The VW Passat is a four-door sedan that comes with a manual or automatic transmission. If your VW Passat will not start properly, it might be a problem with the starter. The starter on your Passat sends an electrical signal from the battery to the engine when the key is engaged in the ignition. You can test the starter with minimal automotive knowledge and little hassle.
Park your VW Passat on a flat surface. Engage the emergency brake to secure the car from rolling. Make a note of the security code for your Passat's radio. You can find this in the owner's manual.
Open the bonnet and use a wrench to disconnect the black cable from the battery on the right side of the engine. Go under the car and check for the engine shield. Use a wrench to remove the shield if your car has one (some models do not use an engine shield).
Pull the shield out from under the car and locate the starter. The starter is located on the right side of the engine's bottom. Disconnect the red cable from the car battery, then connect the red and black leads from your voltmeter to the starter's red and black wires going to the battery.
Look at the instrument display for a reading. If you do not get a 12-volt reading, you either need to replace the starter or the battery. Test the battery terminals with your voltmeter and replace the battery if needed.