DTC P0122 Throttle Position (TP) Sensor Circuit Low Voltage. Buick Riviera 1999

For 1990-2009 cars only

Makes 🢒 Buick 🢒 1999 🢒 Riviera 🢒 DTC 🢒 DTC P0122 Throttle Position (TP) Sensor Circuit Low Voltage

Engine Controls Components
Engine Controls Schematics
OBD II Symbol Description 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 below 1.0 volt at closed throttle to above 4.0 volts at Wide Open Throttle (WOT). 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 Running the DTC

The engine is running.

Conditions for Setting the DTC

•	TP sensor signal voltage is less than 0.1 volt.

•	Above conditions are present for longer than 1 second.

Action Taken When the DTC Sets

•	The PCM illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.

•

The PCM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the PCM stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the PCM records the operating conditions at the time of the failure.

•	The PCM writes the conditions to the Freeze Frame and updates the Failure Records.

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

Check for the following conditions:

•	Poor connection at PCM and TP Sensor.

Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection. Use a corresponding mating terminal to test for proper tension.

•	Damaged harness.

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

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 Throttle Position (TP) Sensor Circuit Intermittent Low Voltage Diagnostic Chart may isolate the cause of the malfunction.

Test Description

Number(s) below refer to the step number(s) 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	Value(s)	Yes	No
1	Did you perform the OBD Diagnostic System Check?	--	Go to Step 2	Go to Powertrain On Board Diagnostic (OBD) System Check
2	Install a scan tool. Turn ON the ignition, with the engine OFF. With a scan tool, observe the TP voltage parameter in the PCM data list. Does the scan tool indicate that the TP voltage parameter is less than the specified value?	0.16V	Go to Step 4	Go to Step 3
3	Turn ON the ignition switch. Review and record scan tool Fail Records data. Operate the vehicle within Fail Records conditions as noted. 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	Turn OFF the ignition. 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 scan tool indicate that the TP voltage parameter is equal to the specified value?	5V	Go to Step 9	Go to Step 5
5	Disconnect the fused jumper wire. Using a J 39200 , 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 equal to the specified value?	5V	Go to Step 7	Go to Step 6
6	Test the 5 volt reference circuit of the TP sensor for high resistance for an open and all 5 volt reference A circuits and connected components for a short to ground. 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 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 Intermittents and Poor Connections Diagnosis and 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 Intermittents and Poor Connections Diagnosis and 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 Did you complete the replacement?	--	Go to Step 12	--
11	Important: The replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming . Replace the PCM. Did you complete the replacement?	--	Go to Step 12	--
12	Review and record scan tool Fail Records data. Clear DTCs Operate the vehicle within Fail Records conditions as noted. 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