Check of the relay of the fuel pump of the BMW 5 E39
Procedure:
1. Fuel pump relay (2) is located at the right side of the trunk behind the cladding on the battery. See the accompanying illustration. It supplies electric current fuel pump. By means of the safety switch, it stops the flow of fuel, if when the ignition is not received pulses of the engine speed. If checking the injection system must run the fuel pump without starting the engine, disconnect the relay and connect a short wire terminals 30 and 87b (Diesel: terminal 87). Wire diameter 1.5 mm.
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Note: To check the fuel pump relay battery must be charged.
2. Check the fuel injection system fuse. Fuse is shown on the cover of the fuse box.
3. Disconnect the fuel pump relay.
4. Connect a short wire terminals 30 and 87b (Diesel: terminal 87). See the accompanying illustration. Not to damage the sensitive relay contacts. If the pump operates, replace the relay. If the pump does not work, check the wires going to the relay and the fuel pump. If necessary, replace the cable.
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5. Check the relay, fuel pump.
Relay:
For the electric current supply to some components of the vehicle electrical accessories used relay. Infringement of functioning of the relay leads to the failure of a component served by it.

In the event of a suspected malfunction of any of the relay, it must be removed and subjected to a diagnostic check in dealer branch of the company or a specialized repair shop. Replacement of the failed relay is made in gathering.
Check of the relay:
Many circuits are composed of relays. If the user manually turns on the relay is ordered to bring the food to the consumer. You can bring food to the consumer directly from the battery. With significant consumed currents in the circuit, the relay, so as not to overload the circuit breaker. Along with the relay of inclusion are also functional relay, eg relay wiper-washer of a windscreen.
Checking switching relays:

When the corresponding user a signal to the relay. At the same time the electric current control, acting on the electromagnetic coil, closes the operating current circuit, providing power consumer.

The easiest way to test the functionality of the relay, replace it with another, serviceable. For example, enter the service station. In the absence of spare relay it is recommended to check the following. The following terminal designations may differ from those available.
Check:
1. Remove the relay holder.
2. Turn on the ignition and relevant switch.
3. Use the device to control the voltage check if the voltage at terminal 30 (+) relay holder. To do this, connect the unit to the ground (-), and the other device tip gently insert into the terminal device 30. If the LED lights up, the voltage is. If the device shows no voltage, check the circuit for an open on the way from the positive pole (+) of the battery to the terminal 30.
4. Prepare a jumper from the insulated wire with stripped ends.
5. Connect a jumper from terminal 30 in the relay holder (+ battery, always energizes) with the release of NO contact relays (terminal 37). Thus, simulated work-good relay. Where are the terminals in the relay carrier is indicated on the relay.
6. If the jumper is enabled user is working, it is possible to conclude that the fault relay.
7. If the user does not operate, determine whether the compound in order to mass consumer. Then, check the connection from the terminal 87 to the user. At breakage Repair.
8. If necessary, insert a new relay.