subject: Bypass Complex Car Elecronic Issues With A Digital Panel Meter [print this page] Modern car electronics are becoming more and more complex. This means that when something stops working, it is becoming much harder to find the root cause of the problem, using a digital volt meter can make the job easier.
Checking Fuses
The first thing to check is the fuses. Use the car's handbook to find the location of the fuse box, and the specific fuse for the item that is not working. Remove the fuse. If someone has an older car, they can probably see if it has blown. With some of the smaller plastic types used on European and Japanese cars, they may have to set the meter to continuity mode and check whether the fuses still work by touching the probes to each end of the fuses. If the fuse is blown, they can try replacing it. If it blows again they can use the digital panel meter to check for shorts to ground to see if that is the problem. If there are no shorts, then they can set the meter's mode to measure current and see if the device is trying to draw more current than the fuse for which it is rated.
Checking for Power
The next thing to check is that power is actually reaching the fuse and the item that is not working. To do this, set the meter's controls to allow them to measure DC volts. With most cars, the highest voltage they should get is around 15V, so if the digital meter requires set ranges, choose one that will not be overloaded by a 15V signal. Now the meter is set up. At this point the user can actually start checking the car for power. Before replacing the fuse, check both sides of the fuse's holder. One should have the same voltage as the car's battery and the other should show zero. If that is the case, it can now be replaced, and the user can verify whether they now have voltage on both sides.
Once the user has verified that they have voltage on both sides of the fuse's connection, they need to check for power at the part that is not working. If they have voltage there, then chances are the actual item has a problem. If there is no voltage at the item, there may be a cut or break in the wiring between the fuse and part, which would then need to be found and fixed. There may also be a relay, which is like an electronic switch, between the fuse and part which may be causing the problem. Normally, the best way to find any relays that may be in the circuit is to find a wiring diagram for the vehicle.
