P27F5: Gear Shift Lock Solenoid/Actuator A Stuck Off

What it means

The shift lock solenoid for selector lever A does not engage when commanded. The selector can be moved without the safety interlock active.

At a glance

• Usually lights the check-engine light

How it works

Shift lock actuator A engages the selector interlock to prevent movement when the required release conditions are absent. P27F5 indicates the actuator did not engage when commanded, leaving the selector able to move without that safety lock.

Common causes

Most likely first.

1. Lock actuator failed mechanically
2. Open in solenoid control wire
3. Carbon or debris buildup preventing free movement

Symptoms

• Shift lever may move without the shift-lock interlock engaging
• Shift interlock or transmission warning light may come on

How to diagnose it

1. With the vehicle safely parked, check whether the selector moves when the interlock should hold it and note whether the brake is applied.
2. Scan the relevant module for shift-lock commands and related brake-switch or interlock codes.
3. Inspect actuator A and the selector mechanism for debris, binding, damage, or a connector that is not fully seated.
4. Check actuator A’s control wire and connector for an open circuit or corrosion.
5. Measure for the commanded actuator signal at actuator A and check continuity as directed by the manufacturer’s specification.

Common fixes

• Remove debris preventing actuator A from moving freely.
• Repair an open or damaged actuator A control wire or connector.
• Replace actuator A if it fails to engage despite a correct command and circuit.
• Repair the control circuit only after testing identifies a module or driver fault.

Can I keep driving?

Do not rely on the shift lock to prevent unintended selector movement; keep the parking brake applied and the vehicle secured when parked. Have the interlock repaired promptly, especially if the lever can move unexpectedly.