[Shop-talk] Finding a Blown Fuse (Automotive)

[Eric Russell]

> How are you verifying that the fuses are good? If you are just looking at
them, they may still be bad or making a poor connection. Use a volt meter &
measure voltage on both ends of the fuses to verify them.

Initially, I just pulled the likely fuses for a visual inspection. When
that came up empty, I used my Horrible Fright ohm meter to confirm
continuity between the two terminals of the fuses. I've swapped in known
good fuses to no avail. I have checked (at least visually) every fuse I can
locate. I am 99% certain there must be another fuse somewhere.  If you have
experience working on motorhomes you'll know anything is possible...

Me no see video - link missing?

> I can walk you through the troubleshooting if you need help.

Yes, please - t y p e    s l o w l y . . .

EjR

On Wed, Nov 10, 2021 at 8:01 PM Pat Horne <patintexas at icloud.com> wrote:

> Here's a video of using the tool. Since you have only one wire, the other
> clip should go to groud.
>
> Peace,
>
> Pat
> On 11/10/2021 6:15 PM, Eric Russell wrote:
>
> Oh wise & beneficent Shop Talkers - I've run into a situation that has me
> stymied. I need help locating a blown fuse in a motorhome.
>
> We recently bought a new (to us) motorhome. When installing the signal
> booster for a TPMS (Tire Pressure Monitoring System) I accidentally shorted
> a 12V wire in the cargo bay lights. There was a small spark (followed by a
> few swear words). I then went on a hunt for the blown fuse. There are three
> fuse panels in this motorhome. Two in the Ford chassis (F-53) - one under
> the hood and the other inside near the parking brake - plus one in the
> motorhome's 120V - 12V power converter. I could not find a blown fuse
> anywhere.
>
> I contacted the manufacturer (Thor) who has actually been quite responsive
> & has tried to help. After asking for my vehicle's VIN they emailed me some
> schematics (not actual wire diagrams but more a map showing the general
> location of outlets, switches, etc with indications of which circuit they
> belong to). There are two schematics that appear to apply to my motorhome -
> one indicates the cargo lights are connected to the Ford panel by the
> parking brake, another indicates they are in circuit #6 of the converter's
> 12V panel. Neither of those fuses are blown. While there I checked all the
> fuses I could locate - none were blown. I've also signed up to a couple of
> motorhome forums but have not been able to find an answer there.
>
> Finally - my plea for help - is there any device one can use to trace
> where a circuit originates? I've seen an electrician use a device to find
> out what outlet goes to which breaker in our house.
>
> I've followed the hot wire from the cargo bay light back to where it
> enters a wire harness along the motorhome's frame rail. I'm loath to rip
> open the wire harness trying to chase the wire further upstream. As far as
> I can tell there is nothing else in this circuit - everything else is
> working properly. Of course I can live without cargo bay lights but it
> bothers my OCD to have it not working (when I know it did before my screw
> up).
>
> --
> Eric Russell
> Mebane, NC
>
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-- 
Eric Russell
Mebane, NC
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