P0999 Fault Code

Shift Solenoid F Control Circuit High

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

The P0999 fault code indicates an issue with the Shift Solenoid F Control Circuit High, which is responsible for controlling the operation of the transmission's shift solenoids. This code often signifies that the control circuit for solenoid F has detected a high voltage signal, which can lead to improper shifting and transmission behavior. Here are some details about the fault:

• The solenoid's control circuit might be short-circuited to voltage.
• It can cause erratic transmission shifts or a failure to shift.
• This code is often associated with automatic transmissions in modern vehicles.

What are the symptoms of the P0999 code?

Drivers may experience a range of symptoms if the P0999 fault code is detected:

• Delayed or erratic shifting when accelerating or decelerating.
• Transmission may enter limp mode to prevent damage, limiting the vehicle's speed.
• Unusual noises from the transmission area, such as grinding or clunking sounds.
• Dashboard warning lights may illuminate, including the check engine light.

What causes the P0999 code?

Several factors can lead to a P0999 fault code, including:

• Short circuit within the wiring or connectors related to the solenoid.
• Faulty shift solenoid F that may be stuck in an ON position.
• Poor ground connection in the shift solenoid circuit.
• Issues with the transmission control module (TCM) that may incorrectly interpret the solenoid's position.

How to fix P0999?

To resolve the P0999 fault code, follow these steps:

• Perform a thorough inspection of the wiring and connectors associated with the Shift Solenoid F to check for damage, corrosion, or shorts.
• Test the shift solenoid F for proper operation and replace it if it is faulty.
• Ensure that the ground connections are secure and functioning correctly.
• Clear the fault code from the vehicle’s computer and perform a road test to ensure proper shifting behavior and confirm that the code does not return.