Truck Camper Power Problems...Need Help

[sledhead5000]

So I recently bought an old truck camper and have it on the back of my truck ready for a two week camping trip starting this Friday and I can't get the electrics to make sense.

Because we'll be driving a lot and staying in places that don't have plug ins, I wanted the camper battery to charge off of the truck. After running a negative wire from the camper battery to the truck frame, and a positive wire from the camper battery to the truck battery (10 gage, with 30amp fuse and isolation switch on the positive wire), all of a sudden nothing in the trailer works unless the isolation switch is closed so the power can come from the truck battery.

With that switch open, the only thing I've changed is a camper battery negative to truck frame, yet nothing now works. All the fuses are fine, and what's even stranger is that the voltage across the camper battery stays the same (at 12 Volts) whether the switch is open or closed (truck battery voltage is 14).

Any suggestions on what on earth is going on?

Attached is a simplified wiring diagram. The only thing I can think of is that somehow the connection to the truck frame has caused the problem somehow.

 

[overkill131313]

take a set of battery jumper cables and put one end to the neg on the camper battery, and then clamp the other end to the neg ground strip/bar/(where ever the camper had its ground) and if things work then you know what to fix......but it sounds like a ground issue from the camper battery to the camper it self...... just my 2 cents!

if your coming this way.....I can fixer for ya!

 

[Summiteer]

It sounds like the negative of the camper battery is isolated from everything. You say the camper is old, I'd check the continuity of the cable on the negative of the camper battery.

 

[sledhead5000]

Quick check of the camper battery negative terminal looks okay. Wire was fully connected. Everything on the camper used to work before I attached those two wires. After work today I'm going to pull off the connection to the truck negative and see if everything goes back to working.

If that doesn't work I'll look more at the camper negative, but it used to work and I haven't adjusted it.

Couple of additional notes, the positive terminal on the truck is quite corroded I noticed while hooking up the wire yesterday. I cleared away most of the crap tho so the connection should be okay. And the negative connection to the truck frame is a bit rusty.

 

[Garryese]

Not sure if I understand this: You moved the camper battery negative to the truck? If so, you need to add another wire from the camper battery to whereever it was before you moved it or ground the camper electrical system to the truck.

If you added a ground from the camper battery then you likely lost connection (corrosion) on the camper ground right at the battery.

 

[sledhead5000]

Didn't move anything... I added the wires shown in red which essentially make the camper and truck the same ground.

Another thought occurs, is it possible for an AGC 30amp fuse to blow without it looking blown? I never tested it or the fuse holder... if that fuse has blown it would explain why nothing works unless the switch is closed. Still doesn't explain why the camper battery voltage doesn't equal the truck's battery voltage though.

Damn electrical ghosts.

 

[Summiteer]

Didn't move anything... I added the wires shown in red which essentially make the camper and truck the same ground.

Another thought occurs, is it possible for an AGC 30amp fuse to blow without it looking blown? I never tested it or the fuse holder... if that fuse has blown it would explain why nothing works unless the switch is closed. Still doesn't explain why the camper battery voltage doesn't equal the truck's battery voltage though.

Damn electrical ghosts.

If the camper battery fuse is faulty you basically have the camper battery isolated from everything, its voltage won't match the truck battery.

 

[fhe]

Didn't move anything... I added the wires shown in red which essentially make the camper and truck the same ground.

Another thought occurs, is it possible for an AGC 30amp fuse to blow without it looking blown? I never tested it or the fuse holder... if that fuse has blown it would explain why nothing works unless the switch is closed. Still doesn't explain why the camper battery voltage doesn't equal the truck's battery voltage though.

Damn electrical ghosts.

Yes, you can get a fuse which has a fault not detectable by eyesight.

 

[TylerG]

Didn't move anything... I added the wires shown in red which essentially make the camper and truck the same ground.

Another thought occurs, is it possible for an AGC 30amp fuse to blow without it looking blown? I never tested it or the fuse holder... if that fuse has blown it would explain why nothing works unless the switch is closed. Still doesn't explain why the camper battery voltage doesn't equal the truck's battery voltage though.

Damn electrical ghosts.

test the fuse with an ohm meter

 

[fhe]

Did you measure the voltage between the negative side of the camper battery and the line side of the fuse ( the live side of the fuse that you have now connected to the positive of the truck)?