P28D1: Clutch A Motor Driver Current/Temperature Too High

What it means

The output driver for the clutch A BLDC motor reports current or junction temperature above its protection threshold. Sustained high load or short-circuit fault.

At a glance

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

How it works

The clutch A motor driver is the electronic output stage that supplies current to the clutch A brushless motor, and it monitors current and its own junction temperature for protection. P28D1 sets when current or driver temperature exceeds its protection threshold, which may happen if the motor stalls or its phases short together.

Common causes

Most likely first.

1. Motor stalled - high stall current
2. Short between motor phases

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. Save freeze-frame data and review transmission live data for clutch A motor current, temperature, and commanded movement around the time of the fault.
2. Inspect the clutch A actuator and coupling for a jam or binding that could stall the motor.
3. With power off and following the manufacturer's safety procedure, inspect the motor phase wiring and connectors for damage, shorting, or corrosion.
4. Test the clutch A motor phase circuits for shorts between phases or to ground using the manufacturer's procedure.
5. If the motor and wiring pass checks, diagnose the driver output stage for a current or temperature fault according to the manufacturer.

Common fixes

• Free or repair a binding clutch A actuator mechanism that is stalling the motor.
• Repair damaged clutch A motor phase wiring or connector terminals.
• Replace the clutch A motor if testing confirms a phase short or internal fault.
• Repair or replace the motor driver module if the motor and wiring are sound but the driver still reports overcurrent or overheating.

Can I keep driving?

Avoid continued driving if the transmission shifts poorly or enters limp mode, since the clutch A motor may stop operating and prevent reliable gear changes. Stop if drive is lost or the transmission overheats.