•	Backed out terminals.

•	Improper mating of terminals.

•	Broken electrical connector locks.

•	Improperly formed or damaged terminals.

•	Faulty terminal to wire connections.

•	Physical damage to the wiring harness.

•	A broken wire inside the insulation.

•	Corrosion of electrical connections, splices, or terminals.

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

Test Description

Number(s) below refer to the step number(s) on the Diagnostic Table.

The OBD System Check prompts the technician to complete some basic checks and store the freeze frame data on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.

This step determines if DTC P0122 is the result of a hard failure or an intermittent condition.

When the 5 volt reference is jumpered to the TP input circuit, the scan tool parameter should read 99%.

When the TP sensor input circuit is jumpered to battery voltage , the scan tool parameter should read 99%.

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	Start the engine. Run the engine to operating temperature. Turn ON the ignition. Observe the TP sensor parameter on the scan tool while the accelerator pedal is depressed from the idle position to wide open throttle. Does the TP sensor percentage steadily increase within the specified range?	0 to 94%	Go to Step 3	Go to Step 4
3	Turn ON the ignition, leaving the engine OFF. Use the scan tool clear information function. Operate the vehicle within the Freeze Frame conditions as noted. Is a DTC P0122 set?		Go to Step 4	Refer to Diagnostic Aids
4	Disconnect the TP sensor electrical connector. Jumper the 5 volt reference circuit and the TP sensor input circuit together at the TP sensor harness connector. Select the TP sensor on the scan tool. Is the TP sensor percentage greater than the specified value?	90%	Go to Step 10	Go to Step 5
5	Connect a test light between battery voltage and the TP sensor input circuit at the TP sensor harness connector. Monitor the TP sensor on the scan tool. Is TP sensor percentage greater than the specified value?	90%	Go to Step 6	Go to Step 8
6	Turn OFF the ignition. Disconnect the PCM electrical connector at the PCM. Check the 5 volt reference circuit for an open or short. Repair as necessary. Refer to Wiring Repairs in Wiring Systems. Was a repair necessary?	--	Go to Step 14	Go to Step 7
7	Check the 5 volt reference circuit for a poor connection at the TP sensor and the PCM. Replace the terminals as necessary. Was a repair necessary?	--	Go to Step 14	Go to Step 13
8	Turn OFF the ignition. Disconnect the PCM connector at the PCM and check the TP input circuit for an open, or a short to ground. Repair the circuit as necessary. Refer to Wiring Repairs in Wiring Systems. Was a repair necessary?	--	Go to Step 14	Go to Step 9
9	Check the TP sensor input circuit for a poor connection at the PCM. Was a repair necessary?	--	Go to Step 14	Go to Step 13
10	Check TP signal and 5 volt reference circuits for a poor connection at the TP sensor and PCM. Repair the terminals as necessary. Was a repair necessary?	--	Go to Step 14	Go to Step 11
11	Check the TP sensor adjustment. Refer to Throttle Position Sensor Adjustment Repair as necessary. Was a an adjustment necessary?	--	Go to Step 14	Go to Step 12
12	Replace the TP sensor. Refer to Throttle Position Sensor Replacement Is the action complete?	--	Go to Step 14	--
13	Replace the PCM. Refer to Powertrain Control Module Replacement Is the action complete?	--	Go to Step 14	--
14	Perform the scan tool DTC Information function and road test the vehicle within the conditions that set the DTC. Check for DTCs. Review the scan tool data. If no DTCs are set, the repair is complete. Are any DTCs displayed on the scan tool?	--	Go to the applicable DTC Table	System OK