P2791

Code

Generic P — Powertrain

Gate Select Direction Circuit Low

Brand: Generic

Type: P — Powertrain

Views: UK: 37 EN: 28 RU: 31

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Page language: EN

Causes

Damaged or chafed wiring harness to the gate select/shift solenoid
Corroded or loose connector pins at the solenoid or control module
Short to ground in the gate select direction control circuit
Faulty gate select/shift solenoid or valve body component
Low system battery voltage or poor power/ground at transmission control module
Faulty transmission control module (TCM/PCM)

Symptoms

Check Engine/Malfunction Indicator Lamp (MIL) illuminated
Transmission may enter limp or reduced-gear mode
Harsh, delayed, or missing shifts in affected direction
Transmission stuck in one gear or unable to shift into desired gear
Stored/active transmission-related trouble codes

What to check

Read and record stored DTCs and freeze frame data with a scan tool
Inspect battery voltage and engine/vehicle grounds before testing (low voltage can affect circuits)
Visually inspect wiring and connectors at the transmission, valve body, and PCM/TCM for damage, corrosion, or loose pins
Backprobe the gate select direction connector and check for continuity to the control module ground/pin
Check for water intrusion, bent pins, or corrosion at the connector
Attempt to actuate the solenoid/valve using a scan tool and observe response

Signal parameters

Standby (inactive) voltage on control circuit: typically near 0–1 V (may vary by vehicle)
Commanded (active) voltage: typically near battery voltage when driver-type circuit or pulled to ground when sink-type — expect ~10–14 V or switched-to-ground depending on design
Typical solenoid coil resistance: commonly 5–100 ohms depending on design (refer to manufacturer spec)
No continuity or short-to-ground measured between control circuit and vehicle ground when circuit is not commanded

Diagnostic algorithm

Retrieve P2791 and any related codes; note freeze frame and conditions (ignition on, engine running, speed, gear).
Verify battery voltage ≥12.4 V; ensure good engine and chassis grounds before testing. Low voltage can produce false readings.
Visually inspect wiring/connectors at the transmission solenoid/valve body and at the PCM/TCM. Repair damaged insulation, corrosion, or connectors as needed.
With ignition off, disconnect the solenoid connector. Measure solenoid coil resistance and compare to manufacturer spec. If open or out of range, replace solenoid/valve body.
Check continuity between the control module pin and the solenoid connector pin. Look for shorts to ground or open circuits. Repair wiring as needed.
With a backprobe and a digital voltmeter, command the gate select direction solenoid ON and OFF using a scan tool and observe control voltage. Confirm the circuit changes as expected and no short to ground when commanded OFF.
If wiring and solenoid test good but fault persists, swap/connect a known-good solenoid (if available) or perform bench/bench power tests to isolate component vs module.
Repair or replace faulty wiring, connector, or solenoid. If all external wiring and components check good, suspect TCM/PCM and follow manufacturer procedures for module testing/replacement.
Clear codes and perform road test under the same conditions to verify repair. Re-scan after test drive to confirm no return of P2791.

Likely causes

Short to ground in control circuit between PCM/TCM and solenoid
Broken or pinched wire at transmission harness or connector
Faulty/failed gate select direction solenoid or internal valve body failure
Corroded or poorly seated connector at solenoid or module

Fault status

⚠️ Status

Control module detects a persistent low-voltage condition on the gate select direction control circuit (short to ground or open/failed component), stored as P2791. Transmission may enter limp mode until resolved.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.0 hours