tapping the wire into map light assy for overhead navigation system

[abin]

I am planning a project to wire my new purchased Garmin C320 navigation system. The C320 comes with a cradle which takes power from 12V DC outlet located next to shift gear. I looked around and managed to place the navigation set sticked on windshield underneath sun visor. I found it has good satellite reception and it is easy to read -- like an overhead console. (I will have picture posted soon)
The problem I run into is, the wire from cradle to 12V outlet has to go through windshield and stereo console. It is really ugly and my girlfriend think I should find a better way to resolve it or she would ask me to buy an in-dash one, which is expensive. I spent only $400 for my C320.
The idea I have is to tap the wire into map light unit. By stealing power from the map light before the switch, I will be able to turn on the navigation set when I open the any door. When I turn off the ignition and close the door, the navigation system supposes to shut down by itself at the time when the left-on map light is turned off by the system.
A plan is a plan. Before I start my hand-on, I would like to get suggestions from folks with experiences on this.

 

[599er]

Well first things first (obviously). Is the map light good for 12V?

 

[abin]

Well first things first (obviously). Is the map light good for 12V?

I don't know. But I need to find it out. The C320 needs 12V to power and charge its battery. I "suspect" that there can be a 12V wire available for me since I have sunroof in my 4 Runner. But, this is just a guess. I may want to spend 10 bucks to get the tech info from Toyota site for the availability. But my plan can be this,
Open the map light assembly
Check the voltage
If the 12V wire is not available, replace the assembly
Job done

 

[Bluto]

I've pulled my map light assembly down to install one with homelink. There should be a constant 12V there. But with constant power, you'll have to remember to power ON/OFF the GPS manually. If you use accessory power, it will turn on and off with the key. With the moonroof there probably is accessory power up there.

You could also run a wire along the headliner and down the A-pillar to the fuse panel. I did this when I had a radar detector.

 

[abin]

Thanks, Bluto for the info.
I would open the map light assembly (this evening) and confirm if there is a 12V power source.
If the answer is positive, then my plan will be,
wire the wire from navigation system cradle through a pillar for auto dimming rear view mirror
have it tapped to the 12V power source.

I may have to power on and off the navigation system every time when I get on an off as Bluto said. This will be different from what I am doing now, with the 12V DC outlet next to the shift, Ithe system will be powered up when the ignition is on, and power off 30 seconds after it is off.

What I am thinking is, to take the advantage from when people leaving map light on, the system will turn it off after ?? minutes and when the door is open, the map light is on. I did the experiment several days ago, and it seems work. I hope it would do the same way for the navigation system.

In any cases, I will try to take the pictures when I work on this. Hopefully, the last picture would show a clean and working overhead navigation system.

 

[Whoknows]

wire tapping.....

You might want to locate the 12V to the moonroof. I don't know its location, but that would allow you GPS to be powered with the ignition on, and it would turn off at either the opening of any door, or 45 seconds (whichever comes 1st). That is how the moonroof works. If you sit in your truck, you can still operate it for 45 seconds, as long as no one opens a door.

 

[abin]

Re: wire tapping.....

You might want to locate the 12V to the moonroof. I don't know its location, but that would allow you GPS to be powered with the ignition on, and it would turn off at either the opening of any door, or 45 seconds (whichever comes 1st). That is how the moonroof works. If you sit in your truck, you can still operate it for 45 seconds, as long as no one opens a door.

should have thought about this one. The timing for operation, turning on when the ignition is on, turning off when the door is open or 45 seconds after the ignition is off just like the how the power windows work, definitely is ideal for me.
who knows, thanks.

 

[Whoknows]

Sure thing!

Let us know how it goes.

 

[benk777]

Any updates on the status of your mod?

Ben

 

[abin]

Was really busy this few days.

The work is done. I have pictures attached as below.

 

[abin]

This picture shows the wire goes through A-pillar (for auto dimming) to map light assembly. So, no additional drill required.

 

[599er]

Very nice.

I'd love to mount my Garmin GPS V right there, but I've resigned to resting it on top of the cup tray (extended halfway out) for the time being. Like you, I just don't have the time (or when I do, I don't feel like it) to hard-wire it into that same location.

 

[abin]

The way it works is as followings,
When I open the door or push any button on the key fob, the navigation system get powered on. When I remove key from ignition and have the all doors closed, the navigation will stay on for 10 or 20 minutes, then it is off completely, not even in battery charge mode. This ensures battery will not be drained.

You may find I positoin the navigation system a little bit lower than what it can be on the windshield. I have no problem in receiving SAT signal in most areas, but putting it a bit lower, at about same position of rear mirror, proves it works a lot better in shady areas. The overhead position is a lot better than putting it on dashboard.

 

[599er]

The overhead position is a lot better than putting it on dashboard.

I agree. Most persons will find it easier to look up at the nav unit and keep their eyes on the road than to look down.

 

[abin]

Very nice.

I'd love to mount my Garmin GPS V right there, but I've resigned to resting it on top of the cup tray (extended halfway out) for the time being. Like you, I just don't have the time (or when I do, I don't feel like it) to hard-wire it into that same location.

The motivation of doing this comes from the 12V outlet next to the shift making the C320 power cord traveling through gear, stereo, vent, to windshield. My GF doesn't like it since she has a in dash factory navi. in the car her dad have. IMO, the overhead position is better than the factory nav, and my GF likes it when the work is done. It took me whole evening and cut three wires only to find the first one is working (with enough voltage). But, I believe the effort is worthy, and I stayed in garage when it snowed out. If I do it again, it will take only 30 minutes to complete.

 

[abin]

I agree. Most persons will find it easier to look up at the nav unit and keep their eyes on the road than to look down.

yes. as you can see, it is at same level as the rearview mirror.

you may agree further that how many times we listen to voice guidance than look at the nav screen. my experience on this is, by putting it overhead, you can easily separate the nav voice from stereo since they come from different direction.

Thanks to all suggestions I received from folks.

 

[benk777]

Can you give details on what wire you tapped and where? I need to do the same for my Valentine 1 radar detector. Having the curly cord go past my factory nav is nasty. Any and all details will be appreciated. Thanks.

Ben

 

[abin]

Can you give details on what wire you tapped and where? I need to do the same for my Valentine 1 radar detector. Having the curly cord go past my factory nav is nasty. Any and all details will be appreciated. Thanks.

Ben

So I helped my GF's brother and took a few pictures. He bought one unit after I showed him the work. Most pictures are not so good because of poor focus, but I believe these two should be enough.
The process did not take too long.

 

[abin]

You first remove the map light assembly.

Use the right and left end two wires to tap into. Be careful when you remove the map light assembly so that it is not broken.

 

[abin]

red is fire, white is neuture.