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Alternator relay: replacement and selection

When and why it is necessary to replace alternator voltage regulator

Manufacturers do not set terms of scheduled replacement for this component. A new element is needed in case of breakage or shorted contacts. And if the component is combined with alternator brushes, then it should be replaced at their wear-out.

Closure of contacts occurs mostly due to oxidation at moisture ingress, and open circuit can be caused by failures in the car electric system. First of all, wear-out of the alternator brushes is connected with their abrasion which leads to clogging of gaps between them with abrasive wear debris.

Defectiveness of the alternator voltage regulator can be indicated by the fact that the corresponding indicator lamp on the instrument panel doesn’t go on at ignition turning on. Also breakage is pointed out by the battery indicator, which doesn’t go on after engine start. A broken down part stops to adjust intensity of current coming from the alternator. Due to this, the battery can be charged insufficiently or excessively. Troubles with engine start quite often occur at insufficient charge. Sometimes it is impossible to start the car at all. Electrolyte boils out at excessive battery charge. You can learn about this, noticing the white deposit on the battery and near it. If the voltage regulator combined with brushes is broken down, then, in most cases, there will be no electric power in the car.

In order to replace the alternator relay, you need to demount the alternator and, possibly, a few other parts complicating access to the unit. It is necessary to perform this job in accordance with the instruction noted in the car technical documentation.

How to select alternator relay

These parts can be combined with the alternator brushes or can be separate components. The most common regulators are of the first type, however, the components without brushes are notable for a longer operational lifetime.

In order to make the part serve faultlessly during a long time, purchase it from a proven manufacturer. For instance, high-quality alternator voltage regulators are presented in the assortment of HELLA, VEMO, BOSCH.

During component selection be guided by the brand, model, production year of your car. Also consider the type and power of the alternator, working voltage of the relay. Moreover, the components can differ by the fastening type.