4. Controls

The automatic transmission controls include the selector lever cable, the accelerator cable, the throttle cable, and beginning in 1990 the automatic shift lock. The selector lever cable allows the transmission to be manually shifted from inside the passenger compartment. The accelerator cable and the throttle cable make the transmission responsive to throttle position. The automatic shift lock prevents the transmission from being shifted out of P or N unless the brake pedal is depressed.

The selector lever cable activates the manual valve on the transmission. When the lever is moved out of park, the parking mechanism is released and the manual valve is correctly positioned according to the gear selected.

The selector lever cable and related parts are shown in Fig. 4-1. The neutral/park/reverse light switch prevents the car from starting when the selector lever is in gear. The switch also actuates the reverse lights when the selector lever is in reverse.

On models with automatic shift lock, the shift-lock solenoid actuates the shift-lock plate to prevent the shift-lever release button from being depressed. The solenoid is controlled by a relay, which receives a signal from the brake light switch. See ELECTRICAL SYSTEM for information on electrical tests of the automatic shift lock or neutral/park/reverse light switch.

Fig. 4-1.

Exploded view of automatic transmission selector lever and related parts. Inset shows end of cable which attaches to transmission operating lever.

The accelerator cable and the throttle cable are connected to an operating lever on the side of the transmission. This operating lever controls both the movement of the throttle and the engagement of the kickdown valve. The lever is connected to a shaft which runs through the center of the manual valve. On the opposite end of the shaft is the operating lever for the kickdown valve.

The accelerator and throttle cables are shown in Fig. 4-2. When the accelerator pedal is depressed the accelerator cable changes the position of the operating levers, which in turn change the position of the throttle valve (gasoline engines) or the speed control lever (diesel engines) via the throttle cable. The kickdown device allows for maximum acceleration when the accelerator pedal is fully depressed either by downshifting to a lower gear or by delaying the shift into a higher gear.

Fig. 4-2.

Accelerator and throttle cable layout used with gasoline engine with automatic transmission. Arrows show movement of operating levers as accelerator pedal is depressed. Diesel engine with automatic transmission is similar.