Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Code 66, 3-2 Control Solenoid CKT Fault 4L60-E Transmission: Notes
The 3-2 control solenoid hydraulically coordinates apply rate of 2-4 band with hydraulic release of 3-4 clutch during a 3-2 downshift. The 3-2 circuit duty cycle is continually monitored by control module depending one command state of circuit. When transmission is in 1st gear, duty cycle of solenoid is equal to zero. When transmission is in 2nd gear or higher, duty cycle of solenoid will be about 90 percent. When transmission downshifts 3-2, duty cycle of solenoid will be about 20 percent.
- This test checks 3-2 control solenoid and internal transmission harness for short circuits.
- This test checks for power, from ignition through fuse, to 3-2 control solenoid.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.