This is how you swap your generator


Problems starting the engine? Does the car battery discharge very quickly even though it has only been replaced?

If your car won’t start or the battery warning light/charge indicator light comes on, this indicates a defective alternator.
The alternator, also known as a generator, converts the energy from the engine and uses it to charge the car’s battery.

If you experience the above problems with your vehicle, you should definitely take action.
First check whether the cables of the alternator are defective or other components.
You can simply swap out the cables. If the fault lies somewhere else, for example the controller, we recommend installing a new generator instead of repairing it.

To save costs, you can do the whole thing yourself. This means you don’t have to pay for the workshop employees’ working hours or expensive workshop products!

Do you feel ready to replace your defective alternator with a new one yourself? If not, please visit your trusted workshop and have your alternator replaced or repaired by a professional. So that you know how to change the alternator correctly, we explain step by step below how to remove the old alternator and how to install the new one again.

Ready? Well then get to the tool and replace the alternator!

Tools to change the alternator – you need this:

Gather the following tools before you begin the transition:

Although changing the alternator is not difficult in principle, it should not be carried out by laypeople and should only be carried out with the right tools!

Step-by-step instructions for changing a generator:

  • Open the bonnet and disconnect the battery

Since you are also working on the vehicle electronics when replacing the alternator, the battery must be disconnected first.
It is important that you solve the poles in the right order! First you disconnect the negative pole and then the positive pole.
Tip: Open the driver’s side window or keep the key outside of the car, as some vehicles lock themselves if the car battery is disconnected.

Tip: If you find that the V-belt is porous, it is best to replace it at the same time!

  • Disconnect electrical connections

    As already mentioned, the generator supplies power to the battery. Cables are of course required for this. Before you can remove the generator, you have to unplug the connectors that are attached to it. Some are screwed on. If that’s the case for you, you still have to unscrew them.

  • loosen the alternator

    Depending on the vehicle and model, the generator can be located in different places.
    In some cases, the paneling, the headlights or the radiator grille have to be removed in order to be able to reach the alternator easily.
    Tip: If you can’t get to the alternator well enough from above, you should have a lifting platform available!
    Before you can remove the alternator, you must first remove the V-belt from the pulley.
    To do this, slacken the V-belt with the appropriate wrench and secure the tensioning pulley with a suitable tool, such as a fixing mandrel or an Allen key of the right size. This will also hold the belt tensioner in its current position.
    In order to be able to take the defective alternator out of the car, you have to remove all the fastening screws.
    If other parts, such as hoses, are blocking the alternator, you should put them aside or remove them to make the change easier.

  • Remove defective alternator

    After all screws for attachment have been removed, you can now take the old alternator out of the vehicle so that the new one can be installed.

  • Insert new generator

    Before you install the new alternator, you should compare it visually with the old one to make sure that both are identical.
    Then you put the generator back in your vehicle so that it lies like the defective alternator and can be fastened again with the screws.
    A notice: The alternator must not wobble or loosen even when the engine is running!

  • Connection of the electrical lines

    In order for the battery to be recharged, all cables must of course be reconnected.
    All you have to do is reconnect the plugs to the new alternator.

  • Reconnect battery

    Next, reconnect the battery: reattach the cables to the car battery posts in the correct order.

  • Check alternator

    To avoid unnecessary damage, check again that nothing wobbles and that you don’t have to tighten any screws afterwards.
    To make sure that the new generator works again, you should check it again for unusual noises before the next trip, because an intact alternator should not make any noise!

  • carry out a test drive

    Finally, you take your car for a short test drive.
    This will help you determine if everything is stuck and working as it should.

How long does it take to change the alternator?

How long it takes to change the alternator depends on a number of things.
On the one hand, your previous knowledge and manual skills have something to do with it, but the time required to replace the alternator also depends on the vehicle model and where the alternator is located in the car.
Professionals and experienced screwdrivers can use the generator within 30 minutes exchange.
If you have little experience, you will need more time to change the alternator, you should plan at least an hour.

How much does an alternator change cost me?

The price for your new alternator can be between 100 euros and 1000 euros, depending on the dealer and car model.

You can find auto parts at ATP cheap alternators from top brand manufacturers such as Bosch, ATL, Valeo and many more.

If you include the cost of working in a specialist workshop, you pay Total costs within the framework of approx. 130 euros and 1260 euros.

Did this guide help you? Perhaps you have already changed your generator and have tips for other readers. Write us a comment!

Here you can find the replacement instructions for the alternator clearly as a PDF:


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