P0773 indicates an electrical fault in the shift solenoid "E" circuit, which controls hydraulic pressure for a specific gear range. The TCM/PCM detects an open, short, or out‑of‑range signal from the solenoid and stores the code.
The solenoid’s internal coil can develop an open circuit or short to ground, causing the TCM/PCM to detect an electrical fault.
Chafed wires, corroded terminals, or a loose connector can interrupt the signal or create a short, triggering the code.
Less common, but a faulty driver transistor inside the transmission control module can fail to supply proper voltage or ground to the solenoid.
Debris or wear can cause the solenoid to stick mechanically; while primarily a hydraulic issue, it may prevent the solenoid from responding correctly and set an electrical code.
Insufficient fluid pressure or dirty fluid can cause the solenoid to work harder, potentially leading to overheating and intermittent electrical faults.
No. The PCM/TCM is rarely the cause; most P0773 faults are due to the shift solenoid itself, its wiring, or connectors. Replace the module only after those items have been tested and found good.
Low fluid usually causes shift quality issues rather than an electrical fault, but extremely low or dirty fluid can lead to solenoid overheating and intermittent electrical problems, so fluid level should always be checked.
Driving may result in harsh shifts, gear hunting, or the transmission entering limp‑in mode, which can cause further wear. It is advisable to diagnose and repair the fault promptly.
Only if the solenoid is mechanically stuck or the valve body is blocked after electrical checks pass. Most often, the solenoid or its wiring is the culprit, not the entire valve body.