flyingwil
Supporting Sponsor - Sierra Expeditions
I am in need of some help here...
As you may have read I recently installed a bed bar with some lights in my build up thread. I want to tie my bed bar lights into my reverse light so that when I shift into reverse the lights on the bed bar lights come on. However I also want to be able to turn them on using the switch in the cab with out turning on the stock reverse lights.
I have done some research and the best I can come up with is this from TTORA:
Now if I splice into this similar to this with a 1N4004 diode in series with the OEM reverse light feed to the relay. This should isolate the OEM reverse light circuit from the switch, which is going to feed the same terminal on the relay, so when I activate my aux switch to turn the relay on, it will not back feed the OEM reverse light circuit. I just don't know how the OEM circuit works and it may not appreciate 12V being fed back into it. The effect of the isolation is that the normal reverse lights will not come on when I activate the aux switch.
Is this correct? Anyone know?
As you may have read I recently installed a bed bar with some lights in my build up thread. I want to tie my bed bar lights into my reverse light so that when I shift into reverse the lights on the bed bar lights come on. However I also want to be able to turn them on using the switch in the cab with out turning on the stock reverse lights.
I have done some research and the best I can come up with is this from TTORA:
wrooster on TTORA said:...the stock wiring, if you try to use it to power the aux lights, will result in very dim aux lights and/or a blown reverse light fuse. so you must use a relay to power the aux reverse light circuit. it is dead simple and no different than using a relay to power your driving lights up front.
You can of course use any 12V automotive relay for this application, as long as A) the current drawn by your light(s) does not exceed the relay rating, and B) the tabs on the bottom of the relay mate with standard 1/4"-width fasten tab connectors. the latter makes it easy to wire to the relay, and you don't need to buy a relay socket.
now the hard part, or what *should* be the hard part -- getting the relay to turn on when the truck is in reverse.
note 3: what i'm about to tell and show you is applicable to my 2002 V6 4WD auto Xtra cab. i believe that most models should be very similar, if not the same, to my setup. or, at least that's what the OEM wiring manuals tell me.
under the driver's seat is a connector block that basically attaches the wiring harness at the front of the truck to the wiring harness to the back of the truck. pretty much everything that goes out back goes through this connector, which is designated "BN7". on pin 22 of BN7 is the circuit which is energized when the truck is in reverse. this is the circuit that drives the OEM backup lights, and this the circuit we are going to use to drive our relay.
your first task... find BN7 on page 1 of:
http://misc.mmdsi.net/tacoma/tacoma-manual/Wiring_Manual/03tacoma/systemci/027bl.pdf
see the RED wire with BLACK TRACER (R-B) going into and out of pin 22 on BN7? that's your target! you'll note that it is the same for manual or auto.
your second task... find BN7 at the top of page 10 of:
http://misc.mmdsi.net/tacoma/tacoma-manual/Wiring_Manual/03tacoma/electric/connecto.pdf
the depiction of BN7 on the right is how you will be seeing it in real life. the mated pair of BN7 is mounted to a bracket underneath the driver's seat. with the seat still in place, you will be looking at it from the perspective of the right side diagram, with pin 22 at the lower right hand corner. this is the circuit we need access to.
take off the driver's side door threshold; 4 screws hold it in place. gently pry it up as there are some expanding plastic snaps that hold it into place.
now we need some pics...
threshold removed:
there is a pinch-clip that holds the rug over the wiring channel that needs to be undone. then, as shown, gently flex the rug up behind the front seat mounting bump.
looking under the rug, you can now see connector BN7, specifically you are looking at the half on the right hand side that i discussed above.
you may need to undo a bit of electrical tape and/or snip a plastic tie wrap to get to the point above. basically you need to put the three-way clamp-on splice connector onto the RED with BLACK TRACER wire which goes into position 22 on BN7 (again, lower right hand corner).
shown in the pics above is a new WHITE WIRE already tapped into the light blue three-way clamp-on splice connector, which in turn straddles the RED with BLACK TRACER wire. these splice connectors simply clamp over the existing wire using a pair of pliers, and take seconds to put on.
that's it, you are tapped into the reverse light circuit! nothing to it, almost like the Toyota engineers knew it was coming. put a tie wrap back on if you took it off, and tape over the splice as well. you are done under the seat.
now then...
which way you run the splice wire and where you mount the relay is a matter of personal preference. in my case i already had +12V power in the cubbyhole behind the driver's seat in my Xtracab. this meant, for me, it was a natural place to both run the wire to the aux reverse light from, and place the relay in. hence, my wiring is all done in the cubbyhole. in some cases, it will be easier for you to do the wiring up under the dash, in the engine compartment, or you could even leave the relay under the seat next to BN7. again, it doesn't really matter where you put the relay now that you have access to the reverse light circuit.
so wherever you mount the relay, simply run the reverse light circuit wire to that location. this lead goes to one side of the relay COIL. the other side of the relay COIL goes to ground. again, this is no different from setting up for driving lights.
stop and check here: when you put the truck in reverse, the relay should click. ...
Now if I splice into this similar to this with a 1N4004 diode in series with the OEM reverse light feed to the relay. This should isolate the OEM reverse light circuit from the switch, which is going to feed the same terminal on the relay, so when I activate my aux switch to turn the relay on, it will not back feed the OEM reverse light circuit. I just don't know how the OEM circuit works and it may not appreciate 12V being fed back into it. The effect of the isolation is that the normal reverse lights will not come on when I activate the aux switch.
Is this correct? Anyone know?
