Beetle Wiring Basics Jeremy Goodspeed. This article was contributed to 1. Jeremy Goodspeed of Goodspeedmotoring. The vintage Volkswagen community thanks you The basic wiring of a VW Beetle is very similar to many other types of European cars. Like most cars, with age, time and exposure, resistance can build up in a wiring harness and render simple circuits useless. How To Install A Vw Bug Engine Diagram' title='How To Install A Vw Bug Engine Diagram' />Amsoil ZROD 20W50 Synthetic Motor Oil, QUART, ZRFQTEA is one of the finest engine oils you can use for our Flat Tappet aircooled VW engines. So with basic understanding of European wiring standards, many repair tasks can be tackled. From the addition of a simple accessory to a complete wiring harness overhaul, following some simple rules will make for a successful repair. First, we need to discuss a few basics regarding VW wiring. If you have spent any amount of time looking at a VW wiring schematic, you will notice that RED is used for constant power, meaning powered regardless of the ignition position, BLACK is switched power and BROWN is used for ground. The other colors will vary depending on the circuit but these three colors will cover most basic circuits. In addition to the color coding, a VW wiring schematic will have a number coding assigned to each terminal on a switch or other hardware component. These European terminal designations are also known as DIN standard and are used to determine a terminals use. P8210003.jpg' alt='How To Install A Vw Bug Engine Diagram' title='How To Install A Vw Bug Engine Diagram' />An air cooled VW engine rotates about 150 million times in 30 thousand miles. If thats too many for you, stop reading. If its not, keep reading. First, take a look at the Bosch Terminal Designations. These numbers are generally printed on the switch or other device for easy reference. As you work with DIN standard wiring, certain numbers will be seen more often than others. For example, a terminal designation of 3. While a terminal designation of 1. As you become more familiar with DIN pin designations, you should be able to figure out the purpose without looking at a wiring schematic. Now when you combine the colors with the pin designations, you will notice a pattern. Red wires go to pin 3. The next item you will notice on a VW wiring schematic is a number size assigned to every wire. The number wire size varies from 0. This refers to a European sizing that is measured in millimeter squared mm. European gauge wire is not easily obtained in America, so for replacement, it must be converted to AWG America Wire Gauge. The conversion from European wire size to AWG is not exact. Using a slightly larger wire size is good assure against resistance and heat. For example a 1. 0 mm wire should be replaced with a 1. AWG wire which is 1. European to AWG Wire Conversion Chart. AWG 0. 5. 1 mm1. Now that we have some wiring basics covered, the next task is to gather the proper supplies for a correct job. You may need some or all of the following Solid colored stranded wire, stranded tracer wire wire with a colored stripe, brass open barrel German electrical connectors with installation tool, junction connectors and PVC plastic sleeving. No one vendor supplies all of the listed items, so here is a list of vendors for your supply needs If your goal is to replace your entire wiring harness to factory specifications, you may decide a pre made replacement harness as a good option. These harnesses fit good, wire colors codes are accurate and can be installed in about a day. Many VW vendors sell these, so see if this option is for you. Following either the instructions or a factory wiring diagram makes for an easy installation. However, if your vehicle is right hand drive or your goal is something custom, altered or improved, a custom made harness may be your best choice. A custom made wiring harness will require much more time than a pre made harness. It also requires an excellent knowledge of wiring and is not for the beginner. The vehicle pictured in the article needed some mild, but necessary changes. Our goal was to make these changes without losing the original factory look, being careful to follow the original DIN color coding exactly. This becomes vital for future repairs, especially if the vehicle is sold. First, we needed to add grounds to all external light circuits. This is a very important step, as early VWs use a body ground for these circuits. As we restore our cars, the mill thickness of paint diminishes the ability for the circuit to use the body ground properly. This results in poor lighting performance or sometimes an intermittent flickering of the effected light. Bright and reliable lighting is a very important item. Newer VWs used ground wires instead of body grounds as this problem is prevalent. Installing Jacuzzi Tankless Hot Water Heater here. Second, was to improve the quality of the headlamp illumination by adding two 4. By adding a separate power lead for the headlamps and controlling them with a pair of 4. RPM. Understanding that relays are electrically controlled switches, we can use one relay to control both low beam bulbs and the other to control the hi beam bulbs. Another feature is with a single separate 8 AWG power supply run directly from the battery to the relays 3. DIN power pin, you can also add higher wattage headlamp bulbs without overloading the system. Furthermore, by separating the power used for the headlamps from the headlamp switch, we were able to eliminate most of the amperage load and prolong the life of the switch. This info will describe the typical installation of headlamp relays. For installation in a VW Beetle, please note the following. Pin 8. 6 is easily drawn from the stock hi low headlamp relay. Simply run the yellow and white wires from the hi low relay to each 8. Pin 8. 7 of the relays then is connected to the fuse box like factory. Please note that pin 8. Why is a ground not PIN 3. Relays are used in many configurations, and pin 8. This depends as to the purpose of the relay. In this case, it is used as a ground. As you begin building your wiring harness, it is a good plan to have all yourhardware items, such as your fuse box, wiper assembly, switches and relays installed in the vehicle. This installation will aid in determining the length of wiring needed to complete a circuit. To help with the location of those numbered pins, take a digital photo of each item before installation into the vehicle. Simply refer to these photos for an easy reference. Many times these numbers are small and difficult to view from inside the dash area. Building and installing a wiring loom can seem overwhelming at first. However, as you simply separate each wiring loom section it becomes easier to manage. The VW beetle has a main loom, left and right front lighting loom, and two short and simple tail lamp looms. Beyond these main looms, are short groups of wires between switches and relays. The main loom that spans between the dash and the rear of the car, have only 1. I added two additional wires to power the headlamp relays and the electric fuel pump to this project. To begin building the harness, make sure the lengths of wire is sufficient for the run. The main loom needs to be built outside of the vehicle. Take careful measurements so your loom is the correct length. I generally leave the wiring longer than needed so we can trim the length once the loom is installed in the vehicle. Once the length is determined, group the proper wires into a single bundle. Generally using a quality electrical tape every 1. Once the wires are loomed into a proper group, slip the PVC tubing over the group. Next, install the main loom into the vehicle and adjust until it is located properly. Finally, we can trim the wires to proper length. Make sure to leave the wires long enough for maintenance. Then, install the brass open barrel electrical connectors. These connectors are identical to the factory connectors. Using the proper crimping tool assures a good connection.