the Laying on of Hands

Whether you're planning a major wring job on a custom car or just need to fix some little issue that the PO left behind, one of the first things you're going to need is a bit of research. Even on a Vintage car that has been well cared for, there's bound to be some wiring that was "rigged" to get the owner going in a tight situation. A modern car can be a whole other ball of wax.

So- now the pressure is on you, there's a problem that needs fixing, and most likely there's some kind of deadline looming- am I right? Even the strangest problems usually have a simple solution- we'll stay away from computers a drive ability issues for now. Take a breather and get a fresh look at the problem. NO adult beverages until you at least have a plan of attack!

If this is you first electrical experience with the vehicle, take a look at the parts related to your issue- a turn signal bulb COULD be in the socket the wrong way for instance. Start with the very basics- unless you see visible damage to a component, think about battery voltage (you should have a cheap VOM, NO test lights!) Pretty much any car needs a solid 12 volts for anything to work correctly. Measure this at the battery with the car off and then running- minimum 12 volts and maybe 13 plus when running ?

Every electrical part needs a ground as well- this is the most common cause of gremlins due to corrosion or careless re-assembly of various parts. It's kind of the automotive equivalent of laying on of hands- run your hands along the harness for a particular part, looking for something out of place, and follow back to the nearest junction or ground connection.

Example- a nice modified Mazda RX2 that we worked on seemed to crank OK but had a really hard time starting, poor ignition spark. OK- rotary cars can be hard to start, but it wasn't until the choke cable burst into flames that anyone thought to check the engine ground ! There was enough of a ground through the cable's metallic sheathing to crank it (for a while) but the voltage drop kept the ignition from firing. LESSON- measure the voltage right at the suspect part (ignition in this case)  Whoever did the very nice restoration on this car never replaced the engine ground strap. You know you need one of these, right?