Relays

As a key part of the Loom, a number of relays are fitted to various parts of your Electrical system. The most important relays, K1-K10, are located inside the Fuse Box.

The basic idea of a relay is an electromagnetic switch, which sits between two circuits; an input circuit and an output circuit. On the most basic relays, turning on the input circuit will also turn on the output circuit. In this way, small, low-power wires can go to all the controls in the car, and the big dangerous high-power wires can stay out of harms way.

But relays can do more than that. Sometimes turning on the input circuit turns off the output circuit, or even switches between two different outputs, turning very simple controls into much more complicated wiring puzzles.

Because of this, the relay can sometimes cause problems in a circuit. Knowing where the relay is will be the first step in curing the problem, so here's a map to all the relays fitted to your E30, outside the fuse box:

Function	Relay	Location
Headlight Cleaners	1
Intensive Cleaning	2
DME	3
Cruise Control	4
Idle Speed	5
Ignition Advance	6
Igntion Control	7
Fuel Pump	8
Oxygen Sensor heating	9
AC Blower	10
AC	11
Flashing relay	12
ABS Overvoltage	13
ABS Control	14
Hydraulic Control	15
Valve relay	16
Motor relay	17
Ignition advance (up to 1987)	18
Idle stabilisation	19
L-Jetronic Master relay	20
Alarm system relay	21
Power Window relay	22
Starter interlocking relay	23
Central Locking	24
Inside Light Delay	25
Bulb tester for check control	26
Independent electronic transmission conrtrol	27