The clutch is what securely locks the engine and transmission to each other. Most newer vehicles have a transmission control module which electronically activates and deactivates the clutch. The module operates something called a clutch actuator to control the clutch in this way.
First, you have the electric motor which causes the clutch master cylinder to move. On the clutch actuator, you have the clutch stroke sensor attached to it. This is what detects the position of the clutch master cylinder. This information is sent back to the powertrain control module, where the electrical current from the clutch motor is monitored.
The powertrain control module is always checking on the output voltage coming from the clutch actuator. This occurs whenever the actuator disengages or engages the clutch. For the clutch to be released, the powertrain control module must transmit a signal to the actuator. Then the module can change gears accordingly.
The transmission control module stays in communication with the powertrain control module. If the clutch fails to function properly because the clutch actuator has a problem with its control circuit, then it’ll cause the Check Engine warning light to turn on. Once you run a diagnostic scan to discover the problem, you’ll likely receive trouble code P0900 on the display screen of the scanner. This indicates you have an open circuit in your clutch actuator.
Now, what does this mean? It means you may have one or more problems with some of the corresponding components here. You may have damaged wires, corrosion on the electrical connector, bad motion sensors, bad travel sensors, or electrical malfunctions within the actuator. Only a certified mechanic can discover the true cause of the problem. They’ll inspect your clutch actuator assembly, clutch actuator circuit, and powertrain control module voltage and overall condition.
You’ll know when a problem exists because the symptoms of trouble code P0900 will be intolerable. Some of the symptoms include engine stalling, engine failing to crank, transmission cannot change gears, or transmission activates “limp mode.” How long do you think you can drive with these symptoms present? Not very long, that’s for sure.