Being able to change your cars blown fuses yourself is a great idea, since it can save you money and time, and it could even help you in a tricky breakdown situation. A car uses electricity for many of its functions, and a blown fuse could mean that your car radio no longer works, or worse, that you find yourself without lights on a dark night.
The fuse box is often located in or around the instrument panel near the dashboard of the car and most modern cars have as many as 40 fuses. There is sometimes a second fuse box under the bonnet, usually near the battery. Classic cars tend to have less circuits (no electric windows, sat nav ect) so have less fuses and are usually in the engine bay. The problem with this is that many circuits share the same fuse so blowing one fuse you can loose a number of circuits. Have a look through your owner’s manual and familiarise yourself with your vehicles particular fuse box or boxes and grouping.
Check how many, if any, spare fuses came with your car by checking the fuse box for spares and always keep some extras in the glovebox. When buying spare fuses, note that modern fuses are colour coded by amp rating and can be bought from any auto shop and even some petrol stations.
Replacing A Fuse
Before you replace a fuse yourself, please note that you can never replace a blown fuse with a higher-amp fuse. Use a new fuse with the correct and specified amp rating. In an emergency it is acceptable to install a smaller amp fuse, for a short period only but should be replaced with the correct amp fuse as soon as possible as there is always the chance that this fuse will blow as it will be working closer to the current in the circuit.
Check with the owner’s manual to pinpoint the location of the fuse you’re looking for, then remove the fuse box cover and look for a locator sticker. This works for modern cars where each circuit has its own fuse (so if your horn is not working then there will be a fuse for horn)
Remove the fuse that’s labelled for the device that’s not working. Use a pair of needle-nose pliers if you do not have a fuse puller. For a classic car which only has 3 or 4 fuses it is usually easier just to check all the fuses.
Check The Fuse
Too see if the fuse is burned out and really is at fault here, hold it up to the light and see if there is a fine wire connecting the two sides of the fuse. If there is a fine wire, then the fuse is still good. If you have a multi-meter you can use it to double check the continuity of the fuse. Return the fuse to its former position now and consider another reason for your breakdown or the source of your car troubles..
If a section of the fine wire has been burnt or is broken or missing, then you need to replace it. Don't throw away the burnt out fuse but keep it to one side to remide you to buy some new ones. Replace it with a new fuse of the same colour, size and ampage.
If this new fuse burns out very soon after you have installed it then you are going to have to investigate the problem as you either have a short circuit or one of the components in the circuit is taking too much current.
On the MGB the fuse box is located in the engine bay on the right hand side and only has a few fuses fitted to cover all the circuits
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