DTC P0122 Throttle Position (TP) Sensor Circuit Low Voltage. Pontiac Bonneville 1998

For 1990-2009 cars only

Makes 🢒 Pontiac 🢒 1998 🢒 Bonneville 🢒 Engine 🢒 Engine Controls - 3.8L 🢒 DTC P0122 Throttle Position (TP) Sensor Circuit Low Voltage

Engine Controls Components
Cell 20: Sensors
OBD II Symbol Description 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 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 be set.

Conditions for Setting the DTC

•	The engine is running.

•	TP sensor signal voltage is less than 0.16 volt.

•	The above conditions are present for at least 1 second.

Action Taken When the DTC Sets

•	The PCM will illuminate the malfunction indicator lamp (MIL) during the first 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 and Failure Records data.

Conditions for Clearing the MIL/DTC

•	The PCM will turn OFF the MIL during 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.

Diagnostic Aids

Check for the following conditions:

•	Poor connection at PCM.

Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection

•	Damaged harness.

Inspect the wiring harness for damage. If the harness appears to be OK, observe the throttle position display on the scan tool while moving connectors and wiring harnesses related to the TP sensor. A change in the display will indicate the location of the malfunction.

If DTC P0122 cannot be duplicated, the information included in the Fail Records data can be useful in determining vehicle mileage since the DTC was last set. If it is determined that the DTC occurs intermittently, performing the DTC P1122 Diagnostic Chart may isolate the cause of the malfunction.

Test Description

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. Refer to PCM Replacement and Programming Procedures in Powertrain Control Module (PCM) and Sensors.

DTC P0122 - TP Sensor Circuit Low Voltage

Step	Action	Values	Yes	No
1	Was the Powertrain On-Board Diagnostic (OBD) System Check performed?	--	Go to Step 2	Go to Powertrain On Board Diagnostic (OBD) System Check
2	Turn ON the ignition switch, engine not running. With the throttle closed, observe the TP Sensor voltage display on the scan tool. Is TP Sensor voltage less than the specified value?	0.16V	Go to Step 4	Go to Step 3
3	Review and record scan tool Fail Records data. Operate the vehicle within Fail Records conditions. Using a scan tool, monitor Specific DTC info for DTC P0122. Does the scan tool indicate DTC P0122 failed?	--	Go to Step 4	Go to Diagnostic Aids
4	Disconnect the TP sensor electrical connector. Jumper the 5 volt reference A circuit and the TP signal together at the TP sensor harness connector. Observe the TP Sensor display on the scan tool. Is TP Sensor at the specified value?	5V	Go to Step 11	Go to Step 5
5	Connect a test lamp between B+ and the TP sensor signal circuit at the TP sensor harness connector Observe the TP Sensor display on the scan tool. Is TP Sensor at the specified value?	5V	Go to Step 6	Go to Step 8
6	Turn OFF the ignition switch. Disconnect the PCM. Check the 5 volt reference A circuit for an open or short to ground, or short in other sensors. If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems. Was a problem found?	--	Go to Step 14	Go to Step 7
7	Check the 5 volt reference A circuit for a poor connection at the PCM. If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems. Was a problem found?	--	Go to Step 14	Go to Step 13
8	Turn OFF the ignition switch. Disconnect the PCM. Check the 5 volt reference A circuit for a short to ground or for a short to the TP sensor ground circuit. If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems. Was a problem found?	--	Go to Step 14	Go to Step 9
9	Check the TP signal circuit for an open, short to ground, or short to the sensor ground circuit. If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems. Was a problem found?	--	Go to Step 14	Go to Step 10
10	Check the TP sensor signal circuit for a poor terminal connection at the PCM. If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems. Was a problem found?	--	Go to Step 14	Go to Step 13
11	Check the TP sensor signal circuit for a poor connection at the TP sensor. If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems. Was a problem found?	--	Go to Step 14	Go to Step 12
12	Replace the TP sensor. Refer to Throttle Position Sensor Replacement . Is action complete?	--	Go to Step 14	--
13	Important: The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Is action complete?	--	Go to Step 14	--
14	Review and record scan tool Fail Records data. Clear DTCs Operate the vehicle within Fail Records conditions. 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