DTC P0122 Throttle Position (TP) Sensor Circuit Low Voltage. Buick Regal 2000

For 1990-2009 cars only

Makes 🢒 Buick 🢒 2000 🢒 Regal 🢒 Body and Accessories 🢒 Wiring Systems 🢒 DTC P0122 Throttle Position (TP) Sensor Circuit Low Voltage

Engine Controls Components
A/C Pressure Switch, Throttle Position Sensor, MAP Sensor, ECT Sensor and IAT Sensor
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 less than 1 volt at Closed Throttle to about 4 volts at Wide Open Throttle (WOT). The TP signal is one of the most important inputs used by the powertrain control module (PCM) for fuel control and most of the PCM controlled outputs. The PCM monitors throttle position and compares actual throttle position from the TP sensor to a predicted TP value calculated from engine speed. If the PCM detects an excessively low TP sensor signal voltage, DTC P0122 will set.

Conditions for Running the DTC

The ignition is ON.

Conditions for Setting the DTC

•	TP sensor signal voltage is less than 0.1 volt.

•	The above condition is present for more than 10 seconds.

Action Taken When the DTC Sets

•	The PCM will illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the diagnostic test has been run and failed.

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

Conditions for Clearing the MIL/DTC

•	The PCM will turn OFF the malfunction indicator lamp (MIL) during the third consecutive trip in which the diagnostic has 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 a scan tool.

Diagnostic Aids

Inspect for the following conditions:

Many situations may lead to an intermittent condition. Perform each inspection or test as directed.

Important: : Remove any debris from the connector surfaces before servicing a component. Inspect the connector gaskets when diagnosing or replacing a component. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion.

•	Loose terminal connection

-	Use a corresponding mating terminal to test for proper tension. Refer to Testing for Intermittent Conditions and Poor Connections , and to Connector Repairs in Wiring Systems for diagnosis and repair.

Inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and faulty terminal to wire connection. Refer to Testing for Intermittent Conditions and Poor Connections , and to Connector Repairs in Wiring Systems for diagnosis and repair.

•

Damaged harness--Inspect the wiring harness for damage. If the harness inspection does not reveal a problem, observe the display on the scan tool while moving connectors and wiring harnesses related to the sensor. A change in the scan tool display may indicate the location of the fault. Refer to Wiring Repairs in Wiring Systems for diagnosis and repair.

•	Inspect the powertrain control module (PCM) and the engine grounds for clean and secure connections. Refer to Wiring Repairs in Wiring Systems for diagnosis and repair.

If the condition is determined to be intermittent, reviewing the Snapshot or Freeze Frame/Failure Records may be useful in determining when the DTC or condition was identified.

Test Description

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

This vehicle is equipped with a PCM which utilizes an Electrically Erasable Programmable Read Only Memory (EEPROM). When the PCM is being replaced, the new PCM must be programmed.

DTC P0122 - TP Sensor Circuit Low Voltage

Step	Action	Values	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	Important: If DTC P1635 5 Volt Reference Circuit is set, perform that diagnostic first. Install a scan tool. Turn ON the ignition, with the engine OFF. With a scan tool, observe the TP voltage. Does the voltage measure less than the specified value?	0.16 V	Go to Step 4	Go to Step 3
3	Turn ON the ignition, with the engine OFF. Review and record scan tool Failure Records data. Operate the vehicle within Failure Records conditions as noted. Does the DTC reset?	--	Go to Step 4	Go to Diagnostic Aids
4	Turn OFF the ignition. Disconnect the TP sensor harness connector. Connect a 3 amp fused jumper wire between the 5 Volt Reference circuit of the TP sensor and the signal circuit of the TP sensor. Turn ON the ignition, with the engine OFF. With a scan tool, observe the TP voltage parameter. Does the voltage measure at the specified value?	5 V	Go to Step 9	Go to Step 5
5	Disconnect the fused jumper wire. Using a DMM, measure the voltage between the 5 Volt Reference circuit of the TP sensor and the ground circuit of the TP sensor. Does the voltage measure at the specified value?	5 V	Go to Step 7	Go to Step 6
6	Test the 5 Volt Reference circuit of the TP sensor for high resistance or an open and all 5 Volt Reference A circuits and connected components for a short to ground. Refer to Circuit Testing in Wiring Systems. If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition?	--	Go to Step 12	Go to Step 8
7	Test the signal circuit of the TP sensor for a short to ground, a high resistance, or an open. Refer to Circuit Testing in Wiring Systems. If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition?	--	Go to Step 12	Go to Step 8
8	Inspect for poor connections at the harness connector of the PCM. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. If a problem is found, repair as necessary. Refer to Connector Repairs in Wiring Systems. Did you find and correct the condition?	--	Go to Step 12	Go to Step 11
9	Inspect for poor connections at the harness connector of the TP sensor. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. If a problem is found, repair as necessary. Refer to Connector Repairs in Wiring Systems. Did you find and correct the condition?	--	Go to Step 12	Go to Step 10
10	Replace the TP sensor. Refer to Throttle Position Sensor Replacement . Is the action complete?	--	Go to Step 12	--
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 12	--
12	Use a scan tool to clear DTCs. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text. Using a scan tool, monitor Specific DTC info for DTC P0122. Does the scan tool indicate DTC P0122 failed?	--	Go to Step 4	System OK