200SX Lock-Up & Overdrive Control
- Operation of torque converter lock-up and overdrive (D4) is handled by ECU that senses vehicle speed. ECU will activate lock-up solenoid if conditions are correct. Overdrive control switch activates overdrive cancel solenoid when turned off and transmission can not shift into D4 range.
- If lock-up or overdrive malfunction, perform Lock-Up Control Unit Test first. See Fig 1. If ECU tests properly, proceed to lock-up control testing and 3rd/overdrive control testing as shown in flow charts and associated text. See Fig 2 and Fig 3
- ECU is located in left side of luggage compartment on hatchback models; on coupe models, it is located behind right panel in rear seat area. Testing is to be performed with wiring harness connected to ECU. Using voltmeter, check voltage between terminal No. 5 (Ground) and each terminal as listed in test chart.
- No. 6 terminal is not used on ECU connector. No. 1 terminal is directly above No. 6. Upper row of connector contains terminals 1-5, counting left to right viewed from front. Lower row contains terminals 6-10. See WIRING DIAGRAMS .