DTC P0122 Throttle Position (TP) Sensor Circuit Low Voltage. Buick GL7 (Export) 2000

For 1990-2009 cars

### Circuit Description

The throttle position (TP) sensor circuit provides a voltage signal that changes relative to the throttle blade angle. The signal voltage will vary from less than 1.0 volt at closed throttle to more than 4.0 volts at wide open throttle (WOT). The PCM monitors the throttle position and compares the actual throttle position from the TP sensor to a predicted TP value calculated from the engine speed. If the powertrain control module (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

• | The TP sensor signal voltage is less than 0.1 volt.

• | The above conditions are present for more than 10 seconds.

### 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 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 the MIL OFF 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 with the scan tool.

### Diagnostic Aids

Inspect for the following conditions:

• | A poor connection at the PCM or the TP sensor. Inspect the harness connectors for the following conditions:

• | Backed-out terminals

• | Improper mating

• | Broken locks

• | Improperly formed or damaged terminals

• | Poor terminal-to-wire connection

• | Use a corresponding mating terminal to test for the proper terminal tension.

• | A 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 the connectors and the wiring harnesses related to the sensor. A change in the display will indicate the location of the fault. Refer to Wiring Repairs in Wiring Systems.

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

### Test Description

The number below refers to the step number on the diagnostic table.

1. This vehicle is equipped with a PCM which utilizes an electrically erasable programmable read-only memory (EEPROM). If the PCM is 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: Go to DTC P1635 if it sets while the engine is running.

1. Install a scan tool.
2. Turn ON the ignition, leaving the engine OFF.
3. With a scan tool, observe the TP voltage parameter in the PCM data list.

Is the TP sensor voltage less than the specified value?

0.16 V

Go to Step 4

Go to Step 3

3

1. Turn ON the ignition switch.
2. Review and record the scan tool Failure Records data.
3. Operate the vehicle within the Failure Records conditions as noted.
4. Using a scan tool, monitor the Specific DTC info for DTC P0122.

Does the scan tool indicate DTC P0122 failed?

--

Go to Step 4

Go to Diagnostic Aids

4

1. Turn OFF the ignition.
2. 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.
3. Turn ON the ignition, leaving the engine OFF.
4. With a scan tool, observe the TP voltage parameter.

Does the TP sensor voltage equal the specified value?

5 V

Go to Step 9

Go to Step 5

5

1. Disconnect the fused jumper wire.
2. Using a digital multimeter (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 equal 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. Test all the 5 volt reference A circuits and the connected components for a short to ground. Refer to Circuit Testing and 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 and 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 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 Testing for Intermittent Conditions and Poor Connections 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. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Did you complete the replacement? | -- | Go to Step 12 | --

12

1. Review and record the scan tool Failure Records data.
2. Clear the DTCs.
3. Operate the vehicle within the Failure Records conditions as noted.
4. Using a scan tool, monitor the Specific DTC info for DTC P0122.

Does the scan tool indicate DTC P0122 failed?

--

Go to Step 4

System OK