Battery self-discharge

If you suspect a battery leak, check the on-board network as follows.

Attention! The battery must be fully charged to carry out the test.

Turn off all power consumers, disconnect the connector from the clock, close the doors.

Set the ammeter to the maximum measuring range. Disconnect wire "masses" from the battery. Connect one ammeter wire ("-") to the negative terminal of the battery, and the other ("+") - to the disconnected wire "masses".

Attention! The check can also be carried out using a test lamp. If the lamp does not light up, check with an ammeter.

Switch the measurement ranges of the ammeter up to milliamps until the device starts to give readings (permissible current - 2-3 mA).

Interrupt various electrical circuits in succession by removing the appropriate fuses. If, when the next circuit is interrupted, the ammeter needle returns to zero, the malfunction should be looked for here. The source of the malfunction can be rusted and dirty contacts, frayed wires, internal short circuits.

If no defect is found in circuits protected by fuses, the wires from unprotected units should be disconnected in sequence (e.g. generator, ignition system).


Connect wire "masses" to the battery.

Attention! If self-discharge of the battery is observed in a car manufactured before May 1989 with a central injection system, the reason may be in a defective oil pressure sensor: its contact sticks, which prevents the fuel pump from turning off when the engine is turned off. This leaves the pump circuit energized and the pump runs continuously, draining the battery. In some cases, this can lead to burnout of the wire or control relay. To prevent or fix this defect, do the following:

• Disconnect the connector from the oil pressure sensor.
• Pull off the rubber tip.
• Of the three wires coming from the sensor, bite the red and red-blue wires with side cutters and insulate.
• Pull on the rubber tip and connect the connector.
• Check the operation of the oil pressure sensor: with the ignition on, the emergency oil pressure lamp on the instrument panel should light up and go out after starting the engine.
• Check the operation of the fuel pump relay: after turning on the ignition, the fuel pump should turn on for 1-2 seconds, and then turn off.