I'm currently rewiring a fifth wheeler junction box (on pin bar where trailer harness joins to van harness),all the light wires from the trailer harness (indicators, brake, tail & earth all good, but I'm now left with the blue brake wire and black reverse signal wire,and from the van harness is a 7mm red 12v live wire and a paired 4mm black /white wire (white going to earth).Any suggestions / help appreciated!CheersTerryJ
Leshill said
11:18 PM Apr 9, 2021
Do you need to connect the blue brake wire to the car plug -- to activate the van brakes ?
Do you have reversing lights on the van ?
The positive 12 volt 7 mm red wire --I would Isolate it with an electrical fitting ( or put a switch and exterior light on the van )
Isolate the other wires too. Ie the black / white wire -- seperate them and see what dosn't work. Someone may have something using the black wire now connected to the white wire to give it an earth.
Funny things do get done with wiring.
Good luck
TerryJ said
09:16 AM Apr 10, 2021
thanks Leshill
the blue wire from trailer plug will have to be connected somewhere for van brakes to work (thought that may have been what the small black wire in van harness may have been for?),
No reversing lights or camera on the van (and the black reverse wire from trailer plug harness is 7 mm!)
I s'pose now it shows that I'm not a auto electrician!
Cheers
Is the blue wire you are referring to connected to pin 5 of your plug? If so you will need a wire to the pin 5 on your tugs socket. This will go to a brake controller mounted in the cab of the tug. (If you are using the "7 pin round heavy duty plug & socket" it will be pin 7.)
The black wire, which pin is it terminated on? Have you managed to chase it back to its source?
TerryJ said
12:29 PM Apr 11, 2021
thanks PeterD,
Im using the Aust plug & socket diagrams re the large 7 pin round.
The blue wire is connected to pin 5 on my trailer plug and pin 5 on my tug socket, which is connected to the mounted brake controller in the tug.
The black wire is connected to pin 2 on the plug and socket.
The blue and black wires are the only unconnected wires on the trailer end of the plug,
on the van harness I have a 7mm red 12v active (assuming from the battery system in the van),
and the thin black wire (which was paired to a white wire which goes to earth),
I'm assuming the red active 12v is for battery feed to and from van?
I'm currently having the black wire sourced, I think that may be the connection for the 12v active from van,
(even tho' the connector diagram states the black is Reverse Signal, I have no reverse lights/signal/camera).
I also have 2 black wires coming in to the junction box from the breakaway brake switch, I'm assuming one for 12v+ and one for earth?
The tug is a 2015 Ford Ranger, and the socket inside the tub has been wired from the Ford 12 pin plug at the towbar.
Cheers, and thanks sincerely for your input.
TerryJ
PeterD said
07:01 PM Apr 11, 2021
If the blue wire is unconnected, do you have any brakes working on the Van? You have me confused, where is the free/unconnected end of the blue and black wires?
Regarding pin number 2. This was allocated to the "reverse signal." However, very few vans are manufactured with reverse lights (the only manufacturer I know who does is Spaceland Industries.) Van manufacturers have been thieving this pin to use as the 12 V supply to the van. This was OK back before absorption fridges were only supplied as tow-way fridges and only supplied the lights in the van. When three-way fridges appeared this pin on the smaller plugs would burn out the pin if the wiring to the fridge was heavy enough to power the fridge with minimal voltage drop.
The red wire, are you measuring 12 volts on it? If so it is probably the cable to charge the battery from your tugs alternator. If so, you will need to pair it with an earth cable and terminate it with an Anderson plug. You will need a mating plug to connect that through to the tugs battery (through a fuse at the battery.) Most people also use a large relay/solenoid near the battery that is operated from the ignition circuit. That is so you do not deplete your starting battery when you camp without disconnecting the tug.
There are several methods used to power the 12 V circuits from the tugs battery. Fifteen years and further back most manufacturers used pin 2 of the trailer plug to power both the lights and the fridge. As I said above, this was a bit of a failure, the fridges did not work properly. 12 pin sockets were introduced with 5 pins that will carry 35 A of current. The 12 V supply to the vans 12 V circuit is connected through pin 8 and the fridge through pin 9. After batteries were supplied with vans these large pins were found to be not big enough to supply the battery charging so Anderson plugs were introduced for the purpose. Some also use that Anderson plug to power the fridge, others use a second one for the fridge. There is no standard for these connections. Check with the previous owner (or the manufacturer if it's new) to find out how the van is actually wired.
"I also have 2 black wires coming into the junction box from the breakaway brake switch, I'm assuming one for 12v+ and one for earth?" those wires go to the breakaway circuitry. If you have a breakaway controller, when your van breaks away from the tug, the switch puts a short circuit across the terminals on the breakaway unit and it, in turn, operates the brakes on the van. (at the same time, it illuminates the brake lights.) If you do not have a breakaway unit, that switch applies the power, from your house battery, to the brakes when the van breaks away from the tug. I believe that switch is not robust enough to do the job on its own reliably.
Do you need to connect the blue brake wire to the car plug -- to activate the van brakes ?
Do you have reversing lights on the van ?
The positive 12 volt 7 mm red wire --I would Isolate it with an electrical fitting ( or put a switch and exterior light on the van )
Isolate the other wires too. Ie the black / white wire -- seperate them and see what dosn't work. Someone may have something using the black wire now connected to the white wire to give it an earth.
Funny things do get done with wiring.
Good luck
the blue wire from trailer plug will have to be connected somewhere for van brakes to work (thought that may have been what the small black wire in van harness may have been for?),
No reversing lights or camera on the van (and the black reverse wire from trailer plug harness is 7 mm!)
I s'pose now it shows that I'm not a auto electrician!
Cheers
Are you using the common trailer connectors as in this link? Australian trailer plug and socket wiring diagrams. If so which one(s.) I assume you are.
Is the blue wire you are referring to connected to pin 5 of your plug? If so you will need a wire to the pin 5 on your tugs socket. This will go to a brake controller mounted in the cab of the tug. (If you are using the "7 pin round heavy duty plug & socket" it will be pin 7.)
The black wire, which pin is it terminated on? Have you managed to chase it back to its source?
Im using the Aust plug & socket diagrams re the large 7 pin round.
The blue wire is connected to pin 5 on my trailer plug and pin 5 on my tug socket, which is connected to the mounted brake controller in the tug.
The black wire is connected to pin 2 on the plug and socket.
The blue and black wires are the only unconnected wires on the trailer end of the plug,
on the van harness I have a 7mm red 12v active (assuming from the battery system in the van),
and the thin black wire (which was paired to a white wire which goes to earth),
I'm assuming the red active 12v is for battery feed to and from van?
I'm currently having the black wire sourced, I think that may be the connection for the 12v active from van,
(even tho' the connector diagram states the black is Reverse Signal, I have no reverse lights/signal/camera).
I also have 2 black wires coming in to the junction box from the breakaway brake switch, I'm assuming one for 12v+ and one for earth?
The tug is a 2015 Ford Ranger, and the socket inside the tub has been wired from the Ford 12 pin plug at the towbar.
Cheers, and thanks sincerely for your input.
TerryJ
Regarding pin number 2. This was allocated to the "reverse signal." However, very few vans are manufactured with reverse lights (the only manufacturer I know who does is Spaceland Industries.) Van manufacturers have been thieving this pin to use as the 12 V supply to the van. This was OK back before absorption fridges were only supplied as tow-way fridges and only supplied the lights in the van. When three-way fridges appeared this pin on the smaller plugs would burn out the pin if the wiring to the fridge was heavy enough to power the fridge with minimal voltage drop.
The red wire, are you measuring 12 volts on it? If so it is probably the cable to charge the battery from your tugs alternator. If so, you will need to pair it with an earth cable and terminate it with an Anderson plug. You will need a mating plug to connect that through to the tugs battery (through a fuse at the battery.) Most people also use a large relay/solenoid near the battery that is operated from the ignition circuit. That is so you do not deplete your starting battery when you camp without disconnecting the tug.
There are several methods used to power the 12 V circuits from the tugs battery. Fifteen years and further back most manufacturers used pin 2 of the trailer plug to power both the lights and the fridge. As I said above, this was a bit of a failure, the fridges did not work properly. 12 pin sockets were introduced with 5 pins that will carry 35 A of current. The 12 V supply to the vans 12 V circuit is connected through pin 8 and the fridge through pin 9. After batteries were supplied with vans these large pins were found to be not big enough to supply the battery charging so Anderson plugs were introduced for the purpose. Some also use that Anderson plug to power the fridge, others use a second one for the fridge. There is no standard for these connections. Check with the previous owner (or the manufacturer if it's new) to find out how the van is actually wired.
"I also have 2 black wires coming into the junction box from the breakaway brake switch, I'm assuming one for 12v+ and one for earth?" those wires go to the breakaway circuitry. If you have a breakaway controller, when your van breaks away from the tug, the switch puts a short circuit across the terminals on the breakaway unit and it, in turn, operates the brakes on the van. (at the same time, it illuminates the brake lights.) If you do not have a breakaway unit, that switch applies the power, from your house battery, to the brakes when the van breaks away from the tug. I believe that switch is not robust enough to do the job on its own reliably.