Alfa Romeo 166 is a flagship sedan manufactured by Italian automaker Alfa Romeo from 1998 to 2007. The vehicle is designed by Walter de Silva and is built on the Type Three platform, shared with the Lancia Kappa and the Fiat Croma. The Alfa Romeo 166 is a successor to the 164 models, and it is offered with a range of engines and trim levels to suit different customer preferences.
One important aspect of the Alfa Romeo 166 is its electrical system, which includes a fuse box and relay that play critical roles in the car’s operation. In this article, we will explore the different electrical components of the Alfa Romeo 166, including the fuse box and relay, and how they contribute to the car’s functionality.
Alfa Romeo 166 Electrical System
The Alfa Romeo 166 features an advanced electrical system that includes a fuse box and relay. The fuse box contains fuses that protect different circuits in the car from overloading or short-circuiting. The fuses in the Alfa Romeo 166 are color-coded, and each color represents a different amperage rating. A blown fuse can cause a specific system to stop working, and it is essential to replace the faulty fuse with a new one of the same amperage rating.
The relay, on the other hand, is an electrical switch that controls the operation of various systems in the car, such as the fuel pump, headlights, and windshield wipers. The relay works by receiving a signal from a switch or sensor and then using an electromagnet to open or close a circuit. A faulty relay can cause various systems to malfunction or stop working, and it is crucial to replace a bad relay promptly. The fuse box and relay are located in the engine compartment, and their location may vary slightly depending on the year and model of the Alfa Romeo 166.
(1998-2007) Alfa Romeo 166 fuse box and relay with Diagram
Fuse Location (1998-2003)
This model is fitted with two junction units: a main junction unit (1) located underneath the dashboard to the left of the steering column and an auxiliary junction unit (2) positioned in the engine compartment.
Fuse Location (2003-2007)
This model is fitted with three junction units: one (1) located underneath the dashboard to the left of the steering column, one (2) located in the engine compartment and a third (3) in the boot. In addition, the power supplies coming from the battery are protected by MAXIFUSES located on the actual battery.
Passenger Compartment Fuse Box
Access to it is gained slackening the knob (A) and lowering the panel (B).
| No. | Amps | Assignment/Designation |
| 1 | 15A | Brake Lights, IGE Control Unit, Brake Depressed Light Control Signal, Control Panel, Direction Indicators (Steering Column Switch Unit), Exterior Lights Control |
| 2 | 10A | Air Bag Control Unit, Gearshift Lever |
| 3 | 5A | ’03-’07: Sun Roof, Rear Socket, Seats |
| ? | Fuel Pump | |
| 4 | 15A | Radio |
| 5 | 10A | Mobile Phone, Glove Compartment Light, Cruise Control, Gear Lever Panel (CAE), Light Dimmer, Door Opening Receiver, Heated, Fold-Down Door Mirrors, Antitheft Control Unit, Switch On Console (C.M.), Compressor Relay Coil, Symbols (Switches/Buttons), I.C.S. System, Sound System Controls on Steering Wheel |
| 6 | 7.5A | ’03-’07: Control Panel, Control Lighting, Headlights and Headlight Position Sensor (Gas Discharge Headlights), I.C.S. System |
| 5A | ’98-’03: Climate Control Fan Relay Coil | |
| 7 | 10A | Front Current Socket (Cigar Lighter), I.C.S. System |
| 8 | 10A | Direction Indicators and Hazard Warning Lights, Right Side Lights |
| 9 | 5A | ’03-’07: Control Lighting, Brake Lights Switch, IGE Control Unit, ABS |
| 5A | ’98-’03: Electrochromic Mirror, Rain Sensor, Preparation for Telepass, Relay Coil for Seat Heat Pad Control, Signal to Front Electric Window Control Unit, Signal to Rear Electric Window Control Unit, Climate System Controls, Rear Electric Window Switch Inhibition Light | |
| 10 | 5A | CAE Control Unit, Electronic Automatic Gearbox (Control Unit, Sensors and Gearshift Lever) |
| 11 | 15A | ’03-’07: IGE Control Unit, Headlight Spot |
| 20A | ’98-’03: IGE Control Unit | |
| 12 | 20A | Headlamp Washer |
| 13 | 10A | ’03-’07: Sun Roof, ABI Control Unit, Electronic Automatic Gearbox, Reversing Lights (only Versions with Manual Gearbox) |
| 15A | ’98-’03: Sun Roof, Reversing Light Signal for Electrochromic Mirror | |
| 14 | 25A | Windscreen Wash/Wiper |
| 15 | 10A | ’03-’07: IGE Control Unit, Rear Light Units |
| 25A | ’98-’03: Motor for Right/Left Front Electric Windows | |
| 16 | 5A | Alfa Romeo Code System, Electronic Injection System, Engine Cooling Control Unit, Compressor Relay, Electronic Automatic Gearbox, Fuel Pump Relay Coil (Engine Bay Box) |
| 17 | 10A | ’03-’07: IGE Control Unit, Left Side Lights |
| 10A | ’98-’03: Transmission Lever Panel (CAE), Passegner Compartment Courtesy Light, Door Lights, Boot Light, Glove Compartment Light, Light Dimmer, Climate Control System Control Unit, Antitheft Control Unit, Remote Control Receiver, Diagnostic Socket | |
| 18 | 5A | Instrument Panel, I.C.S. System, Preparation for Mobile Phone, EOBD System (Diagnostic Socket), Navigator |
| 19 | 5A | ’03-’07: Climate Control System Control Unit |
| 25A | ’98-’03: Central Locking Motor, Additional Current Socket | |
| 20 | 5A | Alfa Romeo Code System- Injection (Petrol) |
| Relay | ||
| R1 | Ignition Discharge | |
| R2 | ’98-’03: Direction Indicators/Hazard Warning Lights Flasher | |
| R3 | Headlamp Washer Intermittent | |
Engine Compartment Fuse Box (1998-2003)
| No. | Amps | Assignment/Designation |
| 1 | 10A | Right Main Beam Headlamp |
| 2 | 10A | Left Main Beam Headlamp |
| 3 | 15A | Fog Light |
| 4 | 15A | Horns |
| 5 | 10A | Air Conditioning Compressor |
| 6 | 10A | Left Dipped Headlamp |
| 7 | 10A | Right Dipped Headlamp |
| 8 | 50A | High Speed Radiator Fan |
| 9 | 50A | Low Speed Radiator Fan |
| Relay | ||
| R1 | Dipped Beam Headlamps | |
| R2 | Horns | |
| R3 | Air Conditioning Compressor | |
| R4 | Main Beam Headlamps | |
| R5 | Fog Light | |
| R6 | High Speed Radiator Fan | |
| R7 | Low Speed Radiator Fan | |
Additional Fuses (1998-2003)
| No. | Amps | Assignment/Designation |
| 1 | 80A | JTD: Plug Preheating Control Unit |
| 2 | 30A | Ignition Coils, Fuel Injection Main Relay, Fuel Pump Relay, Engine Management Control Unit, Fuel Injection Control Unit Supply Relay, Fuel Injection Services Supply Fuse |
| 3 | 30A | JTD: Additional Heater |
| 4 | 15A | JTD: Diesel Pre-Heating |
| 5 | 30A | Starter |
| 7 | 60A | ABS |
| 8 | 40A | ’01-’03: Radiator Fan (2.4 JTD 10v – ???) |
| 9 | 30A | Vehicle Interior Fan |
| 10 | 5A | CAE Supply |
| 11 | 10A | ABS |
| 12 | 7.5A | JTD: Engine Management Control Unit |
| 13 | 20A | ’02-’03: Cigar Lighter |
Luggage Compartment Fuses (1998-2003)
| No. | Amps | Assignment/Designation |
| 1 | 40A | Heated Rear Window |
| 2 | 25A | Fuel Flap Opening |
| 3 | 20A | Boot Opening |
| 4 | 30A | Left Seat Adjustment |
| 5 | 20A | Seat Heating |
| 6 | 30A | Right Seat Adjustment |
| 7 | 15A | Trailer |
| 8 | 25A | Rear Electric Windows |
| near with Battery | ||
| – | 125A | Main Fuse |
| 150A | ’99-03 (2.4 JTD 6M): Main Fuse | |
| – | 60A | Luggage Fuses |
| ACC | 30A | Ignition Switch |
| Centr | 60A | Fuse: “8”, “10”, “11”, “12”, “15”, “17”, “18”, “19”, “20”, Ignition Discharge Relay, Vehicle Interior Fan Fuse |
| – | 15A | Radio Amplifier |
Luggage Compartment Fuse Box (2003-2007)
| No. | Amps | Assignment/Designation |
| 54 | 25A | HIFI Amplifier |
| 55 | 20A | Sun-Roof |
| 56 | 20A | Driver’s (LH) Side Front Window |
| 57 | 10A | Driver’s (LH) Heated Seat |
| 58 | – | – |
| 59 | 7.5A | Mirror Demist |
| 60 | 20A | Passenger (RH) Side Front Window |
| 20A | Rear Current Socket | |
| 61 | 20A | Left Rear Electric Window |
| 62 | 20A | Right Rear Electric Window |
| 63 | 20A | Central Locking, Boot Release |
| 64 | 30A | Heated Rear Window |
| 65 | 10A | JTD: Additional Heater |
| 66 | 10A | Anti-Theft Device and Light Blinker, Diretction Indicators, Trailer Presetting |
| 67 | 10A | Passenger (RH) Heated Seat |
| 68 | 15A | Windscreen Demisting |
| 20A | Passenger (RH) Side Front Window | |
| 69 | 20A | Rear Current Socket |
| 15A | Windscreen Heating | |
| 77 | 30A | Driver’s (LH) Seat Movement |
| 78 | 10A | Interior Lights, Rain Sensor, Mirror Adjustment, Seat Warming Control Light, Sun Vision Lights, Alarm System Control Unit, Electrochromic Driving Mirror, Parking Sensors Control Unit, Remote Control Receiver |
| 79 | 30A | Passenger (RH) Seat Movement |
| 80 | – | – |
| Relay | ||
| R21 | Sun Roof, Rear Socket | |
| R22 | Windscreen and Mirror Demisting | |
| R23 | Heated Rear Window | |
| R24 | Ignition Discharge | |
| R25 | Climate Control System Control Unit | |
| R26 | Lights Blinker | |
Engine Compartment Fuse Box (2003-2007)
| No. | Amps | Assignment/Designation |
| 1 | 50A | JTD: Glow Plugs |
| 60A | JTD: Glow Plugs | |
| 2 | 40A | ABS |
| 3 | 20A | Ignition Switch |
| 30A | Starter Motor | |
| 4 | 40A | ABS |
| 5 | 10A | CAE Ignition Lock |
| 20A | Electronic Automatic Gearbox (3.0 V6 24V Sportronic Version) | |
| 6 | 30A | Engine Cooling Fan (Low Speed) |
| 40A | Engine Cooling Fan (Low Speed) | |
| 7 | 60A | Engine Cooling Fan (High Speed) |
| 8 | 30A | Climate Control Fan |
| 9 | 15A | Electronic Automatic Gearbox – Sportronic Versions (Control Unit, Sensors and Gearshift Lever) |
| 10 | 15A | Horns |
| 11 | 15A | Electronic Injection Control Unit, Various Auxiliary Services I.E., Diesel Filter (JTD) |
| 14 | 15A | Right Main Beam Headlamp |
| 15 | 15A | Left Main Beam Headlamp, Headlamp Alignment |
| 16 | – | – |
| 17 | 10A | Electronic Injection Control Unit |
| 18 | 7.5A | Engine Control Unit, I.E. Services, CAE |
| 19 | 7.5A | Conditioner Compressor |
| 20 | 30A | JTD: Diesel Filter Heating |
| 21 | 15A | Fuel Pump |
| 22 | 20A | Electronic Injection Control Unit |
| 23 | 20A | JTD: Additional Heater |
| 24 | – | – |
| 30 | 15A | Front Fog Lights |
| Relay | ||
| R2 | High Beam | |
| R3 | Horn | |
| R5 | Compressor | |
| R6 | Radiator Fan 1st Speed | |
| R7 | Radiator Fan 2st Speed | |
| R8 | Climate Control System | |
| R9 | Fuel Injection Main | |
| R10 | Fuel Pump | |
| R14 | Fog Lamp | |
| R17 | CAE | |
| R19 | Heated Diesel Filter | |
| R20 | Starter Inhibitor | |
Engine Compartment Fuse Box No.2 (2003-2007)
| No. | Amps | Assignment/Designation |
| 4 | 70A | CPL |
| 5 | 70A | CVB |
| 6 | – | |
| 7 | 150A | CVM |
Additional Heater Relay, Cooling Fan Relay (JTD – 2003-2007)
To gain access to relays on the bracket set behind the left headlight, remove the cover (A) after turning the fastening pins (B).
Brown Relay: Additional Heater
Black Relay: Engine Cooling Radiator (High Speed)
Conclusion
The Alfa Romeo 166 is an impressive sedan that offers exceptional driving dynamics, premium features, and advanced technology. The car’s electrical system, including the fuse box and relay, plays a critical role in the vehicle’s operation and performance. Understanding how these components work and how to troubleshoot them can help keep the Alfa Romeo 166 running smoothly and prevent unnecessary breakdowns. Regular maintenance and inspections of the electrical system are essential to ensure the reliability and longevity of the Alfa Romeo 166.
