GM Service Manual Online
For 1990-2009 cars only

Object Number: 614830  Size: SF
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 1 volt at Closed Throttle to 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. If the PCM detects a TP signal voltage that is intermittently less than the range of the TP sensor, DTC P1122 will set.

Conditions for Running the DTC

The ignition is ON.

Conditions for Setting the DTC

The TP sensor intermittently indicates a throttle position signal less than 0.1 volt.

Action Taken When the DTC Sets

The PCM stores conditions which were present when the DTC set as Failure Records only. This information will not be stored as Freeze Frame Records.

Conditions for Clearing the MIL/DTC

    • The DTC becomes history when the conditions for setting the DTC are no longer present.
    • The history DTC clears after 40 malfunction free warm-up cycles.
    • The PCM receives a clear code command from the 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.

DTC P1122 - TP Sensor Circuit Intermittent 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.

Is DTC P0122 set?

--

Go to DTC P0122 Throttle Position (TP) Sensor Circuit Low Voltage

Go to Step 3

3

Test all 5 Volt Reference A circuits and connected components for an intermittent short to ground. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 8

Go to Step 4

4

Test the 5 Volt Reference circuit of the TP sensor for an intermittent open. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 8

Go to Step 5

5

Test the signal circuit of the TP sensor for an intermittent short to ground, high resistance, or open. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 8

Go to Step 6

6

  1. Inspect for poor connections at the harness connector of the TP sensor. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
  2. 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 8

Go to Step 7

7

  1. Inspect for poor connections at the harness connector of the PCM. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
  2. 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 8

Go to Diagnostic Aids

8

  1. Use a scan tool to clear DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

--

Go to Step 2

System OK