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Loss of trailer running lites


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Yesterday before leaving Ft Meyers, all lites were working on the precheck, 4 ways, tail lites, indicators, hi-low and brakes. I could see the reflection of the brakes in the rigs window behind me.


I turned on the fridge and heard what sounded like a breaker pop in the dash area but didn't think much of it. Figured warm juice would do for the day and I'd check it out later.


In the evening after turning on the running lites it was obvious the trailer lites were not on but the truck's were. I stopped and moved the plug around, it was secure, still no joy.


The truck does have a Jackalopee.


The trailer lies went out a few months ago and I traced the offending wire as far as the Jackalopee and recall it changed from one color going in to a different one coming out.


That particular problem was attributed to road debris in the plug...I was suspicious of the finding.


Not much in my book about fuses, fridge or running lites trouble shooting so here are the questions before I dive into something I'm not well versed in.


- Is the fridge circuit tied in with the running lites?

- Should anything be tied into either?

- What fuse or breaker is each one.

- Are they numbered or color coded?

- Is it a fuse or breaker and if a breaker is it re-setable.


It's fine to fix the problem, more importantly, I want to know what caused the issue to begin with.


Have I missed anything?



- I don't know if Volvo would be much help with this.

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check under the fuse cover for a diagram for the fuse location. On a 610 it is in the center of the dash on top.

Also check for blown fuse with a meter.


The fridge maybe the problem that caused your situation .

Just need to start looking what is happening


Safe Travels, Vern

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I could but the people who have electrical smarts will laugh.

This same problem cropped up on my way South just after New Years, the tech at Camping world said it was a buildup of debris in the plug or receptacle.


At that time the trailer plug was in far enough to be behind the lug on the truck receptacle plate so I didn't buy the explanation.


Same thing happened again yesterday, switch on the lights, truck lights came on but no trailer lites. Got out at earliest chance, disconnected trailer cord, have a look, nothing obvious, wiggled plug in receptacle, still nothing. Made last 30 miles to Destin in the dark with no trailer running lites.


Volvo book I have didn't provide any help.


Today I started to try to figure it out. The dash area was where the click or "popped breaker noise" came from so that seemed to be a good place to start. Began looking for fuses and breakers, # 9 fuse, a yellow 20 amp mini fuse in the in cab truck fuse panel was for trailer running lites and it looked OK.


So now it is time to look at the Jackalopee book. Truck trailer lites are a brown on the left and pass thru Jack turning to green on the trailer or right.


At this time my under body ditch lites were on as well as truck running lites and I noticed red led's lit on the left side or truck side of the Jackalopee box. They, I figure, show power coming into the Jack box.

Also the turn signals were on and working and there was a red led on the truck or left side of the Jack Box as well as the trailer or right side.


Seeing as turn signals were working, I figured the 2 red led's indicate power was coming into the left side of the box and exiting on the right or side.


The brown truck running lite wire has a red led lit on the left side as well as the green trailer running side was lit up red so I figured there was juice to the trailer side of the Jackalopee. So my problem was downstream from exiting the Jack box.



So all this tells me there is power to the jack box and exiting the trailer side, green, of the Jack box but not to getting to the receptacle on the truck.


I only have a very simple lite tester, a probe, needle kind of device you poke thru the covering on the wire. Then clip the other end to a grounded terminal. There was power to the screw terminal on the truck plug, and now to the blade inside the receptacle itself.


I backed the truck so the trailer cord could reach the truck end and plugged it in. It worked. Ran thru the checks to make sure all was working correctly then buttoned things up..


This is the second time this has happened so a new plug and receptacle will be picked up at the earliest opportunity. In the meantime I'm going to make up a sanding tool to clean up the plug and receptacle connections.


So for now they are working.


Initially when I used the circuit tester on the blades of the truck receptacle the green running lite blade did not lite up, hence the backtracking.



You asked for an explanation, there may be others more mechanically challenged than me.

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Good job sometimes we forget that with the LED lights on the Jackalopee, that's the first and easiest place to look first inorder to norrow down if it's the truck or trailer.


That being said I have a ???? For Henry.

How good dose your power connection need to be for the led to light up? What I mean is could there still be a weak ground or power that would let the LED light up but not enough to power or good enough ground for your lights?

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LED's come in different varieties, in a Jackalopee they are high output (lumens wise). They require 20 mA of current at around +2.4 VDC (minimum) to light up. The current has to be limited otherwise they will burn up.

Since everything in a Jackalopee is 12 VDC (way above 2.4) there is a 480 ohm resistor in series with each LED to limit the current.

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No idea on actual reliability, but it looks to be very well made. Not cheap I know, but I'm considering it--the standard 7-pin plugs don't last long on the front of the towed car.

45' 2004 Showhauler -- VNL300, ISX, FreedomLine -- RVnerds.com -- where I've started to write about what I'm up to

Headlight and Fog Light Upgrades http://deepspacelighting.com

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