P28E7: Shift Motor Position Sensor Circuit/Open

What it means

The TCM cannot read a valid signal from the shift motor rotor position sensor. Open wiring or sensor failure.

At a glance

• Usually lights the check-engine light
• The engine or gearbox may go into limp mode

How it works

The shift motor moves the transmission mechanism between gear positions, and its rotor position sensor reports where the motor is. The TCM sets P28E7 when it cannot read a valid sensor signal because the circuit is open, such as a broken signal wire or a poor connection at the sensor.

Common causes

Most likely first.

1. Open in sensor signal wire
2. Position sensor failed
3. Pin pushed back out of connector body

Symptoms

• Check engine or transmission warning light on
• Harsh, delayed, or missing shifts
• Possible limp mode (locked in one gear)
• Slipping or shuddering during gear changes

How to diagnose it

1. Check the freeze-frame and transmission data for when the fault occurred, and note whether the shift motor position reading is missing or drops out.
2. With the ignition off, inspect the shift motor position sensor connector for a pushed-back pin, looseness, corrosion, or damaged wiring.
3. Check continuity of the sensor signal wire between the sensor and TCM, following the wiring diagram; an open circuit points to a break or poor terminal contact.
4. Check the sensor supply and ground circuits against the manufacturer's specification to confirm the sensor has the inputs needed to produce a signal.
5. If wiring and connector tests pass, test the position sensor and its signal at the sensor and TCM while the shift motor is commanded to move, then compare readings with the manufacturer's specification.

Common fixes

• Reseat the connector and repair a pushed-back or loose terminal.
• Repair an open or damaged sensor signal wire.
• Clean or replace corroded connector terminals and restore a secure connection.
• Replace the shift motor position sensor if its output fails the manufacturer's tests.

Can I keep driving?

Avoid driving if shifts are missing, slipping, or the transmission is in limp mode; an unreliable shift position signal can leave the vehicle in an unsuitable gear. If shifting remains normal, limit driving and arrange prompt diagnosis, since the fault can worsen into loss of gear selection.