Diagnosing Dim Camper Tail Lights When Truck Headlights Are On

[Sped1]

Try it on a good battery,

The house deep cycles are each testing at 5.92 each….. is this normal? See Photo

Do you have a battery disconnect switch someplace near the battery.
Not that I know of....

Follow the positive wire off the battery. Is there an inline fuse that may have tripped when you installed the new batteries?
I'll check that !!

Your cable/pigtail should go to a junction box. Open it up and check the wire nut on the red wire which should be the power wire. Unscrew it and make sure there is no corrosion in the wires. Sometimes just from vibrations, that wire nut could loosen up and the wires disconnect inside the wire nut
Is this the cable junction box? See photo.....

 

[Laura & Charles]

5.92 not so good

 

[Sped1]

I'm sure it doesn't matter but I do have brand new AGM( glass mat) batteries.....

The mysteries continue......

 

[Rene T]

So it looks like you have two 6 volt batteries hooked in series to give you 12 volts. Is that right? Are you sure they are connected correctly?

Charles can you come up with a diagram showing how to hook up two 6 volt batteries in series? Maybe that’s his problem. They may be hooked up in parallel giving him only 6 volts all the time

Yes that is the junction box I was referring to.

 

[Rene T]

It’s hard for us to trouble shoot without being right there. It may be getting time to call in a mobile repair guy unless someone here has anymore ideas

 

[Sped1]

So it looks like you have two 6 volt batteries hooked in series to give you 12 volts. Is that right? Are you sure they are connected correctly?

The batteries are new.... I connected them the exact same way the old batteries were connected. I even went back and looked at the photos I took of the old batteries back in November and checked that the new batteries were connected the same way,,,,,,I did that yesterday .........
I'm now I hour 12 of diagnosis and I'm beginning to lose my mind.......

 

[Rene T]

Were the old batteries 12 volt and the new ones are 6 volt?

 

[TheBar]

Unless I’m wrong but I believe the OP should have 12 volt power at the red contact all the time when the camper batteries are hooked up. No need of the truck.

He said in his first post his house batteries were badly discharged at 11.7 volts. If the lights are fed from those discharged batteries that could explain dim tail lights, right?

By taking power from the fully charged truck battery to the camper lights we will find out if the lights are dim because of the low voltage camper batteries, right?

 

[Sped1]

Were the old batteries 12 volt and the new ones are 6 volt?

NO....
2 6 volts got replaced by 2 6 volts.....

 

[Sped1]

He said in his first post his house batteries were badly discharged at 11.7 volts. If the lights are fed from those discharged batteries that could explain dim tail lights, right?

By taking power from the fully charged truck battery to the camper lights we will find out if the lights are dim because of the low voltage camper batteries, right?

I understand what you're saying...... How do I do this?
I do have a 15 foot piece of 14 gauge wire......

 

[Rene T]

He said in his first post his house batteries were badly discharged at 11.7 volts. If the lights are fed from those discharged batteries that could explain dim tail lights, right?

By taking power from the fully charged truck battery to the camper lights we will find out if the lights are dim because of the low voltage camper batteries, right?

I don’t know. Like I said earlier, I’m not an electrician so now we’re getting into an area I’m not comfortable in. I think it’s time to get a mobile tech to figure it out. It may be something simple that a trained eye will pick it right out.

 

[TheBar]

I understand what you're saying...... How do I do this?

Stick one end of the wire in the Vehicle (truck's) plug at the red Aux 12v power socket in the left side of the picture below. Stick the other end in the camper plug purple tail/running lights socket in the right side of the picture. This tests the positive + side.

If the lights are still not bright make another jumper wire and stick one end in your jumper cable hooked to the truck frame. Then stick the other end in the white socket on the camper plug. This tests the negative ground. BE VERY careful to not touch both wires at the same time or to each other or you will get shocked and maybe a big spark.

If still not bright the low voltage is not the problem. Which means the plugs or wiring is the problem. Which is likely what caused the discharged camper batteries.

 

[CharlesinGA]

If there is 12v power sitting on the camper's 12v aux power terminal, the test Rene is suggesting should work fine. I have done this with my trailer, using the trailer's power to power the parking lights and also the brake lights as a test. I used to shove a two prong flasher assembly into the 12v+ and parking light terminal and make the lights flash, but I changed out the tag light to LED and the flasher no longer works (no resistance).

The OP needs to use the test light between the 12v+ on the camper's plug and the 12v- ground, directly opposite it on the plug, If that does not light the test light, then the batteries are switched off.

It is good to leave the truck out of this, as the camper's power can be used and should make troubleshooting easier.

Charles

 

[Rene T]

To the OP, you can take that 15’ of wire and do one last test.
To do this you will need the batteries fully charged by using a battery charger.
Connect one end of that wire to the same positive post where you got the 11.7 volts at the beginning of your post. Remember, they have to be fully charged. They should be 12.5 or greater. A second person can do this.
Then take the other end of that wire and insert it in the camper plug at the various contacts. DO NOT insert it in the ground terminal or the power terminal. Insert it ONLY in the brake light, back up lights, left directional, right directional and the running lights contacts. All these lights should go on.

If they do, what you just did was run a new hot wire from the batteries outside to the camper plug. If the lights work this way, then you have a problem with the red 12 volt power camper wire in the wiring. Either there is a break someplace in that wire or it may be disconnected inside that junction box. or there is an inline fuse which has blown or there is a battery disconnect switch that has been turned off. That switch could also be inside the camper someplace

 

[Rene T]

Going through this entire post I noticed something strange. In post #28, your 2nd picture shows the end of your camper plug.
Yet in post #35 and #36 you show pictures of the same plug but the contacts look completely different. Is it because of the angle you took the picture or is it different lighting.

WEIRD!!!

 

[Rene T]

One other thing. You mentioned a couple of times the interior lights work fine. Well you are probably plugged into shore power and those lights may be powered by your CONverter. You should have a CONverter someplace hidden away in the camper. If working properly, that CONverter also charges your camper batteries but it is at a much slower rate than a standard car battery charger. That converter converts 110 volt AC to 12 volt DC

 

[TheBar]

Never mind, see my next post.

 

[TheBar]

Going through this entire post I noticed something strange. In post #28, your 2nd picture shows the end of your camper plug.
Yet in post #35 and #36 you show pictures of the same plug but the contacts look completely different.

WEIRD!!!

You are right. Charles posted a picture of a Bargman and a Pollak type plug. SPED1 posted pictures of both types. I've never seen a camper with both types have you? SPED1 needs more attention from his mama. I'm out of this conversation.

 

[Rene T]

You are right. Charles posted a picture of a Bargman and a Pollak type plug. SPED1 posted pictures of both types. I've never seen a camper with both types have you? SPED1 needs more attention from his mama. I'm out of this conversation.

I see what you mean. Charles posted 2 types and the OP also did indicating he has both types and I’ve never seen that before. What I would say now is find a mobile tech to look at it. I tried my best to help him. I think I’m also probably done.

 

[gwinger]

Confused! What do the house batteries have to do with brake lights, turn signals and head lights?