No power to my fuses

[lathe11]

Started my coach to bring it in for tires, no backup camera, ok fix it when I get home, Well, now the problem. Pulled the fuse panel found the fuse and it was good but no power to it, tried the fog fans, same thing driving lights you got it. All the fuse are good but not getting power to this same row, where do I look next to find the feed to the fuse block? Swapped the relays, checked the fuses at the batteries all check out fine , I am stumped, any help would be appreciated! Oh, coachman sportcoach,DP, 380.

[Sprig]

lathe11 wrote:
...visual inspection will not tell you anything!...

Fuses, for as long as I am aware, have been designed to be visually inspected for failure ... if it is black ... it's life is very much likely exterminated.

lathe11 wrote:
I see a lot of talk about pulling the fuses and looking vs testing both sides. SO after you look at them and determine they are good and the unit your trying to power up still does not work now what do ...

Well, unlike you, in the first place I don't get into some kind of childish hissy fit over the issue.

In the EXTREMELY rare situation where a fuse looks visually good, but seems to me to possibly be the culprit, I simply pull another fuse on the block of the same rating and swap the fuses for re-insertion; I do this for the reset-able circuit breakers also.

...and, btw ... if you have any simple knowledge about your fuse system ... you only need to EVER test the one side (testing fuses) ... if you have a clue ...

but ... but ... but ... !

Yep, that next question should never be asked.

[tropical36]

lathe11 wrote:
Thanks all, yes I have power to the panel, it is the two row of fuses that are energized by the ignition. I see the three big relays and have interchanged them and got nothing, there are two rows of relays at the bottom of the panel but none are labeled and there is no diagram. I believe that is where my problem lies ,but how do I check the relays??

There should be power on one side of the relay contacts and once the coil closes them, there should be power on the other side of the contacts. Ignition switch on should produce power to one side of the relay coil and if it does not, run a 12vdc jumper to the coil's hot side and see what happens for beginners. Also check for an established ground on the other side of the coil and keeping in mind that some systems will actually switch the ground return, like a brake switch or horn button does. Some of these relays may have a socket that's soldered on the PC bd, which makes it tough and in which case you can start by unplugging the relay and checking for these voltages there.

[lathe11]

I see a lot of talk about pulling the fuses and looking vs testing both sides. SO after you look at them and determine they are good and the unit your trying to power up still does not work now what do you do with your visual inspection? Like I said and others noted, check both sides of the fuse, if no power, track back to a fuse that feeds the panel that is out and check both sides, visual inspection will not tell you anything! Just my opinion, thanks again to all!!

[enblethen]

I guess I need to add this style of circuit breakers to the cartridge style (Sprig's first photo is what is considered cartridge) and Maxi fuse list that nee to be checked with Ohm meter.

[Sprig]

Take me about 10 minutes to pull and visually inspect every fuse in my main panel if there was no fuse chart.

[Sprig]

Due to different manufactures, and replacement parts over time, I never noticed that the mini-fuses had terminals on the top of the fuse.

Thanks for THAT info!

But, even though good info, why would I grab a meter or test light when something obvious doesn't work?

I just look up the fuse chart and match it to what doesn't work and pull the fuse to see if it is black; pretty simple.

Last fuse I had to chase, did not have terminals ... I had to visually inspect it.

I'll have the fuse image here or/on a link as soon as I upload and edit this post.





OK, I noticed that the fuses CAN be probed on both sides! So, I learned something... I learned how to waste my time.

The last fuse I had blow is in the top photo, and it can not be probed. I found out it was bad by looking on the fuse panel that described the item that no longer worked.

BLACK.

Second photo shows (at the bottom) two self reset-able circuit breakers (that are also labeled (and are also not testable from the top)).

For whatever reason, some peeps on here seem to want to throw my body into their backyard grave simply because they don't agree with my simple electrical advice.

Enjoy!

[FIRE_UP]

enblethen wrote:
Some of the new Maxi and cartridges fuse do not have test points. They need to be removed and tested with an Ohm meter.

Roger that Sir, learn something every day.
Scott

[enblethen]

Some of the new Maxi and cartridges fuse do not have test points. They need to be removed and tested with an Ohm meter.

[FIRE_UP]

Sprig wrote:

FIRE UP wrote:
...Many, many technicians will tell you that an "appearance" of a fuse is not a forgone conclusion that a fuse in intact...

Well, it is not PHYSICALLY possible to "put test leads" to EITHER side of the fuse with the new fuses on autos.

Seems a whole lot easier to just put an eyeball to it.

Well Mr Sprig,
I'm not sure of what type of fuses you've had to deal with but, ALL of the fuses I've dealt with have the capability of being tested with a meter or, a test light, while in their sockets. The AGC, ATC and "Mini" ATC ones all can be tested. Yep, sure it's a whole lot easier to "eyeball" them if and when, they're out of the socket to see if there's any defect or damage. But, it's important to see if continuity of power is there while they're in place. In the picture you'll see the contact points that you can put a meter on, on both sizes of the present day fuses.
Now, I don't deal with this stuff every day but, maybe the 2013 and later has fuses that are not "testable" while in place, I have no idea. But, the older ones, yep, they're testable while in place.
Scott

[Sprig]

FIRE UP wrote:
...Many, many technicians will tell you that an "appearance" of a fuse is not a forgone conclusion that a fuse in intact...

Well, it is not PHYSICALLY possible to "put test leads" to EITHER side of the fuse with the new fuses on autos.

Seems a whole lot easier to just put an eyeball to it.

[enblethen]

There are times where the fuse link becomes detached to the fuse connector. It doesn't always arc and burn.

[Sprig]

enblethen wrote:
...Looking at a fuse doesn't always work...

I've never seen a black and charred fuse with no longer any existing conductive material between the contacts to ever work again.

[FIRE_UP]

enblethen wrote:
Sprig ask how to test fuses.
Looking at a fuse doesn't always work.
I believe the OP found his main fuse that powered his two rows of fuses.

Absolutely correct! Many, many technicians will tell you that an "appearance" of a fuse is not a forgone conclusion that a fuse in intact. I've only seen it once myself but, it does exist. Yes, about 99.999% of them actually "blow" and show a burnt section of the link inside the fuse so, the appearance does give those away. So, if in doubt, DO CHECK BOTH SIDES OF THE FUSE IN QUESTION. At least you'll definitely rule that out.
Scott

[enblethen]

Sprig ask how to test fuses.
Looking at a fuse doesn't always work.
I believe the OP found his main fuse that powered his two rows of fuses.