Circuit Description
The Throttle Position (TP) sensor provides a voltage signal that changes relative to the throttle blade angle. The signal voltage varies from about 0.5 volt at idle to about 5.0 volts at wide open throttle.
The TP sensor signal is one of the most important inputs used by the ECM for fuel control and for most of the ECM control outputs.
Conditions for Setting the DTC
| • | Engine idling |
| • | TP sensor signal voltage greater than about 2.5 volts |
| • | All conditions met for 8 seconds |
Or
The TP sensor signal voltage over 4.5 volts with the ignition ON
Action Taken When the DTC Sets
The Malfunction Indicator Lamp (MIL) will illuminate. The system will go Open Loop.
Conditions for Clearing the MIL/DTC
The conditions for the fault are no longer present and 50 ignition cycles have passed with no further faults or the ignition switch is turned OFF and the battery feed voltage is removed for 10 seconds.
Diagnostic Aids
A scan tool reads the throttle position in volts. The scan tool should read about 0.45 to 1.25 volts with throttle closed and the ignition ON or at idle. The voltage should increase at a steady rate as the throttle moves toward WOT.
Also some scan tools will read the throttle angle. 0 percent = closed throttle: 100 percent = WOT.
Refer to Intermittent Conditions .
Scan TP sensor while depressing the accelerator pedal with engine stopped and the ignition ON. The display should vary from below 1.25 volts when throttle was closed, to over 4.5 volts when throttle is held at wide open throttle position.
Test Description
The numbers below refer to the step numbers on the Diagnostic Table.
-
With the throttle closed, the TP sensor should read less than 1.25 volts. If it does not, replace the TP sensor.
-
With the TP sensor disconnected, the TP sensor voltage should go low if the ECM and wiring are OK.
-
Probing the sensor ground with a test lamp checks the 5 volts return circuit because a faulty 5 volts return will cause a DTC 21.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the On-Board Diagnostic (OBD) System Check? | -- | ||
Does the scan tool display the Throttle Position signal voltage over the specified value? | 1.25 V | Go to Diagnostic Aids | ||
Disconnect the Throttle Position (TP) sensor. Does the scan tool display the Throttle Position signal voltage less than the specified value? | 0.2 V (200 mV) | |||
4 |
Did you find a problem? | -- | ||
Probe the Throttle Position sensor ground circuit with a test lamp connected to B+. Is the test lamp ON? | -- | |||
6 |
Did you find a problem? | -- | ||
7 | Replace the Throttle Position (TP) sensor. Refer to Throttle Position Sensor Replacement . Is the action complete? | -- | -- | |
8 |
Did you find a problem? | -- | ||
9 | Replace the ECM. Refer to Engine Control Module Replacement . Is the action complete? | -- | -- | |
10 |
Did the DTC reset? | -- | ||
11 | Are any DTCs stored which you have not diagnosed? | -- | Go to the Applicable DTC Table | System OK |
