How dumb an idea is this?

[Pullstart 62,912]

My camper seems to have a short plaguing me.  It’s on the running lights.  I have chased wire, cleaned up, re-run, many spots thinking I got it.  Right when I get comfortable, I blow another 30 amp fuse.  How terrible does it sound to stick an auto resetting circuit breaker in the truck for the time being?  
 

I almost feel ashamed even asking this!  

[lynnmor 7,308]

I would do the troubleshooting with the truck disconnected so that you don't overload that wiring and cause another set of problems.  Connect a battery between the contacts on the trailer plug and use a circuit beaker on one of them.

 

If you ever tour an RV manufacturing plant, just watch how they run wires thru frame holes that were drilled with a dull drill and have burrs large enough to cut off your finger.

[squonk 41,155]

It would be cool at night with the lights blinking on and off! 

 

Actually if the short is bad enough, with a resetting breaker, you may end up with enough light back there to light up the night sky. Did you check all bulbs for the heck of it? You could take every bulb out and drive it around during the day. Then put in 1 bulb at a time and drive some more. Maybe when you complete part of the circuit and the short starts happening you can somewhat identify where the short is.

 

 

Edited June 16, 2023 by squonk

[squonk 41,155]

3 minutes ago, lynnmor said:

I would do the troubleshooting with the truck disconnected so that you don't overload that wiring and cause another set of problems.  Connect a battery between the contacts on the trailer plug and use a circuit beaker on one of them.

 

 

I was towing a car on a tow dolly one evening for my B-I-L on the NYS Thruway during heavy T storms once. I didn't know it but a mouse had chewed thru a wire on the dolly. It knocked out my tail lights at first and then my headlights. All I had to see with was other cars tail lights and my 4 way flashers. When I was able to stop and unplug the dolly the head lights came back on and I replaced the tail light fuse.

[Pullstart 62,912]

37 minutes ago, lynnmor said:

I would do the troubleshooting with the truck disconnected so that you don't overload that wiring and cause another set of problems.  Connect a battery between the contacts on the trailer plug and use a circuit beaker on one of them.

 

If you ever tour an RV manufacturing plant, just watch how they run wires thru frame holes that were drilled with a dull drill and have burrs large enough to cut off your finger.

I do my troubleshooting with my meter, and no truck or power source.  Running a battery and a breaker Ian’s a bad idea.  I know they are big turds on wheels… and some are just bigger turds than others.

 

35 minutes ago, squonk said:

It would be cool at night with the lights blinking on and off! 

 

Actually if the short is bad enough, with a resetting breaker, you may end up with enough light back there to light up the night sky. Did you check all bulbs for the heck of it? You could take every bulb out and drive it around during the day. Then put in 1 bulb at a time and drive some more. Maybe when you complete part of the circuit and the short starts happening you can somewhat identify where the short is

I have run a few dark sections with my 4 ways flashing, because my turn signal circuit is still good.  Do what ya gotta do, right?  Removing a bulb at a time isn’t a terrible idea.  Lots of different bulbs and different offshoots from the main harness!

 

Do you think this could cause a harmful situation?  Last thing I want is to loose the camper or the load!
 

[squonk 41,155]

16 minutes ago, Pullstart said:

I do my troubleshooting with my meter, and no truck or power source.  Running a battery and a breaker Ian’s a bad idea.  I know they are big turds on wheels… and some are just bigger turds than others.

 

I have run a few dark sections with my 4 ways flashing, because my turn signal circuit is still good.  Do what ya gotta do, right?  Removing a bulb at a time isn’t a terrible idea.  Lots of different bulbs and different offshoots from the main harness!

 

Do you think this could cause a harmful situation?  Last thing I want is to loose the camper or the load!
 

I'd go like stink trying to find the short. Worse case scenario run it without the running light circuit. Maybe run a new circuit to the tail lights only. If you're gonna use a breaker, go no more than 10 amps. If you run a 30 amper and the short is bouncing along at 20-25 amps things can still get hot

[formariz 11,987]

1 hour ago, Pullstart said:

I almost feel ashamed even asking this!  

Don’t feel so ashamed. Desperation sometimes calls for unapproved measures. I had an old Toyota truck many moons ago that  developed a similar problem . Truck would not start due to a blown 30 amp fuse that seemed to blow at startup. For about one entire year no one could figure out where the short was. Once new fuse was put in problem could not be duplicated and truck would be ok for months on end. Drove me and many mechanics nuts. Not to mention the cost of diagnosing it each time. It was nothing but a wild goose chase. Then somehow I learned about a self resetting fuse. It was a good truck and I didn’t want to lose it, but if it did burn up I did not care. So I went that way. Drove it for almost 10 years like that never had that problem again. 

[squonk 41,155]

I worked on a brand new Buick that would pop the fuel pump fuse randomly. Tore the entire car apart front to back. Ran a new circuit from the fuel pump to the fuse block. The exception was the molded sealed bulkhead at the fire wall. I spliced into it on both sides. Yup the fuse still blew. I cut open the bulkhead and there was the fuel pump power wire and a ground wire right next to each other damaged when the bulkhead was crimped together. 

 

Another brand new Buick. Electra Estate wagon with 400 interior lights and 200 cigarette lighters. Dome light wouldn't shut off. The lights operated when the door switches closed grounding a return wire on the circuit. Tore that car apart too. Screw for a trim panel that held the headliner up went thru the return wire completing the entire circuit to ground.

 

But the best one. Couple had a Corvette. Corvette was in the shop over night. Corvette got stolen and wrecked. Ins. co. paid them and they bought a brand new Cavailer Z24 convertible. Those 2 people were a PITA especially the wife. She smoked like a chimney. One day we had a gully washer T storm and here she comes into the shop with the top down drenched. She was on the NYS Thruway and the top would go back up!!  The was madder than a wet hen! The "lead mechanic worked on it and the fuse for the top was on the same circuit as the cig lighter! he changed the fuse and "couldn't find anything really wrong" 

 

She leaves and in a week she is back. Another storm and she's drenched again!  This time he replaces the lighter. She leaves. 2 weeks go by and yet again she's back drenched again. Lead mechanic refuses to work on it because she yelled at him!  Boss says I'm working on it. I tell him "Not for warranty time flat rate I'm not! "

He agreed to pay me as long as it took. I ran a new circuit for the lighter and put in a separate circuit with a manual reset breaker for the top. That was the end of that! 

Edited June 16, 2023 by squonk

[squonk 41,155]

Another thing Kevin your camper has slide outs doesn't it ? They are a prime location for a short. 

 

I would hate for you to have a problem on the way to the show. Then your family would have to bunk with @elcamino/wheelhorse 

[elcamino/wheelhorse 9,326]

I don't think so. Skunky and Randy will have the extra bed in the room. I  just have a single and very gassy at night.

[wallfish 17,012]

If it's a dead short, intermittent or not, the time it's going to rear it's ugly head and cause bigger issues is on the road away from home. Murphy's law is alive and well and think you might be friends. LoL

What about running a temp wire external and under and even up the back on the outside and into the back of the light fixture as a temp fix just for the trip? I don't know what those lights look like but assuming they come out from the face with a couple of screws so just throwing it out there.

 

[Pullstart 62,912]

17 minutes ago, wallfish said:

If it's a dead short, intermittent or not, the time it's going to rear it's ugly head and cause bigger issues is on the road away from home. Murphy's law is alive and well and think you might be friends. LoL

What about running a temp wire external and under and even up the back on the outside and into the back of the light fixture as a temp fix just for the trip? I don't know what those lights look like but assuming they come out from the face with a couple of screws so just throwing it out there.

 

being 40’ long and 13’2” high or so, there are markers all along the sides and the tail.  Top and bottom.  Lots going on…. 
 

33 minutes ago, squonk said:

Another thing Kevin your camper has slide outs doesn't it ? They are a prime location for a short. 

 

I would hate for you to have a problem on the way to the show. Then your family would have to bunk with @elcamino/wheelhorse 

 

two slides, but I don’t think any of these wires are effected by them. 
 

 

Good thoughts, y’all!  I know where there are a couple more sections of wire harness without loom, so I got some more to snake in.  I realized too that my fuses are of the mini flavor.  The parts store found a resetting fuse in a neighboring town that’ll be here Monday just in case.

[squonk 41,155]

59 minutes ago, wallfish said:

If it's a dead short, intermittent or not, the time it's going to rear it's ugly head and cause bigger issues is on the road away from home. Murphy's law is alive and well and think you might be friends. LoL

What about running a temp wire external and under and even up the back on the outside and into the back of the light fixture as a temp fix just for the trip? I don't know what those lights look like but assuming they come out from the face with a couple of screws so just throwing it out there.

 

Yup run a new circuit for the tail lights. The heck with all the clearance lights until you have time  to really fix it.

[Pullstart 62,912]

I managed to get about 9’ of wrapped loom into the rear bumper, the last place on the trailer not insulated.  Pulled a couple spares (an entire fuse box!) from a donor truck just in case my stash runs low, and so far (with no road movement) so good!

 

 

[wallfish 17,012]

2 hours ago, wallfish said:

Murphy's law is alive and well and think you might be friends. LoL

Wasn't it tires last time?

[Achto 27,609]

One thing to keep in mind - In side the walls of your camper, every DC wire connection is made with the dreaded Scotchlok connectors.

 

The throw together camper & enclosed trailer companies love them for their easy of assembly. Unfortunately they are also great source for electrical failure. 

 

[ri702bill 8,339]

47 minutes ago, wallfish said:

Wasn't it tires last time?

I thought the most recent was chickens!!!!

 

OK - 2 things came to mind. Had a Jeep Wagoneer that the dome light fuse would pop intermittently. (ever try to find the fuse block on a 60's or early 70's Jeep - there is none!! All indivual twist fuse holders scattered about - NONE were marked) Turned out to be the power wire was on the bare steel floor under the aluminum door sill trim plate, held down with 5 or so sheetmetal screws. Would only blow the fuse in wet weather. One screw had compromised the insulation of the wire - would arc to the screw when wet!!

 

My FIL ran a repair garage - he found it quickly pairing up your self resetting fuse with an inductive ammeter over the wire - when the current stops, there is your problem right below it !!

 

Guess who worked for the OEM supplier of almost all domestic 7 way, 4 way or 7 and 4 way trailer tow connectors - ME. (I was also actively involved in the design of the assembly and test equipment for this project) Stoneridge (aka Pollak) had the lions share of all the OEM supply - and the truck side connector did not come without issues. Some, not all, applications are such where the backside of the connector is subject to rocks and gravel bombardment from a rear tire. That can cause minute cracks that allow the ingress of moisture, causing a short...

Edited June 17, 2023 by ri702bill

[squonk 41,155]

I have 3 of those ammeters. Plus one I could clip in line with an adapter and watch the current draw. 

[SylvanLakeWH 25,600]

Hotel rooms don't have dc usually, so shorts are rare.

 

More room in a 40' flatbed for, you know, the return trip. 

 

Just sayin'...

 

[wh500special 2,187]

I’ve never tried it to do it myself, but I think the spacing in your 7-pin plug is just right that you can jimmy a blade fuse across the onboard battery wire and the running light wire. May need to twist the blades a bit to make it fit. 
 

pins 3 and 4 on the picture below. This presumes there’s no blocking diode or similar in your wiring. 
 

I saw this at an RV show once where the dealer had shorted these pins to light up the running lights for display.   This might make troubleshooting easier since you won’t have to hook anything else to the trailer to power things up while you tinker. 
 

Steve

 

edit: found a picture that shows what I mean 

Edited June 17, 2023 by wh500special

[JoeM 7,874]

13 hours ago, squonk said:

things can still get hot

Called letting the smoke out!

Lectrical stuff has that magic smoke built in the circuits.

Wrapped chewing gum foil around those old glass fuses more than once. Sat there chewed and waited for the smoke.

 

Had a guy that worked for me 30 years ago. invented wiring that changed color when overheated. It did work and he got into a big pissing match over patent stuff. Airplane mfg we interested, then wire manufactures got involved and he did not have enough resources.

 

Circle the kids and kin around the camper, install a low impedance shunt, (aka jumper), and see what starts smoking! there's your dinner!

or if the kin are to busy checking out the web. Grab the trail cams and position them. 

 

 

[JoeM 7,874]

This is where it gets dangerous for me. Been thinking about how to find that problem. 

What if you took a 60 watt light bulb and wired it in place of the 30 amp fuse. Turn on the circuit and note the brightness of the bulb. Jiggle wiggle the wiring. I know a lot of it is burred. and note any change in the brightness of the bulb.

IDK might work 

[Tractorhead 9,064]

However maybe it helps.

i had few Trailers, where the rear Lights was just wired to one side path (lights right) 

where they clamp on all side warning lights ( the yellow) and front lights of the Trailer.

as far as they was led technic, that was usable - but not fine.

 

After this customer had a gently rear crash, an Workshop changed the rearlights to bulbtypes and insert to big bulbs.

Before they where LED types with 3W after it was 2x10W bulbs each side and 2 additional 10w on the upper walls.

that was 60W and all the Rearlights, all routed to the right lightwire.

Because the wire dimensions was calculated only for led, the Ground wire was completely overburdened.

The reason was it melts inside the wire harness and burnt few other insulations what causes the wireharness do some uncontrollable things. After changing and reworking the complete wireharness and change few Bulbs to lower versions,

all was fine.

 

If an fuse with 30A blows, there is a massive short.

if it occurs only sometimes, watch about the situation when it happens, to find out the reason for it.

 

maybe the wire was hooked to something else, what drops too much current?

 

 

[squonk 41,155]

30 amps is way too much for a tail light/ running light circuit. If you need a 30 amper you better have at minimum 12 ga. wire running it.

[Tractorhead 9,064]

Hey Buddy,

i calculate at a Trailer

 

5W bulb type or led version 3W rear light  

3x 3W bulb type or led 0,5 W   side protection light up to 6m ,each m longer +1x

5w bulb type or 1W LED Outline light 

5W for a double taillight like on Bikecarrier.

on an 

 

that in worst case on an 10m trailer

5W+ 5W + 5W+ 21W =(7x3W)  first taillight + outline + bike carrier+ sideprotect

that will be in worst case at bulb types

36Watts!

 

36Watts :12V is a maximum current of 3Amps.

ok little spare for funny lights and things like surround and we stay at 5A 

an 1,5qmm wire is fine here until 10-15 meters. But an significant voltagedrop can be measured here allready.

 

if you load that with 30A thats 6 times overloaded and wireinsulation can allready melting.

maximum fuse rating here i would insert an 15A but normally 10A To protect wires 

 

 

There is something massive wrong no doubt.about it.