Cruise control is one of the most comfortable features for long drives. The advantage of an original kit is that it integrates directly into the instrument cluster and the car's own throttle lever.

Control unit (Box): E.g., Volvo 3501472 / Hella 5GA 004 872-22. Vacuum pump: Usually located in the engine compartment (e.g., in the driver's side inner fender). Vacuum gauge and cable: Pulls the throttle valve. Three-part cable pulley: Replaces the original simple pulley. Brake pedal switch: Electrical and vacuum-based safety cutoff. Turn signal stalk switch: Turn signal stalk with Cruise buttons.

In an automatic transmission car, the pulley must rotate three different cables. The correct order looking away from the throttle valve: Closest to throttle valve: Kick-down cable (for automatic gearbox). Middle: Throttle cable (from pedal). Outermost: Vacuum gauge cable (from cruise control). Note: The vacuum gauge's mounting bracket goes on the intake manifold between the throttle valve and firewall. If the bracket is not perfectly aligned with the pulley, you will have to modify it or make a spacer bracket so the cable doesn't rub through.

The kit's wiring harness typically has four loose leads that must be connected to the car's electrical system: Speed signal: Taken from behind the instrument cluster. Find a connector with a speed signal (often white/green wire or marked pin behind the cluster). Brake pedal: Connected to the brake light switch. This must cut off the control immediately when the brake is applied. Power (+12V): From ignition switch (via fuse) so the device works only with ignition on. Ground: A solid point on the car's frame.

Pump: Mount the pump with vibration isolation in the engine compartment. Tubing: Run vacuum tubing from pump to the brake pedal valve and then to the intake manifold's vacuum gauge. Principle: When you apply the brake, the pedal valve admits ambient air into the system, which mechanically releases throttle immediately, even if electrics fail.

The 940's cruise control can be diagnosed through the engine compartment diagnostic box (pin B2), if it is a newer electrical system. If the control doesn't engage, first check for vacuum leaks. Even a tiny hole in the hose or a loose connection at the brake pedal valve prevents the control from pulling throttle. Another common fault is a faulty brake light switch or a brake pedal valve set incorrectly, which thinks the brake is continuously on.