What does it mean?
The throttle body or linkage of some vehicles may contain a switch that indicates to the Powertrain Control Module (PCM) or Engine Control Module (ECM) when the throttle body is in the closed position. When the throttle body is closed, the switch will be pressed or in the closed position. The PCM uses this switch to keep the engine idling in conjunction with the idle air control valve and/or to enter fuel cut-off mode during coasting.
There may also be a Wide Open Throttle (WOT) switch. If the WOT or closed throttle switch is not engaged, the PCM or ECM may assume that the throttle is partially open, which could affect the air/fuel ratio.
Note: If multiple fault codes are present, such as P0120 (TPS/Pedal Position Sensor A Circuit Malfunction) – there may be an open in the ground circuit or a poor connection to the Throttle Position Sensor TPS).
Symptoms
Symptoms of a DTC P0510 include the illumination of the Malfunction Indicator Lamp (MIL); you will likely not notice any other symptoms.
Causes
Potential causes of a P0510 code include:
- Open circuit in the wiring harness or loose/dirty connection
- Faulty closed throttle position switch
- Altered throttle body idle adjustment screw
- Faulty ECM
Possible Solutions
Wiring Harness – Disconnect the wiring harness connector at the Throttle Position Sensor (TPS) or closed throttle position switch and the wiring harness connector at the PCM/ECM. Using a digital voltmeter (DVOM) set to the ohms scale, connect the leads to each end of the same wire using a wiring diagram for reference to test continuity between the switch and the PCM/ECM. Resistance should be present in the wiring between the switch and the PCM/ECM; an infinite reading would indicate an open circuit. Repair the open wiring or replace the wiring harness.
Closed Throttle Position Switch – Disconnect the wiring harness connector at the TPS or closed throttle position switch and test continuity using the DVOM with the leads on the two pins of the closed throttle position switch or throttle position sensor, depending on the vehicle. Resistance should be present when the throttle body is in the closed position. If the throttle body linkage does not touch or fully close the switch, an idle adjustment screw setting may have been performed. Readjust the idle adjustment screw to specifications using the factory procedure.