Fix P099C: STEP-BY-STEP diagnostic GUIDE!

The P099C: Shift Solenoid ‘G’ Control Circuit High refers to a high voltage issue in the control circuit of shift solenoid ‘G’. This can be caused by a faulty solenoid, excessive voltage supply, or wiring/connector issues, which can affect the transmission’s shifting performance.

P099C – Quick Overview

Code	Information
Meaning	P099C: Shift Solenoid ‘G’ Control Circuit High
Is it serious?	Yes, this issue can cause erratic shifting or transmission malfunction.
Possible causes	– High voltage in the shift solenoid ‘G’ control circuit – Faulty shift solenoid ‘G’ – Wiring or connector issues
How to diagnose?	– Check the circuit for high voltage – Inspect wiring and connectors – Replace the shift solenoid ‘G’ if necessary

P099C Meaning

The P099C code indicates that the shift solenoid ‘G’ is receiving a higher voltage than expected. This can lead to transmission shifting issues or other performance problems. The issue may arise due to faulty wiring, connectors, or a malfunctioning solenoid.

Step-by-step diagnostic guide

Action	Description	Tools Needed
Check for Other Codes	Use an OBD-II scanner to check for additional transmission-related codes.	OBD-II Scanner
Inspect Shift Solenoid ‘G’	Visually inspect the shift solenoid ‘G’ for any visible damage or malfunction.	Flashlight, Safety Gloves
Test the Circuit for High Voltage	Use a multimeter to test the voltage in the shift solenoid ‘G’ control circuit.	Multimeter
Inspect Wiring and Connectors	Check the wiring and connectors for signs of wear, shorts, or corrosion.	Flashlight, Multimeter
Replace Shift Solenoid ‘G’	Replace the shift solenoid ‘G’ if it is found to be faulty.	Replacement Parts (Solenoid)
Clear the Code and Test Drive	After repairs, clear the code and take the vehicle for a test drive.	OBD-II Scanner, Vehicle Manual
Recheck for Codes	Re-scan the system to confirm the P099C code has been resolved.	OBD-II Scanner