P278D Fault Code

Kick Down Switch Circuit High

• What does that mean?
• Symptoms
• Causes
• Solutions

The P278D fault code indicates an issue with the Kick Down Switch Circuit, which is responsible for signaling the transmission control module (TCM) when the accelerator pedal is fully pressed. This allows the vehicle to downshift for maximum power and acceleration. A high signal from this circuit can suggest an electrical issue or a malfunction within the switch itself.

What are the symptoms of the P278D code?

Common symptoms associated with the P278D fault code are:

• Delayed or harsh shifting of the transmission.
• Poor acceleration when pressing the accelerator pedal.
• In some cases, the vehicle may go into limp mode, reducing power to prevent further damage.
• Trouble with automatic gear shifting, particularly when trying to accelerate quickly.

What causes the P278D code?

The primary causes of a P278D code include:

• A faulty kick down switch that remains closed or sends a high signal unexpectedly.
• Damaged wiring or connectors in the kick down switch circuit.
• Short circuits in the electrical components related to the transmission control.
• Issues with the transmission control module (TCM) software or configuration.

How to fix P278D?

To resolve the P278D code, consider the following steps:

• Inspect and test the kick down switch for proper function and replace if faulty.
• Check the wiring and connectors for damage or corrosion and repair or replace as necessary.
• Reset the TCM and clear the fault code, then test drive to see if the issue reoccurs.
• If problems persist, a thorough diagnostic may be required on the TCM and its programming.