What's the reason for no response when shifting to R gear in an automatic transmission car?
2 Answers
There are many reasons why the R gear may not respond when reversing an automatic transmission car. For example, if components such as the transmission, oil pump, torque converter, control circuits, solenoid valves, or switches malfunction, the reverse gear may fail. Operational reasons: If the electronic parking brake is not released or the gear shifting is not properly engaged, the reverse gear may also become ineffective. In most cases, the inability to reverse in an automatic transmission car can be attributed to transmission issues. First, check if the transmission has insufficient oil, whether the main oil pressure and gear oil pressure are normal, then verify if the gear switch signal is normal, if the wiring from the transmission computer to the shift solenoid valve is intact, and if the gear solenoid valve is functioning properly. If all these are fine, it indicates a problem with the internal control system of the transmission, requiring disassembly to inspect the internal components.
I encountered the same issue last month when my car wouldn't move in reverse gear in the parking lot, as if it had stalled. After careful consideration, these might be the possible causes: the transmission gear lock solenoid valve might be stuck (this component controls the gear shifting action); or the shift cable could be loose or broken (my neighbor's car had this exact problem); another possibility is a faulty brake light switch, since most automatic transmissions nowadays require pressing the brake pedal to engage reverse gear. Also, don't overlook the transmission fluid - if it hasn't been changed for too long and becomes viscous, it can affect the hydraulic system. At that time, I tried restarting the engine multiple times, but eventually had to call a tow truck to the repair shop. The diagnosis revealed a faulty gear position sensor, and replacing this small component fixed the problem.
