300ZX Electronic Lock-Up & Overdrive Control

1. Operation of torque converter lock-up and overdrive (D4) is handled by electronic control unit (ECU), located on floor near driver's seat. ECU will activate lock up solenoid in all forward ranges if conditions are correct. Either "standard" or "power" shift pattern is selected by ECU depending upon rate at which accelerator is depressed.
2. Vehicle speed and throttle position are both inputs to ECU. Power shift switch activates overdrive cancel solenoid when turned off and transmission will not shift into D4 range. If lock-up or overdrive malfunction, test lock-up control unit first. See Fig 1.
3. Testing is to be performed with wiring harness connected to ECU. Using voltmeter, check voltage between terminal No. 22 (Ground) and each terminal as listed in test chart. If ECU tests properly, proceed to lock-up, overdrive, downshift, shift pattern change, A.S.C.D. (Automatic Speed Control Device), and kickdown control testing as shown in flow charts and associated text. See Fig 2-Fig 7 .
4. Terminal No. 20 is not used on ECU connector. Terminal No. 1 is directly above No. 6. Top row of connector contains terminals 1-17, viewed from front. Bottom row contains terminals 6-22. See WIRING DIAGRAMS .

Fig 1: Electronic Lock-Up Control Unit Test Chart (300ZX)

Fig 2: Lock-Up Control Inspection Points (300ZX)

Fig 3: Downshift Control Inspection Points (300ZX)

Fig 4: Kickdown Control Inspection Points (300ZX)

Fig 5: Shift Pattern Change Control Inspection (300ZX)

Fig 6: A.S.C.D. Parts Inspection Points (300ZX)

Fig 7: Overdrive Control Inspection Points (300ZX)