Code 12 (Magnetic Clutch Circuit)

Code 12 sets if magnetic clutch circuit is open or shorted to ground.

1. Disconnect electrical connector from actuator motor. Manually move control plate on actuator back and forth. If control plate does not move freely, replace actuator. If control plate moves freely, turn magnetic clutch on by applying battery voltage to actuator connector terminals No. 5 (positive lead) and No. 4 (negative lead). See Fig 1.
2. Try to move control plate. If control plate moves, replace actuator. If control plate does not move, disconnect electrical connector from stoplight switch. With brake pedal pressed, there should be continuity between terminals No. 1 and 2, and no continuity between terminals No. 3 and 4. See Fig 2.
3. With brake pedal released, there should be continuity between terminals No. 3 and 4, and no continuity between terminals No. 1 and 2. If continuity is not as specified, replace stoplight switch. If continuity is as specified, check for faulty circuit between following: cruise control ECU and stoplight switch; stoplight switch and actuator; actuator and ground.
4. If circuit is okay:
   • CODE - Replace cruise control ECU
   • NO CODE - Perform next procedure listed in DIAGNOSIS BY SYMPTOM  table.

Fig 1: Testing Magnetic Clutch

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Fig 2: Identifying Stoplight Switch Connector Terminals

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002