دائرة مفتوحة في أسلاك سرعة المحرك

A break in the wiring carrying the engine speed signal to the transmission module. Some transmissions receive engine speed as a hard-wired signal rather than over the network, which is a deliberate choice — the shift calculation needs it quickly and reliably — and it means there is a physical circuit to break.

Losing it prevents the module verifying slip. It compares engine speed against input speed to know whether the torque converter or a clutch is slipping, so without it the ratio checks cannot run and the module reports the input circuit while defaulting to a conservative strategy.

The wire runs between the engine and the transmission, which is the worst place for it: heat, vibration and relative movement between two components on flexible mounts. Check where the harness crosses that gap and where it passes any bracket, and inspect the case connector, which is a frequent failure point. Worn engine mounts make it likelier, because they increase the movement the harness has to absorb — so a broken wire there is worth treating as a symptom as well as a fault.