Electrical problems

[fdhoward]

Keystone Outback

Blowing 15 amp fuse in zone 2. When I put in new fuse it sparks and blows. Fan and lights don’t work on range and exhaust hood. Also refrigerator quit working. Any ideas. Checked everything on front of trailer and it all seems ok from tongue. Haven’t taken the bottom off yet. Wanted to see it anyone had suggestions before going to that step.

[sahively]

Wow, first are the fridge, range, and exhaust all in this zone 2? By quit working, do you mean they don't work because the fuse blew and they have no power or because they quit working and we're dealing with unrelated issues?

[chuckster57]

Welcome to the forum

Zone 2?

Do you mean fuse #2?

You have a dead short in that circuit. Do you have a Volt/Ohm meter and know how to use it?

[fdhoward]

Not sure about why things aren’t working. Can’t put a fuse in, it blows instantly. Yes I have a volt meter but not sure where to start. Checked all connection in electrical connection box on the tongue that connects to the truck pigtail. Can’t find anything there.

[flybouy]

Originally Posted by fdhoward

Not sure about why things aren’t working. Can’t put a fuse in, it blows instantly. Yes I have a volt meter but not sure where to start. Checked all connection in electrical connection box on the tongue that connects to the truck pigtail. Can’t find anything there.

I would begin by identifying every device on that #2 fuse. You do that by checking to see what's not working. Then go to each device and disconnect the wires. In the fuse box set your meter to ohms and place one lead on the #2 fuse wire going out and the other on the ground. If it reads infinity then the wire is OK. Connect the devices one at a time and repeat the test. If you get a zero resistance when you connect and test a device that's where the issue is.

Edit/add: You can also get a circuit breaker fuse of the same amperage and do the test with the circuit breaker. When the breaker trips after connecting the power you have found the culprit.

[wiredgeorge]

What is the fuse amperage? The color will tell you and it is generally on the fuse. I have never seen a fuse/circuit breaker but you can go to an auto parts store and buy a box of the appropriate size and just go through the devices on that fuse. When you say "zone 2", is that how that fuse is labeled?

[flybouy]

Originally Posted by wiredgeorge

What is the fuse amperage? The color will tell you and it is generally on the fuse. I have never seen a fuse/circuit breaker but you can go to an auto parts store and buy a box of the appropriate size and just go through the devices on that fuse. When you say "zone 2", is that how that fuse is labeled?

Here ya go George ... https://www.ebay.com/itm/40355748843...4a2813f4d45277
He said it was a 15 amp in the first post.

[wiredgeorge]

Originally Posted by flybouy

Here ya go George ... https://www.ebay.com/itm/40355748843...4a2813f4d45277
He said it was a 15 amp in the first post.

Mea maxima culpa! Since many of the DC fuses are 15A, perhaps buy a pack at Autozone. Blue.

[chuckster57]

Originally Posted by wiredgeorge

Mea maxima culpa! Since many of the DC fuses are 15A, perhaps buy a pack at Autozone. Blue.

I had an old boss that got real tired REAL FAST if you just kept putting in another fuse without trying to fix the problem first. He made me a 20A circuit breaker with a pair of blade connectors. Plug into the power side, then the load side. If it popped, you unplugged the load side and then started using a meter on everything that was on that circuit looking for a short to ground.

I had one trailer that actually had 3 separate shorts on the same circuit and I only “wasted” 2 fuses.

[wiredgeorge]

Originally Posted by chuckster57

I had an old boss that got real tired REAL FAST if you just kept putting in another fuse without trying to fix the problem first. He made me a 20A circuit breaker with a pair of blade connectors. Plug into the power side, then the load side. If it popped, you unplugged the load side and then started using a meter on everything that was on that circuit looking for a short to ground.

I had one trailer that actually had 3 separate shorts on the same circuit and I only “wasted” 2 fuses.

I thought it was a good idea to figure out what 12V gizmo was NOT working then unplug these gizmos. Put a fuse in and plug gizmo 1 back in. No pop? Go to gizmo 2 and plug it back in. No pop, gizmo 3; plug it in and if there is a pop, you may have found your culprit where one of the wires connected to gizmo 3 is touching a ground.

[sourdough]

You guys go about it the hard way. When I get tired of chasing a problem like that I've always found if I just hardwire across the fuse posts something will give down the line. May be a little smoke, may be a little melted something or the other (might be an electrical motor - btdt) but "poof", troubleshooting is done!! OP I say this in jest.

Pull the fuse, put a VOM on the load side to ground, you will probably peg the meter (whoops! my decades of using Simpsons and Tripletts is showing). Disconnect each of the items/locations served by that fuse (you should know that as those are the ones dead). When the meter drops to zero (infinity) you've disconnected the problem. If none of them clear it time to regroup and get serious.

[fdhoward]

Unplugging the exhaust fan is really hard/impossible. Built in and can’t find a way to get to electrical wiring.

Ran a jumper line from ground side of fuse to front of trailer. Pickup up that ground line and checked for continuity. All good. Checked ground to main ground in fuse box. All have continuity. Checked main hot feed to hot side of fuse box, all good.

Could a fuse box be shorting out?

[flybouy]

Originally Posted by fdhoward

Unplugging the exhaust fan is really hard/impossible. Built in and can’t find a way to get to electrical wiring.

Ran a jumper line from ground side of fuse to front of trailer. Pickup up that ground line and checked for continuity. All good. Checked ground to main ground in fuse box. All have continuity. Checked main hot feed to hot side of fuse box, all good.

Could a fuse box be shorting out?

The rests you describe are not the tests that vhave been recommended and will not diagnose your issue. The vent fan likely has an area (a cover with a screw) where the wire connection is accessible without removing it from the cabinet. If it doesn’t then turn the fan and light off and conduct the tests as has been outlined by several people previously.

If you actually suspect the "fuse box shorting out" then remove the wire connected to that fuse position and stick a fuse back in the holder. My money is on the fuse not blowing if you do that.

[chuckster57]

If you take out the filter, you should see the wiring if I remember right.

[Gord]

Originally Posted by sourdough

You guys go about it the hard way. When I get tired of chasing a problem like that I've always found if I just hardwire across the fuse posts something will give down the line. May be a little smoke, may be a little melted something or the other (might be an electrical motor - btdt) but "poof", troubleshooting is done!! OP I say this in jest.

Pull the fuse, put a VOM on the load side to ground, you will probably peg the meter (whoops! my decades of using Simpsons and Tripletts is showing). Disconnect each of the items/locations served by that fuse (you should know that as those are the ones dead). When the meter drops to zero (infinity) you've disconnected the problem. If none of them clear it time to regroup and get serious.

With a digital meter "0" ohms indicates a short circuit. A high ohms reading indicates a good circuit.

[sourdough]

Originally Posted by Gord

With a digital meter "0" ohms indicates a short circuit. A high ohms reading indicates a good circuit.

I wasn't clear. When the meter "drops" (a digital doesn't have a needle) to zero (meaning it reads nothing - infinity) the meter isn't seeing anything. I should not have said "zero" as that in fact would indicate a dead short, zero ohms and the "infinity" at the end of an analog scale just doesn't have numbers. My digital meters show "0L" if the line is open. A "high" ohms reading could be good or bad depending on the value you should be seeing and not just a good circuit.

[Gord]

Danny, I agree that a high ohm reading does not always equate to a good circuit. Cheers, Gord