P0923

Code

Generic P — Powertrain

Gear Shift Forward Actuator Circuit High

Brand: Generic

Type: P — Powertrain

Views: UK: 23 EN: 42 RU: 26

AI status

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Page language: EN

Causes

Short to battery (voltage) on the forward actuator circuit
Failed or internally shorted gear shift forward actuator (motor/solenoid)
Poor or corroded connector, pins, or harness damage
Open or high-resistance ground for the actuator
Blown fuse or faulty power relay feeding the actuator circuit
Faulty PCM/TCM or internal driver circuit

Symptoms

Malfunction Indicator Lamp (MIL) illuminated
Transmission may not shift into forward gears or may default to limp/neutral mode
Delayed or harsh engagement when selecting Drive
Stored transmission fault codes along with P0923
Possible inability to move vehicle under own power (depending on vehicle limp strategy)
Unusual clicking or motor noise from actuator area

What to check

Read and record all stored codes and freeze frame data with a scan tool
Visual inspection of actuator connector, wiring harness, and ground straps for damage or corrosion
Check relevant fuses and relays (power to actuator) for correct rating and continuity
Backprobe the actuator connector with a multimeter/oscilloscope to monitor voltage while activating the circuit
Measure resistance of actuator (with ignition off and connector disconnected) and compare to specification
Wiggle test wiring while monitoring circuit to reproduce voltage spikes

Signal parameters

Key ON, engine OFF: control/reference wire typically ~0–0.5 V (inactive) or battery voltage if the circuit is supplied by B+
Activated command: PWM or switched voltage up to battery voltage (~9–14 V) depending on system design
Actuator coil resistance (typical range): 2–50 ohms (vehicle-specific — check service manual)
High-voltage fault condition is set when measured voltage exceeds the expected maximum for the circuit or the PCM sees continuous B+ on a low-side driver

Diagnostic algorithm

Use a scan tool to confirm P0923 and note any additional transmission codes and freeze frame data. Clear codes and attempt to re-create.
Perform a thorough visual inspection of wiring, connectors, and ground near the transmission and actuator. Repair obvious damage.
Verify fuses/relays in the actuator power feed are intact and correct. Replace if faulty.
With ignition ON (engine OFF), backprobe the actuator connector: measure voltage on the power lead and control/driver lead. Look for constant B+ where it should be low or pulsed.
Disconnect connector and measure actuator coil resistance to ground and between terminals. Compare to spec. An abnormally low resistance may indicate an internal short.
If wiring appears suspect, perform continuity tests to battery positive and to chassis ground. Check for short to B+ (unexpected battery voltage on control wire with connector disconnected).
If wiring checks pass, bench-test or temporarily apply fused 12V to the actuator (follow vehicle-specific safe procedures) to confirm mechanical/electrical operation.
Repair or replace damaged wiring, connector terminals, grounds, fuses, or the actuator as required. If harness repairs are made, secure and protect wiring from chafing.
If the actuator and wiring are good but fault persists, consider PCM/TCM driver failure. Verify updated software and perform module diagnostics; replace module only after all wiring and actuator tests confirm correct operation.
Clear codes and road test to verify repair. Re-scan for stored codes.

Likely causes

Pinched/chewed wiring contacting constant B+
Corroded or pushed-out terminal at the actuator connector
Actuator motor shorting to its supply internally
Missing or loose ground strap at the transmission
Blown or improperly rated fuse replaced incorrectly

Fault status

⚠️ Status

Detected high voltage on Gear Shift Forward Actuator circuit. The transmission control module has flagged an over-voltage condition on the forward shift actuator wiring or driver (P0923).

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-3.0 hours