back up lights, isolating dual switches

Okay I'm back at it again... pulled the entire set up from the F250 and will be putting it in an 09 F-150 FX4, this one doesn't have upfitter switches so I need to find a few wires. Was wondering if someone could send me down the right track... Looking for the reverse trigger, an ignition +, and a constant +, for the 09 F-150 FX4 prefferably all in the same area... Hoping some of the guru's pull this older thread up to see this so I don't need to post a new thread... thanks all

Good to see you back, though I had to reread the previous pages. And I have no idea what the pics were, but that's Photobucket for you (I use imageshack). I guess you understand the diode stuff etc, or at least accept that it did work? Not that I know your truck's wiring, but I run reversing lights thru a relay, especially when adding extra lights or spots, but sometimes just to take the strain of the (gearbox or other) reverse switch since IMO the typical 4-5A for 2x 21W etc bulbs is a bit taxing. (Otherwise I have to replace gearbox switches every 10-20 years! My current (or low-current) car is 45 years old.) That's relatively simple, I just reconnect the reverse switch output to a relay (eg, #86 if +12V) and run a new wire from the battery (via a fuse) through relay #30 & #87 to the reverse light(s). If I want a manual control, I insert a diode (1N4004 etc) and add the manual switch (also thru a diode) which gets its +12V from ACC or battery +12V (else maybe IGN) depending on what I want. Ok, the new power wire is a bit of a pain, but that is standard procedure for me for new or existing headlights, audio, etc. BTW - about a diode reducing current - NO. Or rather, it does not restrict or regulate current, it is simple a one-way valve. However, because it adds a voltage drop (eg, 0.7V), the load sees a lower voltage and hence its current usually drops. The only other restriction occurs when using an underrated diode - eg, a 1A IN4004 for a 15A load. The diode goes pop and burns out, hence (usually) open circuit and hence a current restriction - namely to zero Amps (ha ha). But that's the same as any underrated component, whether a fuse, wiring, connector, resistor, etc. (Though diodes probably never flame, unlike wiring and connectors etc.) In summary, a diode does NOT restrict current. However, the load may take less current because of its voltage drop. (It's important to understand the difference, but it's easy to see how some interpret that as a "restriction".) Not that diode voltage drops have significant impact when powering relay coils. It's different if diodes are in the power cable/path, but that's why relays are used instead. A typical example:- car "ECU" relays protect the ECU against reverse connected batteries, but there is no diode in the power path (eg, #30 & #87). Instead, a much lower power-rated diode is used in series with the relay's coil so that if the wrong polarity is connected, the coil does not energise, hence the ECU is not connected to its (reversed) power supply. The same trick is used for powering portable equipment when the diode's voltage drop is undesirable, or a high power diode is too expensive or big or hot etc.     I guess I've scared you off for another several months... Hopefully others' replies with the correct wiring details will be shorter and much sweeter. BTW - I love your user name!

Thanks for the break down oldspark, I got a grasp on it back when the thread was new with a full understanding and they've worked without a hitch since then... The photo's were scematics I drew up of the wiring for them, damn photobucket shut me off the month for too much viewing I posted a bad ass photo of a Ford emblem i took in the ad to sell my F250 and it got over 6000 views so they shut me down for too much bandwith useage. It'll be back next month and I've pulled the image everyone likes to look at. I just came back and reposted to the thread to see if I could get some help with which wires to pull from in the new truck... Really surprized it's been up this long and no one has posted up as to the wires... usually everyone's right on top of things like that...

Man this is getting to me from what I have gathered there should be a blue wire with no tracer in the passenger kick panel that feeds the rear view mirror reverse power for the back up camera which i don't have but the harness should still be there and active... I can't for the life of me find it... anyone have a better direction? There's like 15 harness plugs in and around that kickpanel... i'm looking for plug C215 for this blue wire...

Okay found the blue wire... it's blue on the top of the plug where you can't see it and baby blue on the bottom... but i've found it... and boy it's a bitch to get to I'm hoping i can even get a T Tap to it... next I need an ignition source stable enough to trigger a relay...  

T tap(Scotchlock IDC whatever) should NEVER be used in an automotive environment. Even suggesting them shows lack of ability.

Well I guess Howie won't be assisting in solving the problem...

You know this site used to be wonderful when you needed some help you could come ask... now all you get is people not willing to help anymore or people talking doodie about what you're trying to do... If you're not part of the solution you're part of the problem... and as far as T Taps I've used them in many situations in the cab of a vehicle and never had an issue... .

Your reply was wrong, you were supposed to think what am I doing wrong. There are 3 threads in the general section which might point the way. Sure I'll help but WTH does one need to bring on the domelight when the reversing lights are on, if you are looking to see something, surely that will kill your night vision?

You've got it backwards man... When I walk out to the truck and hit the key fob to unlock the doors the dome light and headlights come on till the truck starts or 20 seconds which ever comes first... So it's all lit up inside and to the front of the truck... but behind the truck is dark...  Ford trucks light up the front, Chevy trucks light up the rear, I want to combine the two and light up all around the vehicle... I also want them to be able to work off a toggle switch for when I need to load a trailer, and when I put the truck in reverse they need to light up so I can see behind me...

This is what I've come up with... We had to add a Cap since the dome light dims and causes the relay to Buzz...

Topic continued here: https://www.the12volt.com/installbay/forum_posts.asp~TID~131152