Lock-Up & Overdrive Control

Operation of torque converter lock-up and overdrive is determined by Lock-Up Control Unit (LCU), located on floor near driver seat. LCU, with various sensors, EFI (Electronic Fuel Injection) and ASCD (Automatic Speed Control Device) control units, will activate lock-up and overdrive under predetermined conditions. See WIRING DIAGRAMS .
Either "standard" or "power" shift pattern is selected by LCU, depending upon rate at which accelerator is depressed. If malfunction of lock-up or overdrive, test lock-up control unit first. See Figure .
Testing is to be performed with wiring harness connected to LCU. Using voltmeter, check voltage between terminal No. 22 (Ground) and each terminal as listed in test chart. Fig 1 . If LCU tests properly, see appropriate INSPECTION POINTS chart. See Fig 2 -Fig 5 . Terminal No. 20 and No. 14 are not used.

Fig 1: LCU Connector Identification (300ZX)

Courtesy of NISSAN MOTOR CO., U.S.A.

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

Fig 3: Kickdown Control Inspection Points (300ZX)

Fig 4: A.S.C.D. Parts Inspection Points (300ZX)

Fig 5: Overdrive Control Inspection Points (300ZX)