A/T Lock-Up Relay (A/T)

Battery voltage is supplied to lock-up relay Light Green/Red wire from control relay. Battery voltage is also supplied to lock-up relay through stoplight switch. Voltage through stoplight switch should drop to zero volts when brake pedal is depressed. When ECM senses conditions are correct for energizing lock-up solenoid in automatic transmission, ECM will energize lock-up relay by providing a ground.

Lock-up relay is energized and provides current to the lock-up solenoid. When lock-up solenoid is energized, lock-up solenoid sends reference signal to ECM to confirm solenoid operation. Lock-up solenoid will provide oil pressure to torque converter clutch under the following conditions:

• A/T oil pressure switch is on
• Brake pedal is released and stoplight switch is on
• Coolant temperature is greater than 140°F (60°C)
• Throttle valve opening is greater than 7 degrees and less than 62 degrees