Cruise control – circuit operation

CRUISE CONTROL – CIRCUIT OPERATION

CIRCUIT OPERATION

Cruise Control Switch (MFI-V8) (MFI-T16) (300 Tdi without EDC) With the Cruise Control Switch (X115) on, voltage from Fuse F18 is applied to the Cruise Control ECU (2121), Cruise Control Lockout Relay (K110) (Automatic), Speed Trip Module (2164) (Manual), and the Steering Wheel Cruise Switches (X266) through the WY wire, Rotary Coupler (Z104) and PB wire. The Cruise Control ECU (Z121) is grounded at terminal 8 through the B wire to E201.

Cruise Control Switch (300 Tdi with EDC) With the Ignition Switch (X134) in position Il, battery voltage is applied to the Cruise Control Switch (X115) through the closed switch contacts of the Cruise Control Disable Relay (K234). The Engine Control Module (ECM) (Z132) applies ground to the coil of the Cruise Control Disable Relay (K234) if an engine fault is detected. The relay energises, opening the switch contacts. The battery supply to the Cruise Control Switch (X115) is interrupted, disabling the Cruise Control System.

With the Cruise Control Switch (X115) on, voltage from Fuse F18 is applied to the Cruise Control ECU (2121), Cruise Control Lockout Relay (K110) (Automatic), Speed Trip Module (Z164) (Manual), and the Steering Wheel Cruise Switches (X266) through the WY wire, Rotary Coupler (Z104) and PB wire. The Cruise Control ECU (Z121) is grounded at terminal 8 through the B wire to E201.

Cruise Control Vacuum Pump (M103) With the Cruise Control Switch (X115) on, voltage is applied to the Cruise Control Vacuum Pump (M103) through the WU wire. When a cruise speed is set, the Cruise Control ECU (Z121) applies ground through the BR wire to operate the pump motor and applies ground through the BY wire to close the normally open solenoid valve in the pump. The pump applies vacuum to the actuator.

SET/ACCEL

To set a cruise speed, the Cruise Control Switch (X115) must be on and vehicle speed must exceed 28 mph (45 km/h). When the SET/ACCEL Switch is depressed under these conditions, voltage from Fuse F18 is applied to terminal 3 of the Cruise Control ECU (Z121) through the closed Cruise

CRUISE CONTROL B5

Control Switch (X115) and Steering Wheel Cruise Switches (X266), causing the vacuum pump to operate. When the SET/ACCEL Switch is released, voltage is removed from terminal 3, signalling the ECU to set the speed.

RES/DECEL When the RES/DECEL Switch is depressed, voltage is applied to terminal 4 of the Cruise Control ECU (£121). This voltage signals the ECU to disengage th dth hicle sl When th © system and the vehicle slows down. When the switch is depressed a second time, voltage is again applied to the ECU and the vehicle returns to the previously set speed.

CIRCUIT OPERATION 1