I had noticed the yellow wire but wasn't sure what it was used for. So if i utilized the yellow wire i wouldn't need to use the regular red power wire? I have found a fuse which is the HVAC W/ignition it is currently in use but i pushed the red wire in next to the fuse and the radio seemed to turn on fine with the ignition on. I'm assuming the yellow wire just gives you the ignition options when you are programming?There should be a yellow lead coming out of the radio with a bullet type connector on the end, likely capped off with a clear cover. This is the ignition sense lead.
You can purchase an "official" Kenwood KCT-46 cable, which is basically a piece of yellow wire with a bullet connector to match the radio and a fuse holder and a 3 amp fuse. It's cheaper to make your own, though.
You'll need to locate an ignition switched power source to tap into. This will vary depending on your vehicle. Often, people will use fuse taps to do this, but they can cause issues if they are the type that jam in around the existing fuses. I've always found an unused accessory source to tap into, actually tying into a wire to prevent fuse box issues. On my old truck I tapped into an unused sun roof power lead (truck didn't have a sun roof, so the power lead was just taped off in the "A" pillar.) Figuring out exactly what you need to use for your specific vehicle will either take some work with a multimeter, or searching the internet for info on your vehicle.
Once you have that done, you need to go into the radio with the programming software (KPG-89) and turn the function on. There is a couple of options:
Ignition sense only - turns radio on/off with ignition.
Ignition sense and power switch - radio turns on/off with ignition, or with power switch.
The other option you can set is "timed power-off" This is where you can tell the radio to turn on with the ignition, and to turn off a set amount of time after the ignition turns off. This is a hand feature if you want to still use the radio after the ignition is turned off. If you start your ignition before it times out, it resets to normal.
So would it be a good idea to tap the yellow wire into that HVAC W/ ignition fuse i was talking about?No, you still need to supply power to the radio using the red and black leads. The yellow wire is only for the ignition control, it will not power the radio.
Your red and black power lead should come direct from the battery, as this will give you a clean/reliable source of power with sufficient current capacity for the radio to perform properly. Tapping into other circuits for the radio power can introduce all kinds of noise into your signal, and it's entirely possible that you will blow a fuse, or worse, if you attempt to power it off an existing circuit.
The yellow lead goes to an ignition switched source. When it senses 12 volts DC, it will perform the function that has been programmed.
So, you need three wires to do what you want. The black and red power leads need to go to the battery, with fuses within a few inches of the battery to protect the rest of the wiring. Don't skip this part.
The yellow wire needs to be connected to an ignition switched source, and fused close to that tap in point. Again, don't rely on other fuses that may or may not be there.
That should work, however any time you tie into power, you are introducing a path that noise can get into your radio. HVAC systems are notorious for having RF noisy blower motors. I'd suggest trying to find something a bit more quite, something without a motor.So would it be a good idea to tap the yellow wire into that HVAC W/ ignition fuse i was talking about?
Ok got it, what size fuse should i use for the yellow wire?That should work, however any time you tie into power, you are introducing a path that noise can get into your radio. HVAC systems are notorious for having RF noisy blower motors. I'd suggest trying to find something a bit more quite, something without a motor.
These types of fuse taps are a better choice, as they do not involve stuffing anything extra into the fuse socket:
ATC ATO Add A Circuit Fuse Holder Tap - The Repair Connector Store
(note, this is for an ATO fuse, you need to figure out exactly what type of fuses your vehicle uses and purchase accordingly)
The fuse taps that stick a piece of metal down in with the fuse tab have a bad habit of forcing the contacts apart, which can lead to intermittent failures down the road.
Got it. Hey thanks for all the help and info, really needed it!!Kenwood ships the KCT-46 with a 3 amp fuse. Using the same would be a good idea. Likely it draws very little current.
I use this set up on my work truck. I have a Kenwood NX-700 VHF and an NX-900 800MHz radio in there, same body radio as the TK-7180, same ignition switched power set up. Using the ignition switch feature with the power off delay works well. I have them set to 2 hours, which works well, and keeps the radios from running down the battery.
Well this thread is for a TK-7180 which only supports LTR trunking. Since there is no affiliation required for LTR, killing the power has no effect. If you have an NX with type D trunking, then yes your words are very wise.Just to add for other people reading about ignition sense.
If the radio is on a trunking system. The Red and Black should be powered all the time and yellow to ignition. The radio will not deregister if you hook Red to switched power.
The same applies to most all trunking radio's, Including Motorola radio's.
If the radio is powered on all the time and you use the power button to turn the radio on and off, you do not have to worry about ignition sense wire.
A lot depends on programing with some models/manufactures also.
Yes I understand, but unlike some people I did a search instead of starting a new thread looking for if the yellow cable needed to be programmed to work correctly.Well this thread is for a TK-7180 which only supports LTR trunking. Since there is no affiliation required for LTR, killing the power has no effect. If you have an NX with type D trunking, then yes your words are very wise.
But all in all, if a trunking radio suddenly disappears, there is no harm to the subscriber radio. The trunking controller may be confused for a time but will eventually figure it out. But as you mentioned this is not the polite way to do things.