What does it mean?
The throttle position sensor (TPS) is located on the throttle body. It is a type of variable resistor which changes its resistance value according to throttle position. As the throttle is opened, the voltage reading goes up. This information is used by the PCM to determine output controls such as fuel injection and idle air control. Most throttle position sensors are simple and easy to troubleshoot. There are three wires attached to the TPS: power, ground and signal.
Power, or reference voltage, goes into the TPS. The sensor then sends a return signal voltage to the PCM. The return voltage depends on throttle positon. Typically, the signal value at idle will be about .45 volts. This voltage reading increases as the throttle is opened and will read about 4.5 volts at wide open throttle (WOT). Many late model vehicles don’t use a throttle wire. Instead, they use what is referred to as “drive by wire”.
In these systems, a motor is used to operate the throttle using inputs from position sensors on the accelerator pedal. When the gas pedal is depressed, the control module commands the throttle to open. Then, a pair of TPS sensors relay the throttle positon to the control module so it knows everything is working properly. A typical throttle position sensor Note: “Circuit Malfunction” indicates that there is a malfunction in the control circuit, as opposed to a fault in a sensor or other component.
With “Circuit Malfunction” codes, replacement of sensors and components in the affected circuit will almost never resolve the problem, since as the code suggests, the trouble is in the circuit. This distinction between “circuit” and “sensor/component” is a great help to anyone trying to diagnose a circuit malfunction code, since it narrows the list of possible causes down considerably.
The causes of “Circuit Malfunction” codes are much the same as those for “Open Circuits” i.e., broken wiring, poor connections across electrical connectors or previously repaired wiring, loss of ground that prevents current flow, blown fuses, defective relays, faulty switches, or any of a host of other issues and problems that prevents a flow of current through wiring. Issues like high/low/intermittent voltages can set a “Circuit Malfunction” code on some applications.
Moreover, “Circuit Malfunction” codes could also indicate a problem with negative current control / flow, as well as issues with failed or failing PCM’s (Powertrain Control Modules), although control module failure is a rare event.