Alternators & Starters - Choosing the Right One

Vehicle platforms having overlaps on year of manufacturer are increasingly common.

This leads to changes and variations of the models and choices of parts fitted to the vehicle.

A common misconception is that ‘they look the same so it will be fine’, but this is not always the case. Yes, you will find there are many applications which have choice between starter motors and Aalternators and the difference can be as simple as amperage (alternator) or kW (starter motor) but many other starter motors or alternators can have significant differences such as;
    • Starter Motors: Pinion position i.e. the throw or home location of the pinion is different
    • Alternators: Regulator termination i.e. controlled by ECU or voltage supply

Fitting an incompatible part can cause damage to the alternator and/or the vehicle.
If the incorrect starter motor is fitted with the pinion in the wrong position, it can cause damage to both the flywheel/ring gear and the starter motor. If the material that the pinion is made from is softer the flywheel, you will usually experience damage to the pinion teeth before any subsequent damage to the vehicle.

If you fit an alternator with the incorrect termination, this can have a significant impact on both the vehicle and the alternator. A recent example of this was on a Volvo XC90. The vehicle has two options of alternators. One works on a conventional warning light circuit where the other works with a computer controlled signal. As both circuits functions differently, they are not compatible with each other. In this instance the customer chose to supply one alternator without checking the difference or original equipment numbers from the original alternator. They supplied the conventional alternator option, which functioned with a 12v battery warning light circuit. As the fitment of the alternator and the connections were the same, the mechanic had no reason to question the Alternator they had been supplied with. The mechanic has since reported that damaged to the vehicles CEM has occurred and billed the motor factor as it was their error for supplying the incorrect alternator.

In any instances where there is a choice in parts for one application, it is critical to obtain original equipment numbers. Aided with our predictive text cross reference on our industry leading website you can rest assure that you will be fitting the correct part the first time round without the risk of causing damage to the vehicle.

If you have any concerns with any Autoelectro product do not hesitate to contact us and our dedicated and trained technical advisors will assist you with any enquiry.