Technical Description of OBD-II Trouble Code
Malfunction in the Closed Throttle Position Switch
This diagnostic trouble code (DTC) is a generic OBD-II powertrain code. It is considered generic because it applies to all makes and models of vehicles (1996-newer), although specific repair steps may vary depending on the model.
What does that mean?
On certain vehicles, the throttle body or linkage may have a switch that informs the Powertrain Control Module (PCM) or Engine Control Module (ECM) when the throttle body is closed. When the throttle body is closed, the switch will be depressed or in the closed position. The PCM uses this switch in conjunction with the idle air control valve and/or fuel cut mode to keep the engine at idle or while coasting.
There may also be a Wide Open Throttle (WOT) switch. If either 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 more than one trouble code is present, such as P0120 (TPS/Pedal Position Sensor A circuit Malfunction) – there may be an open in the ground circuit or a bad connection at the Throttle Position Sensor (TPS).
Symptoms
Symptoms of a P0510 DTC will include the illumination of the Malfunction Indicator Lamp (MIL), and you will likely not notice any other symptoms.
Causes
Potential causes of a P0510 code include:
Possible Solutions
Wiring Harness – Disconnect the wiring harness connector at the Throttle Position Sensor (TPS) or closed throttle position switch and the harness connector at the PCM/ECM. Using a Digital Volt Ohm Meter (DVOM) set to the ohms scale, connect the leads to each end of the same wire using a wiring diagram for reference to test for continuity between the switch and the PCM/ECM. There should be resistance in the wiring between the switch and PCM/ECM. An infinite reading would indicate an open circuit. Repair any open in the wiring or replace the wire harness assembly.
Closed Throttle Position Switch – Disconnect the wiring harness connector at the TPS or closed throttle position switch and test for continuity using the DVOM with the leads on the two pins at the closed throttle position switch or the throttle position sensor, depending on the vehicle. There should be resistance when the throttle body is in the closed position. If the throttle body linkage is not touching or fully closing the switch, there may have been an adjustment made to the idle set screw. Re-adjust the idle set screw to specifications using the factory procedure.
