The BMW 7-Series (E23) is the first generation of BMW’s flagship sedan, produced from 1977 to 1987. The car is designed to compete with other luxury cars in the market and is equipped with advanced features such as an onboard computer, power windows, and an automatic transmission. It is also the first BMW to feature a six-cylinder engine and a diesel engine option.
One of the essential components of the BMW 7-Series (E23) is the fuse box and relay system. These components play a critical role in protecting the electrical systems of the car, and they are responsible for controlling various functions such as lighting, heating, and air conditioning. Understanding the location and function of these components is essential for maintaining and repairing the car.
Fuse Box and Relay System
The BMW 7-Series (E23) has two fuse boxes. The main fuse box is located in the engine compartment on the left side near the firewall. It contains 12 fuses and four relays that control various functions such as the fuel pump, the cooling fan, and the horn. The secondary fuse box is located in the trunk, on the right side behind the battery. It contains eight fuses and two relays that control functions such as the rear window defroster and the power antenna.
It is essential to regularly check the fuses and relays to ensure that they are in good working condition. A blown fuse can cause a variety of electrical problems, and a faulty relay can prevent various systems from functioning correctly. The fuse and relay locations are indicated in the owner’s manual, and it is important to refer to the manual when checking or replacing these components.
Electrical Components
In addition to the fuse box and relay system, the BMW 7-Series (E23) has various other electrical components that require regular maintenance and inspection. The car’s charging system, consisting of the alternator and battery, should be checked regularly to ensure that the battery is being charged correctly. The starter motor should also be inspected to ensure that it is functioning correctly.
Other electrical components that require regular inspection include the car’s lighting system, including the headlights, taillights, and turn signals, as well as the heating and air conditioning systems. The onboard computer, which controls various functions of the car, should also be checked regularly to ensure that it is functioning correctly.
(1977-1987) BMW 7-Series (E23) fuse box and relay with Diagram
WARNING
- Never replace a fuse with one that has a higher amperage rating.
- A fuse with a too-high amperage could damage the electrical part and cause a fire.
- On no account should fuses be repaired (e.g. patched up with tin foil or wire) as this may cause serious damage elsewhere in the electrical circuit or cause a fire.
- If a fuse blows repeatedly, do not keep replacing it. Instead, have the cause for the repeated short circuit or overload tracked and fixed.
BMW 7-Series (E23) 1977-1987 fuse assignment
Fuse Box (up to 1982)
| No. | Amps | Assignment/Designation |
| 1 | 16A | Fuel Delivery/Evaporative Control Idle Speed Control |
| 2 | 8A | Headlights (RH Low Beam) |
| 3 | 8A | Headlights (LH Low Beam) |
| 4 | 25A | Cigar Lighters |
| 5 | 8A | Active Check Control Auto-Charging Flashlight Central Locking Gauges Glove Box Light Heated Door Lock Ignition Key Warning/Seatbelt Warning Interior Lights Lights: Turn/Hazard Warning On-Board Computer Radio/Power Antenna Trunk Light |
| 6 | 8A | Active Check Control Backup Lights/Transmission Range Lights Brake Lining Warning Cruise Control Dash Lights Gauges Idle Speed Control Interior Lights Power Mirrors Power Windows Seatbelt Warning Speedometer Warning Indicators |
| 7 | 8A | Headlights (LH, RH High Beams) |
| 8 | 8A | Headlights (LH, RH High Beams) |
| 9 | 8A | Active Check Control Dash Lights Lights: Front Park/Tail/Underhood Lights: Rear Marker/License |
| 10 | 8A | Active Check Control Lights: Front Park/Tail |
| 11 | 16A | Active Check Control Horns Lights: Turn/Hazard Warning Wiper/Washer |
| 12 | 8A | Active Check Control Radio/Power Antenna Stoplights/Cruise Control Warning Indicators |
| 13 | 25A | Rear Defogger/Sunroof |
| 14 | 25A | Automatic Heater-Air Conditioner Auxiliary Fan Vacuum Pump |
| 15 | 8A | Fog Lights (RH) |
| 16 | 8A | Fog Lights (LH) |
| 17 | 25A | Auxiliary Fan |
| Relay | ||
| R1 | Fuel Pump Relay | |
| R2 | Auxiliary Fan Relay (Speed 1) | |
| R3 | Low Beam Check Relay | |
| R4 | Purge Valve Relay | |
| R5 | High Beam Relay | |
| R6 | Horn Relay | |
| R7 | Low Beam Relay | |
| R8 | Fog Light Relay | |
| R9 | Unloader Relay | |
| Amps | Assignment/Designation | |
| Auxiliary Fan Fuses(2) | 25A | Auxiliary Fan |
Under Dash, Left Of Console
| Amps | Assignment/Designation | |
| Power Window Circuit Breaker | 25A | Power Windows |
| Amps | Assignment/Designation | |
| In-Line Radio | 1A | Radio |
Fuse Box (from 1982)
| No. | Amps | Assignment/Designation |
| 1 | 15A | Headlights (Left High Beam, Right Low Beam) |
| 2 | 15A | Headlights (Right High Beam, Left Low Beam) |
| 3 | 15A | Auxiliary Fan 91° C (196° F) |
| 4 | 15A | Lights: Turn/Hazard Warning |
| 5 | 30A | Wiper/Washer, Windshield Washer Jet Heaters |
| 6 | 7.5A | Active Check Control, Stop Lights/Cruise Control/Map Light |
| 7 | 15A | Horn |
| 8 | – | Not Used |
| 9 | 15A | Back Up Lights, Fuel Control (Engine Electrical Equipment) |
| 10 | 7.5A | Active Check Control, Brake Lining Warning, On-Board Computer, Seatbelt Warning, Service Interval Indicator, Speedometer/Gauges/Warning Indicators |
| 11 | 15A | Fuel Delivery (Main and Auxiliary Fuel Pump) |
| 12 | 7.5A | Active Check Control, On-Board Computer, Radio (Radio In-Line Fuse), Warning Indicators |
| 13 | 7.5A | Headlights (Left Low Beam) |
| 14 | 7.5A | Headlights (Right Low Beam) |
| 15 | – | Not Used |
| 16 | 30A | Auxiliary Fan, Vacuum Pump, Heater/Air Conditioning |
| 17 | 15A | Heater/Air Conditioning, Interior Lights, Power Mirrors, Power Windows, Seatbelt Warning, Stop Lights/Cruise Control, Windshield Washer Jet Heaters |
| 18 | 30A | Auxiliary fan 99° C (210° F) |
| 19 | 30A | Sunroof, Heated Seats |
| 20 | 30A | Hear Defogger |
| 21 | 7.5A | Active Check Control, Auto-Charging Flashlight, Gauges, Glove Box Light, interior Lights, On-Board Computer, Radio, Service Interval Indicator, Trunk Lights, Seat Belt Buzzer, Memory, Clock |
| 22 | 7.5A | Active Check Control, Lights: Front Park/Tail |
| 23 | 7.5A | Active Check Control, Rear Defogger, Lights: Front Park/Tail Underhood, Lights: Visor/Dash, Lights: Rear Marker, Lights: Turn/Hazard Warning, Engine Compartment Light, License Plate Lights |
| 24 | 15A | Lights: Turn/Hazard Warning, Open Door Buzzer |
| 25 | – | Not Used |
| 26 | 30A | Power Seats, Power Windows |
| 27 | 30A | Central Locking, Heated Door Lock, On-Board Computer, Burglar Alarm |
| 28 | 30A | Cigar Lighter, Power Antenna (Radio In-Line Fuse) |
| 29 | 7.5A | Fog Lights (Left Fog Light) |
| 30 | 7.5A | Fog Lights (Right Fog Light) |
| 32 | 30A | Accessory Fuse (Not Used) |
| 33 | 30A | Accessory Fuse (Not Used) |
| Relay | ||
| R1 | Fuel Pump Relay | |
| R2 | Wiper Control Unit | |
| R3 | Low Beam Check Relay | |
| R4 | Low Beam Relay | |
| R5 | High Beam Relay | |
| R6 | Horn Relay | |
| R7 | Auxiliary Fan Relay (Speed 1) | |
| R8 | Fog Light Relay | |
| R9 | Unloader Relay (Rear Window Defogger, Power Sliding Roof, Heated Seat) | |
| R10 | Auxiliary Fan Relay (Speed 2) | |
| R11 | Unloader Relay (Heater Blower) | |
| R12 | Oxygen Sensor Heater Relay | |
| Amps | Assignment/Designation | |
| Power Window Circuit Breaker | 25A | Power Windows |
Flasher (Turn/Hazard Warning; From 1982 Models)
Remove and install steering column casing 32 31 020.
Flasher (Turn/Hazard Warning; Up To 1982 Models)
Detach and attach instrument panel trim at the bottom left 51 45 180.
Fan Relay
- Relay For Extra Fan – Stage 1
- Relay For Extra Fan – Stage 2
Starter Repeat Limit Relay
Window Control Relay
Detach and attach instrument panel trim at the bottom left 51 45 180.
Relays For ABS On Hydraulic Unit
Unscrew bolt (1). Pull off the cover.
Pull out motor relay (2) and/or valve relay (3).
Main Relay (Up To 1982)
Main Relay (From 1982)
Blower Relay, Compressor Relay
The BMW 7-Series (E23) is a groundbreaking car that set the standard for luxury sedans. Its advanced features and sophisticated design made it popular among car enthusiasts. However, maintaining and repairing this complex car requires knowledge of its electrical systems, including the fuse box and relay system.
Regular maintenance and inspection of the electrical components of the BMW 7-Series (E23) is essential for ensuring that the car functions correctly and remains reliable. It is recommended to refer to the owner’s manual when checking and replacing these components, and to seek the help of a professional mechanic for any complex repairs. With proper care and attention, the BMW 7-Series (E23) can continue to provide a luxurious and enjoyable driving experience for years to come.
