- reliability of fastening of power wires to the battery terminals (make sure they are clean and secure);
- electrolyte density in the battery (if the density is low, charge the battery);
- electrical wiring of the generator and the reliability of its fastening;
- condition and tension of the alternator drive belt;
- tightening the alternator mounting bolt;
- noises heard from the generator after starting the engine.
With the ignition off, check the voltage at the battery terminals with a voltmeter by connecting it to the terminal «IN» generator. The voltage should be around 12V.
Attention! When checking the generator, it is not allowed to connect to «weight» conclusion «L» with the engine running, or start the engine with the wires disconnected from the terminals «L» And «R».
Pic. 13.4. Wiring diagrams for checking the generator (A) and voltage regulator (IN): 1 - voltmeter; 2 - relay for turning on the control lamp for charging the battery; 3 – a control lamp of accumulator battery charging; 4 - ignition switch; 5 - ammeter
To check the charging system, assemble the circuit in accordance with fig. 13.4. With the ignition off, check the voltage between «weight» and conclusion «L» generator. If the voltmeter does not show voltage, then the generator is faulty. Turn the key in the ignition switch to position «ON» and check the voltage. If the voltmeter does not show voltage, then the generator or wires are faulty. If the voltage is close to the battery voltage (12 V), connect the output «F» with the alternator rear bracket and check the voltage. If the voltage shown by the voltmeter is less than 12 V, the voltage regulator is faulty. To check the voltage of the regulator without load, make sure that the battery is fully charged, connect the ammeter and voltmeter in accordance with the diagram in fig. 13.4. With the ignition off, the voltage shown by the voltmeter should be zero.
Turn on the ignition, while the voltmeter reading should be 1-3 V below the voltage at the battery terminals. If the voltmeter reading is equal to the voltage at the battery terminals, then the alternator is faulty. Close the terminals of the ammeter with a jumper, start the engine and remove the jumper.
Attention! Before starting the engine, make sure that the ammeter is not connected to the starter power circuit.
Increase the engine speed to 2500 min-1 and read the ammeter and voltmeter. The current shown by the ammeter should be equal to 5 A, the voltage - (14,7±0,3) IN (at 20°С).
Pic. 13.5. Electrical circuit for checking the voltage and current generated by the generator: 1 - terminal «L»; 2 - terminal «IN»
To check the current and voltage generated by the generator, disconnect the wire from the negative terminal of the battery and connect an ammeter and voltmeter in accordance with the diagram shown in fig. 13.5.
Connect the cable to the negative battery terminal, start the engine and turn on the headlights. Gradually increase the engine speed and watch the voltmeter reading. The charging system is OK if the voltage exceeds the battery voltage and the ammeter shows current flowing.