P28D6: Clutch B Motor Driver Current/Temperature Too High

What it means

The output driver for the clutch B 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

A power driver controls current to the clutch B brushless motor, and the transmission control module monitors that driver's current and temperature protection status. This code sets when the driver reports excessive current or overheating, which can result from a stalled motor or a short between motor phases.

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. Capture freeze-frame data and check whether the code occurred during a clutch B motor command, along with any supply-voltage or driver-temperature data available.
2. Inspect the clutch B motor and its U, V and W wiring for pinched insulation, melted areas, fluid intrusion or phase wires touching each other.
3. Check the motor and controller connectors for loose or corroded terminals that could cause abnormal current or heating.
4. With power isolated according to the manufacturer's procedure, test for shorts between the phase wires and measure winding paths against the manufacturer's specification.
5. If the wiring and motor pass, use the manufacturer's diagnostic procedure to evaluate whether the clutch B motor is binding or the output driver itself is overheating.

Common fixes

• Repair damaged phase-wire insulation where conductors are shorting together.
• Clean or repair poor connections at the clutch B motor or controller.
• Replace the clutch B motor if it is stalled, binding internally or has a shorted winding.
• Repair or replace the motor output driver only after wiring and motor checks identify it as the cause.

Can I keep driving?

Avoid driving if the transmission slips, shudders or enters limp mode; repeated high current or overheating can disable clutch B control and worsen damage to the motor driver. If shifting is currently normal, keep use minimal and stop if a transmission warning or worsening shift symptoms appear.