Where is the main relay located in an old Audi A4?

[AnnieMarie]

In the old Audi A4, the main relay is located on the left side of the drainage trough, next to the engine control unit. Below is a detailed introduction about it: 1. Introduction 1: The starter relay is a specialized component for compressor startup using single-phase asynchronous motors. 2. Introduction 2: The starter relay is a separate component whose function is to connect and disconnect the attraction coil and holding coil circuits. 3. Introduction 3: The purpose of the starter relay is to assist the motor in starting. After the startup is completed, it automatically disconnects the auxiliary winding to prevent burning out the auxiliary winding coil. When the motor's running winding is powered and transitions to normal operation, the starter relay cuts off the power supply to the startup winding.

[VanClara]

I've tinkered with my friend's old Audi A4 before, and the main relay is located in the engine bay. Just remove the black cover (fuse box) in front of the driver's side, and you'll find a bunch of small square components inside—those are the relays. Look for the one labeled 'J271' or marked with a relay symbol, usually positioned near the center. For pre-2007 B6/B7 models, it's typically located here. By the way, plastic parts on older cars tend to get brittle, so avoid using excessive force when removing the cover. If the relay pins have green oxidation, lightly sanding them before reinserting might bring it back to life.

[LeColeman]

Last month, I just helped a colleague fix their 2005 A4. The main relay is located on the left side of the dashboard, and you'll need to crouch down and look under the steering wheel. Remove the long cover with the triangular warning symbol, and you'll see seven or eight black relays inserted vertically inside. The key is to find the one numbered 271, as some models might label it J682. A word of caution: always take a photo with your phone to remember the position before pulling it out. Plugging it into the wrong slot can instantly prevent the car from starting. Remember to wear rubber gloves throughout the removal and installation process to prevent static electricity—older car electronics are quite delicate.

[RileyMarie]

The old A4 has two possible locations for the main relay. For the 2001-2005 models, it's located in the engine compartment fuse box, squeezed next to the wiper motor. The 2006-2008 models moved it to the fuse box above the driver's knee area. First, check the 10th digit of the VIN: B indicates 2003-2004 models (engine compartment), while C means 2005-2008 models (dashboard). Remember to remove the fuse box cover – the relay position is marked with a circuit diagram and a magnifying glass icon. Always disconnect the negative battery terminal before working – last time I forgot this step and locked the radio.