Electrical

For most people, the Electrical system is the scariest part of the car. All those wires, and the magical force of electricity, can be very confusing. But dry your eyes mate, we'll get you through it.

Engine

All of the main functions of the engine; the Fuel, Air and Spark, are ultimately controlled electrically.

ECU

Main article: ECU

The brain of your car, the ECU is in control of engine running. It takes readings from sensors scattered around the engine bay, and adjusts the fueling accordingly.

Charging

Main article: Charging

To keep everything running, your system needs to generate electricity as it's used. To do that your car has an alternator, driven by a belt from the engine. The alternator is directly connected to the main distribution circuit, as well as to the battery to keep that topped and fresh.

Loom

Main article: Loom

The loom is one enormous snake of wires, and is a one-piece unit in E30s. From the very back of the car all the way to the fuse box, it feeds every primary and ancillary circuit in the vehicle, with only a small number of plug-in extras to feed things like the OBC and cruise control.

The same loom was used in all cars for any specific year, but there are small differences between years. The biggest difference is between facelift (1987-94) and pre-facelift (82-87) cars, when a large number of modifications were made to various systems throughout the vehicle. There are also important differences to Touring and Cabriolet models, since they have features not fitted to standard saloons.

If you want to know more about any particular aspect of the loom, check out our wiring diagrams.

Interior

Instruments

Main article: Instruments

Sticking your hand out of the window and wiggling it in the slipstream isn't a very accurate way of measuring speed. For that reason, your car is kitted out with all manner of dials, clocks and gauges to keep you informed of how the car is working.

These instruments are all contained in the Dash Cluster, which is fed by three main wires from the Loom. While clusters can be swapped between vehicles, they contain a special chip or Coding Plug that tells the instruments what engine is fitted to the car. Fitting the wrong coding plug will give massively incorrect readings for the instruments.

An extra unit, known as the On-Board Computer or OBC, was also available. These units good give you simple time and temperature functions, while more advanced units had access to fuel economy and range data.

Stereo

Main article: Audio

While the noise of the engine should be all you need when driving an E30, many people want some phat sounds while driving, to while away the motorway miles.

The E30 was available with a wide range of stereo head units from the factory, and all of the wiring is in place to fit four speakers within the cabin. There is also extra wiring provided for tweeter pods, which fit into the front doors.

All of the stereo wiring is a one-piece accessory loom using a standard BMW colour coding system, and isn't really compatible with more modern stereos. Because of that, most cars have had their wiring butchered and chopped over the past two decades by enthusiastic teens and ill-informed installers, so the current state of your stereo system could be a complete mystery.

Exterior

Lights

Main article: Lights

Windows

Main article: Windows

Wing Mirrors

Main article: Wing Mirrors

Locks

Main article: Central Locking

Sunroof

Main article: Sunroof

While poverty-specification vehicles came with a windy handle to open and close the roof, some buyers opted for the electric alternative. Mounted in the roof and activated with a switch above the driver's head, the motor offered two functions; upward tilt and full recline.

If you have an "exercise roof", all of the wiring should be in place to fit the electric motor and switch to upgrade your sunroof.

Rear Demister

If you want to make your Demister switch glow like the Hazard and Wiper switches, then learn more about illuminating your demister switch.

Ancilliaries

Cruise Control

Main article: Cruise Control

Heated

The term Heated can be applied to a number of accessories on the E30. The list of heated features includes:

• Heated Seats
• Heated Wing Mirrors
• Heated Washer Jets
• Heated Door Locks

The main Loom provides plugs for all of these accessories in their respective locations, but there are no switches; all heated components except the Seats are activated automatically when the ignition is turned on.

If you feel the need to prepare your car for cold weather climes, then learn more about retrofitting heated washer jets.

Common Problems

Central locking: It is very common for E30s to develop issues with their central locking. This is caused by a constant live power source running through the door which, over time, causes the terminals in the door loom to corrode. This has a simple fix which all E30s can benefit from.