Step by step guide on how to test and repair an automotive fuse problem, this
information pertains to all cars.
Difficulty Scale: 2 of 10
Start with the car on level ground, engine off with the emergency brake
- Most fuses are located in a power distribution
center (pdc) located under the hood or under the dash.
Step 2 - Identify the accessory fuse location
by consulting identification information found in the fuse panel lid, owners manual
or repair manual
Power Distribution Center
Most electrical components are supplied with voltage and are protected though the
pdc. The control relay and micro relay are used as a high amperage switch for devices
that require high amounts of amperage for an extended amount of time. The fuse or
fusible link supply voltage to sub electrical systems.
Step 3 - There are two ways to check the operation
of a fuse, first, simply remove the fuse and check for breakage of the internal
fuse circuit, though this can be time consuming.
Fuse Identification - Power Distribution Center
Step 4 - An easier process is to use a
to test fuses while still installed and in use, this test will confirm
and power through and at the fuse.
Step 5 - After properly grounding the test light
or voltmeter lead, turn the ignition key to the "ON" position without
starting the engine, gently touch the
probe to the two terminals of the fuse, if working properly the fuse will illuminate
the light at either terminal.
Step 6 - If a failed fuse is suspect, remove the
fuse for visual confirmation of the failure.
Step 7 - If a new fuse blows as soon as its replaced
it means that a wire or connection in that circuit is shorted to ground, this condition
could be internal as well, such as a burned out window motor. To repair such issues
investigation and troubleshooting using a wiring diagram and component locator is
necessary, first, remove or unplug each accessory in that fuse circuit. A wiring
diagram is necessary and obtainable at
Step 8 - If no power is detected at the fuse or panel
(either side of the fuse) use a wiring schematic to trace the power source, usually
a main power relay, maxi-fuse or fusible link has failed.
Electrical fuses protect vulnerable electrical circuits and components from burnt
wiring and fire. Fuse panels or owner manuals are labeled with specific amperage
ratings and circuit information.
- Replace failed fuses with proper amp rating; not doing so can result in
electrical system damage.
- Wrong amperage fuse causing wiring or component damage.
- Fuses can cause intermittent open circuits by becoming loose or corroded
in the fuse holder, make sure fuse is held securely, and free of dirt and
Article first published 2016-02-04