Checking the relay (BMW 3 Series E30)

The easiest way to check a relay is to replace it with a known good relay. As a rule, relays are checked at a service station in this way. However, since there is not always a stock of all types of relays at home, the following technology for checking the so-called working relays is recommended, which, among other things, are used to turn on fog lights and main lights.



The main part of the relay is located in the fuse box on the left side of the engine compartment.

The box cover shows a diagram of the relay location.

• K1 - Additional fan relay, stage 1
• K2 - Fanfare relay
• KZ - High beam relay
• K4 - Relay for low beam, rear headlights
• K5 — Relay for heated seats, sliding roof panel, electric window lifters
• K6 - Additional fan relay, stage 2.
• K7 — Heater fan relay, electric drive of outside mirror
• K8 - Fog light relay
• K9 - Rear fog light relay (France. Switzerland)
• K10 — Relay for the control unit for intensive headlight cleaning

Remove the relay from the socket.

First, use a voltage tester to make sure there is voltage at terminal 30 of the relay block. To do this, connect the tester to ground and insert the other end into the terminal 30 socket. If the tester's LED lights up, voltage is present. If there is no voltage, find the open circuit from the positive pole of the battery to terminal 30 using the electrical diagram.



Make a jumper from a piece of wire, stripping its ends.

Connect this jumper to terminal 30 (+) of the battery (the voltage is present constantly) with terminal 87 of the relay block. The location of the relay contacts is indicated on the relay and on its block.

If, for example, the high beam headlights light up when the jumper is inserted, then the corresponding relay is defective.

If the high beam headlights do not light, use the electrical diagram to find and repair the open circuit from terminal 87 to the main headlights.

If necessary, install a new relay.

[The original source of the article is on the website: BMWman]