Wednesday, March 6, 2013
How To Repair Your Throttle Body for less than $2 dollars P0120 DTC - TPS A Circuit Malfunction OBD-II Trouble Code Technical Description Throttle Position Sensor/Switch (TPS) A Circuit Malfunction What does that mean? The TPS (Throttle Position Sensor) is a potentiometer that is mounted to the throttle body. It detects the throttle blade angle. As the throttle blade moves, the TPS sends a signal to the PCM (Powertrain Control Module). Usually a three wire sensor: A 5 volt reference from the PCM to the TPS, a ground from the PCM to the TPS, and a signal return from the TPS to the PCM. The TPS sends the throttle position information back to the PCM on this signal wire. When the throttle is closed the signal is near .45 volts. At WOT (Wide Open Throttle) the TPS signal voltage will approach a full 5 volts. When the PCM sees a voltage that is outside of normal operating range, P0120 will set. NOTE: The PCM knows that any large change in throttle position means a cooresponding change in manifold pressure (MAP). On some models the PCM will monitor MAP and TPS operation for comparison. Meaning that if the PCM sees a large percentage change in throttle position, it expects to see a cooresponding change in manifold pressure and vice versa. If it doesn't see this comparitive change, P0120 may set. This doesn't apply to all models. Symptoms Potential symptoms include: MIL (Malfunction Indicator Lamp) illumination Misfiring at idle or at highway speed Poor idle quality Possibly won ...
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