1994 Toyota Camry Transmission Failure: P0500 & P0720 Codes - Reverse Works, No Forward Gears
I'm experiencing serious transmission issues with my 1994 Toyota Camry. The vehicle will engage reverse gear (though not smoothly) but fails to shift into any forward gears. Diagnostic trouble codes P0500 and P0720 are present. These codes typically point to a malfunctioning Vehicle Speed Sensor (VSS) or its wiring circuit. However, I'm unsure whether the VSS failure is causing the transmission issue or if a damaged transmission itself is leading to the sensor reading errors. Specifically: Does a failing VSS prevent forward gear operation? Or does a worn-out transmission cause the VSS to misread and generate these codes? The car has 116,000 miles and has always been well-maintained, with only three months of inactivity before symptoms appeared.
On Chrysler and some Ford models, if the speed signal or range switch fails, shifting will not occur. However, if transmission slippage is severe, it can trigger a rear speed sensor code because the system detects insufficient output speed. If wiring to the VSS is intact, try replacing the sensor first. But if transmission fluid appears discolored, it's best to have a professional inspect the transmission.