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Originally posted by Medieval Dave
Depends if you want them on when the key is out, if not, then I would wire them as follows, which is about the standard way to wire fogs, either front or rear;
1. The power circuit. In minimum 2.5mmsqr cable (about 25A) but I would go 4mm if poss in case you add more lights.
Run as short as possible to the fuse. Remember that before the fuse the cable is unprotected so if copper touches the body it WILL burn. I reccomend fitting a little aux fusebox right next to the battery, they are about 4 pounds. For two 55w foglights use a 15A fuse. From the fuse run into the relay contacts then out the other side of the contacts to the first lamp and loop to the second.
take the earth of each lamp to a good local earth (any bolt onto clean bare metalwork) always cover your earth points with a good blob of grease.
Now when the relay is energised the lights will come on.
2. the control circuit. in minimum 1mm2 normally, but I would go 2.5mm unless you understand the fusing araingement of what you are tapping into - remember the wire must always have a bigger rating than the fuse that protects it or sooner or later it will end up in flames.
Find a wire on the sidelight circuit which is live when the sidelights are on. Tap into this and run to your switch
From the other side of the switch run to your relay coil, and from the other side of the coil to a good earth. Now when the sidelights are on AND the switch is on current will flow from the sidelight circuit through the switch and through the relay coil to earth. this will energise the relay allowing the power circuit to operate.
Notes:
1. remember the power and control circuits are seperate circuits and each must be protected by a fuse. In the above case we use the fuse of the sidelight circuit, if our new wiring goes wrong then we take out the sidelight fuse. If you just use the switch then you should fit a seperate fuse between the battery and the switch.
2. All the cable in your circuit must be capable of carrying more current than the rating of the fuse protecting it. Fuses are there to protect cables, not the lights on the end of them, it's cables that can set fire to your truck.
3. On your relay the symbol for the coil will normally look like a spring, and the symol for the contacts (the switch that closes when the coil is energised) will look like an arial view of a half open gate.
4. You don't need to have or understand the wiring diagram to pick up feeds to swotch relays. If you need to find a feed from the sidelights that is live when the sidelights are on for example then you can do it as follows with a cheapo voltmeter. This technique is called 'backpinning'
connect the black probe of your meter to earth (bare metal). chack you have done so correctly by setting the meter to OHMS or continuity (symbol like a horseshoe on some meters), then touch the red probe to another bit of metal and the display should drop to zero or close.
Now set your meter to Volts (DC). push the red probe into the back of the connector that goes to the light switch on the steering column. don't disconnect it, just push the probe in from behind. if that wire is not live then you will get 0V if it is live you should get between 12V and 15V. so flick the sidelights on and off and watch for the volts going up when the light is on and down when it is off. when you find one that does that then you've found the wire you need to tap into.
Hope that all makes sense, If not give me a shout.
P.S. if anyone up my end of the world wants help with wiring stuff I would be up for that, especialy if you are the sort of person that can do mechanical stuff without loosing a finger and can help me with those bits!
1. The power circuit. In minimum 2.5mmsqr cable (about 25A) but I would go 4mm if poss in case you add more lights.
Run as short as possible to the fuse. Remember that before the fuse the cable is unprotected so if copper touches the body it WILL burn. I reccomend fitting a little aux fusebox right next to the battery, they are about 4 pounds. For two 55w foglights use a 15A fuse. From the fuse run into the relay contacts then out the other side of the contacts to the first lamp and loop to the second.
take the earth of each lamp to a good local earth (any bolt onto clean bare metalwork) always cover your earth points with a good blob of grease.
Now when the relay is energised the lights will come on.
2. the control circuit. in minimum 1mm2 normally, but I would go 2.5mm unless you understand the fusing araingement of what you are tapping into - remember the wire must always have a bigger rating than the fuse that protects it or sooner or later it will end up in flames.
Find a wire on the sidelight circuit which is live when the sidelights are on. Tap into this and run to your switch
From the other side of the switch run to your relay coil, and from the other side of the coil to a good earth. Now when the sidelights are on AND the switch is on current will flow from the sidelight circuit through the switch and through the relay coil to earth. this will energise the relay allowing the power circuit to operate.
Notes:
1. remember the power and control circuits are seperate circuits and each must be protected by a fuse. In the above case we use the fuse of the sidelight circuit, if our new wiring goes wrong then we take out the sidelight fuse. If you just use the switch then you should fit a seperate fuse between the battery and the switch.
2. All the cable in your circuit must be capable of carrying more current than the rating of the fuse protecting it. Fuses are there to protect cables, not the lights on the end of them, it's cables that can set fire to your truck.
3. On your relay the symbol for the coil will normally look like a spring, and the symol for the contacts (the switch that closes when the coil is energised) will look like an arial view of a half open gate.
4. You don't need to have or understand the wiring diagram to pick up feeds to swotch relays. If you need to find a feed from the sidelights that is live when the sidelights are on for example then you can do it as follows with a cheapo voltmeter. This technique is called 'backpinning'
connect the black probe of your meter to earth (bare metal). chack you have done so correctly by setting the meter to OHMS or continuity (symbol like a horseshoe on some meters), then touch the red probe to another bit of metal and the display should drop to zero or close.
Now set your meter to Volts (DC). push the red probe into the back of the connector that goes to the light switch on the steering column. don't disconnect it, just push the probe in from behind. if that wire is not live then you will get 0V if it is live you should get between 12V and 15V. so flick the sidelights on and off and watch for the volts going up when the light is on and down when it is off. when you find one that does that then you've found the wire you need to tap into.
Hope that all makes sense, If not give me a shout.
P.S. if anyone up my end of the world wants help with wiring stuff I would be up for that, especialy if you are the sort of person that can do mechanical stuff without loosing a finger and can help me with those bits!
i,ll probably blow the thing up!
Your much more advanced in your gagetry
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