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)

alfa romeo 166 fuse location 1998 2003
alfa romeo 166 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)

alfa romeo 166 fuse location 2003 2007
alfa romeo 166 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

alfa romeo 166 1998 2003 passenger compartment fuse box
alfa romeo 166 1998 2003 passenger compartment fuse box

Access to it is gained slackening the knob (A) and lowering the panel (B).

alfa romeo 166 1998 2003 passenger compartment fuse box 2
alfa romeo 166 1998 2003 passenger compartment fuse box 2
alfa romeo 166 1998 2003 passenger compartment fuse box 02
alfa romeo 166 1998 2003 passenger compartment fuse box 02
No.AmpsAssignment/Designation
115ABrake Lights, IGE Control Unit, Brake Depressed Light Control Signal, Control Panel, Direction Indicators (Steering Column Switch Unit), Exterior Lights Control
210AAir Bag Control Unit, Gearshift Lever
35A’03-’07: Sun Roof, Rear Socket, Seats
?Fuel Pump
415ARadio
510AMobile 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
67.5A’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
710AFront Current Socket (Cigar Lighter), I.C.S. System
810ADirection Indicators and Hazard Warning Lights, Right Side Lights
95A’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
105ACAE Control Unit, Electronic Automatic Gearbox (Control Unit, Sensors and Gearshift Lever)
1115A’03-’07: IGE Control Unit, Headlight Spot
20A’98-’03: IGE Control Unit
1220AHeadlamp Washer
1310A’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
1425AWindscreen Wash/Wiper
1510A’03-’07: IGE Control Unit, Rear Light Units
25A’98-’03: Motor for Right/Left Front Electric Windows
165AAlfa Romeo Code System, Electronic Injection System, Engine Cooling Control Unit, Compressor Relay, Electronic Automatic Gearbox, Fuel Pump Relay Coil (Engine Bay Box)
1710A’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
185AInstrument Panel, I.C.S. System, Preparation for Mobile Phone, EOBD System (Diagnostic Socket), Navigator
195A’03-’07: Climate Control System Control Unit
25A’98-’03: Central Locking Motor, Additional Current Socket
205AAlfa Romeo Code System- Injection (Petrol)
Relay
R1Ignition Discharge
R2’98-’03: Direction Indicators/Hazard Warning Lights Flasher
R3Headlamp Washer Intermittent

Engine Compartment Fuse Box (1998-2003)

alfa romeo 166 1998 2003 engine compartment fuse box
alfa romeo 166 1998 2003 engine compartment fuse box
No.AmpsAssignment/Designation
110ARight Main Beam Headlamp
210ALeft Main Beam Headlamp
315AFog Light
415AHorns
510AAir Conditioning Compressor
610ALeft Dipped Headlamp
710ARight Dipped Headlamp
850AHigh Speed Radiator Fan
950ALow Speed Radiator Fan
Relay
R1Dipped Beam Headlamps
R2Horns
R3Air Conditioning Compressor
R4Main Beam Headlamps
R5Fog Light
R6High Speed Radiator Fan
R7Low Speed Radiator Fan

Additional Fuses (1998-2003)

No.AmpsAssignment/Designation
180AJTD: Plug Preheating Control Unit
230AIgnition Coils, Fuel Injection Main Relay, Fuel Pump Relay, Engine Management Control Unit, Fuel Injection Control Unit Supply Relay, Fuel Injection Services Supply Fuse
330AJTD: Additional Heater
415AJTD: Diesel Pre-Heating
530AStarter
760AABS
840A’01-’03: Radiator Fan (2.4 JTD 10v – ???)
    
930AVehicle Interior Fan 
105ACAE Supply 
1110AABS
127.5AJTD: Engine Management Control Unit
1320A’02-’03: Cigar Lighter

Luggage Compartment Fuses (1998-2003)

No.AmpsAssignment/Designation
140AHeated Rear Window
225AFuel Flap Opening 
320ABoot Opening 
430ALeft Seat Adjustment 
520ASeat Heating 
630ARight Seat Adjustment 
715ATrailer
825ARear Electric Windows 
near with Battery    
125AMain Fuse
150A’99-03 (2.4 JTD 6M): Main Fuse
60ALuggage Fuses
ACC30AIgnition Switch
Centr60AFuse: “8”, “10”, “11”, “12”, “15”, “17”, “18”, “19”, “20”, Ignition Discharge Relay, Vehicle Interior Fan Fuse
15ARadio Amplifier

Luggage Compartment Fuse Box (2003-2007)

alfa romeo 166 2003 2007 luggage compartment fuse box
alfa romeo 166 2003 2007 luggage compartment fuse box
alfa romeo 166 2003 2007 luggage compartment fuse box 2
alfa romeo 166 2003 2007 luggage compartment fuse box 2
No.AmpsAssignment/Designation
5425AHIFI Amplifier
5520ASun-Roof
5620ADriver’s (LH) Side Front Window
5710ADriver’s (LH) Heated Seat
58 –
597.5AMirror Demist
6020APassenger (RH) Side Front Window
20ARear Current Socket
6120ALeft Rear Electric Window
6220ARight Rear Electric Window
6320ACentral Locking, Boot Release
6430AHeated Rear Window
6510AJTD: Additional Heater
6610AAnti-Theft Device and Light Blinker, Diretction Indicators, Trailer Presetting
6710APassenger (RH) Heated Seat
6815AWindscreen Demisting
20APassenger (RH) Side Front Window
6920ARear Current Socket
15AWindscreen Heating
7730ADriver’s (LH) Seat Movement
7810AInterior 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
7930APassenger (RH) Seat Movement
80 –
Relay
R21Sun Roof, Rear Socket
R22Windscreen and Mirror Demisting
R23Heated Rear Window
R24Ignition Discharge
R25Climate Control System Control Unit
R26Lights Blinker

Engine Compartment Fuse Box (2003-2007)

alfa romeo 166 2003 2007 engine compartment fuse box
alfa romeo 166 2003 2007 engine compartment fuse box
alfa romeo 166 2003 2007 engine compartment fuse box 2
alfa romeo 166 2003 2007 engine compartment fuse box 2
No.AmpsAssignment/Designation
150AJTD: Glow Plugs
60AJTD: Glow Plugs
240AABS
320AIgnition Switch
30AStarter Motor
440AABS
510ACAE Ignition Lock
20AElectronic Automatic Gearbox (3.0 V6 24V Sportronic Version)
630AEngine Cooling Fan (Low Speed)
40AEngine Cooling Fan (Low Speed)
760AEngine Cooling Fan (High Speed)
830AClimate Control Fan
915AElectronic Automatic Gearbox – Sportronic Versions (Control Unit, Sensors and Gearshift Lever)
1015AHorns
1115AElectronic Injection Control Unit, Various Auxiliary Services I.E., Diesel Filter (JTD)
1415ARight Main Beam Headlamp
1515ALeft Main Beam Headlamp, Headlamp Alignment
16 –
1710AElectronic Injection Control Unit
187.5AEngine Control Unit, I.E. Services, CAE
197.5AConditioner Compressor
2030AJTD: Diesel Filter Heating
2115AFuel Pump
2220AElectronic Injection Control Unit
2320AJTD: Additional Heater
24 –
3015AFront Fog Lights
Relay
R2High Beam
R3Horn
R5Compressor
R6Radiator Fan 1st Speed
R7Radiator Fan 2st Speed
R8Climate Control System
R9Fuel Injection Main
R10Fuel Pump
R14Fog Lamp
R17CAE
R19Heated Diesel Filter
R20Starter Inhibitor

Engine Compartment Fuse Box No.2 (2003-2007)

alfa romeo 166 2003 2007 engine compartment fuse box 02
alfa romeo 166 2003 2007 engine compartment fuse box 02
No.AmpsAssignment/Designation
470ACPL
570ACVB
6
7150ACVM

Additional Heater Relay, Cooling Fan Relay (JTD – 2003-2007)

alfa romeo 166 2003 2007 relays
alfa romeo 166 2003 2007 relays

To gain access to relays on the bracket set behind the left headlight, remove the cover (A) after turning the fastening pins (B).

alfa romeo 166 2003 2007 relays 2
alfa romeo 166 2003 2007 relays 2

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.

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