How to Check Fuses In Your Car or Truck

How to test vehicle electrical fuses with a test light.

Using a test light(1) connected to a GOOD ground, probe both sides of the fuse. Key must be on.
It is a good idea to check all fuses in all fuse blocks when a blown fuse is suspected. Some of
todays vehicles use many fuses and several fuse blocks to power a particular circuit / system.

Watch Video

Example of Good and Blown Fuses

Fuse rating and color chart

The fuse is the most common method of an automotive wiring circuit protection. Whenever there
is an excessive amount of current flowing through a circuit the fusible element will melt and create
an open or incomplete circuit. Fuses are a one time protection device and must be replaced each
time the circuit is overloaded.

1-2-11
I have a pontiac grandam 2003 and it wont start we replaced battery,checked
starter,tryed w/booster cables still wont start not sure what it is ?

Comments

A battery can be so far gone that a jump will not help.
Check for power at the purple wire at the starter when
cranking. It should be hot. Is the theft or security light on?

10-13-11
i have an 04 grand am gt and some of the fuses in fuse box under hood have no
power such as ignition module. is this normal

That depends if you are checking the fuses with the key
in the on or off position. Some fuses will have power with
the key off, most with the key on, some only when a
certain circuit is being used- such as headlights. If the
car does not have any starting or running problems, I
would not worry about your findings.

1-3-12
where is the starter relay for a 2001 Monte Carlo?

1-5-12
I have a 1997 Oldsmobile Aurora the car drives normal until the check engine light comes
on and the car feels like something is stuck, the idle goes high and I try to step on the gas
it strains and looks as if it will over heat. Do u have a clue what could b the problem.

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How To Check Fuses