Fuses and Codes
by Pat Goss
Cars have changed; the tools we use to fix them have changed. Hand tools like wrenches and screwdrivers are being replaced by code scanners or code readers used to troublshoot and diagnose problems. These scanners used to be very expensive, and out of the price range of the average consumer. But as technology has progressed, prices have dropped. Pat has some affordable options.
This particular one is from Actron, and of course there are several different makes on the market. What this does is just read computer fault codes and just gives you the number. Well, you can step up to something that gives you more scanning capabilities, and scanning capabilities mean that you can look at some of the signals from the various sensors. Or top of the line which will give you part of the data stream. It will give you information about the different systems on the car. It can even read ABS. These things used to be in the thousands of dollars; now they're very affordable.
But when you start doing these you're going to be looking at codes, that's the one thing everybody's interested in, and codes can get you into a lot of trouble. There's a bunch of sensors under the hood and underneath the car, and there are actuators, like variable valve timing actuators, or the cam sensor, or the mass air flow sensor. All of these things have codes related to them. So you read the code and it says something about the cam sensor. Well, that doesn't necessarily mean the cam sensor is bad, could be the wire leading to it, or any of a dozen other things. So what do you do? Well, you need a manual that does two things. First it has to give you a description, and the way the various sensors work so that you understand them, and it has to give you the code diagnostic tree. For each code number there's a matching tree that walks you through these "Go/No Go" steps to get you to the real answer. If you start replacing parts you're going to waste money.
All right, you'll also want to have some form of digital voltometer. They are thousands of them out there, any price point that you want. Just pick the features that you need and you want and you're good to go there. Now, there's something that can save you a lot of time. Pretty clever piece, it's called a Fuse Buddy. Now, you take the fuse out of the affected circuit, you plug this in and it tells you how much electricity is flowing through that circuit. Now that can help you determine if you have a dead short or if you have excessive current flow through shorted windings inside a solenoid or a relay or something like that. Very inexpensive, very handy to have.