Non-BMW Question - A Little Help

[adk749]

Hey everyone! My girlfriend is getting a new Jetta and I want to hardwire her GPS unit for her. I have tried to research and post onto some of the VW boards, but they are not nearly as helpful as us here! I am going to wire a cigarette lighter (picture attached). I know where to hook up the power wire and where to hook up the ground, but I have a few questions:

1) I am pretty certain the red wire is the power line and the black is the ground - correct?

2) Should I put an inline fuse on the red wire (power) between the cigarette adapter and power source? If so, how many amps should the fuse be?

Thanks so much for helping me out with my non-BMW questions!

[denial]

Check the male portion of the power adapter--that is, the part that's going to plug into the piece you got there. Many times there's already a fuse within that portion that's replaceable. If so, I'm *pretty* sure you'll be fine without another inline fuse. At least that's how I've done things in my previous vehicles. If it doesn't already have an inline fuse, well, let's wait for some other members to chime in...

[adk749]

[jkp1187]

Just a suggestion - might want to check TDIClub.com if you haven't already. A lot of hard-core VW DIY'ers on that site. Even if your girlfriend doesn't have a Jetta diesel, I'd bet the electrical stuff would be similar if not identical between the models.

[adk749]

Originally Posted by jkp1187

Just a suggestion - might want to check TDIClub.com if you haven't already. A lot of hard-core VW DIY'ers on that site. Even if your girlfriend doesn't have a Jetta diesel, I'd bet the electrical stuff would be similar if not identical between the models.

Awesome - thanks! Keep the advice coming....

[Lester]

Wire it to the fuse panel by purchasing an 'add-a-circuit' This way you don't have to disturb any original car wiring, and it gets to have it's own fuse. These are available at most auto parts/electronic stores. Just crimp the red wire to the connector and ground the black wire.

The add a circuit simply uses an empty fuse slot, or take out a fuse that is there - plug the add a circuit in, now bingo - you have a tandem fuse holder. The original fuse goes into one socket and the fuse for your new circuit goes into the second.

For the new circuit size, if you plan just to use it just for the GPS, check the manual - probably a 2 or 4 amp. Make sure to route any new wiring to avoid interfering with any moving or opening things on the car and secure it with some tie straps.

[stevenc]

Wire into the existing cigaret lighter power then you dont have to worry about a fuses, you will be covered by the cigaret lighter fuse.

[BlackjackMulligan]

Originally Posted by Lester

Wire it to the fuse panel by purchasing an 'add-a-circuit' This way you don't have to disturb any original car wiring, and it gets to have it's own fuse. These are available at most auto parts/electronic stores. Just crimp the red wire to the connector and ground the black wire.

The add a circuit simply uses an empty fuse slot, or take out a fuse that is there - plug the add a circuit in, now bingo - you have a tandem fuse holder. The original fuse goes into one socket and the fuse for your new circuit goes into the second.

For the new circuit size, if you plan just to use it just for the GPS, check the manual - probably a 2 or 4 amp. Make sure to route any new wiring to avoid interfering with any moving or opening things on the car and secure it with some tie straps.

This is good advice and what I'd do. The only piece I'd add is to look for a "switched" fuse/fuse slot so that the power is cut after you turn the car off. Otherwise you run the risk of draining the battery if you don't disconnect it each time you get out of the car.

You can easily find a switched circuit with a test light, or by simple trial and error with the gps unit it self. If you hook it up and it doesn't turn off when you turn off the key, keep trying other slots until you find one that does.

[adk749]

Awesome advice guys! I used the "add-a-circuit" for my radar detector in my 135i and it worked great. If there are blank slots in the Jetta, would some be higher "power output" (boy I sound like a retard) than others? Would I need to find one with particular power output, or are they all the same? I assume there is some "map" to the fuse box that would direct me.

As far as the fuse, I used two 10 amp fuses in my add-a-circuit for my radar in my BMW, were those too high? Sounds like 2-4 amps is kinda low. Thoughts?

[JimD]

The way to decide on the size of the fuse is to look at how much power the GPS draws. It should be available in the manual, sometimes on the unit itself, or from the manufacturer. If it is in Watts, you have to remember that Volts times Amps = Watts. A Garmin 7xx uses 10W maximum according to it's manual, for instance. So it should never blow a 1 amp fuse. A 2 amp wouldn't be terrible IMHO, however.

I may hardwire my Suzuki SUV. I would pick up the electricity on the wires leading to the accessory socket. They are switched. I might use an in-line fuse but probably won't. I see no reason for a short to occur on this circuit. But using a fuse is probably smarter. I would not put a female accessory socket in because then I would have to find a spot for it inside the dash and a lot more wire than I need. I would just solder the wires to the leads. I also plan to put the plastic base for the suction mount on the dash, run the wires up near the base and call it good enough. I will have wires showing for six inches or so but they won't be stretched over the HVAC and radio controls.

Jim

[adk749]

What happens if the amp is too big or too small? I assume that if it is too big, too much power might get to the GPS unit and blow it. If it is too small the right amount of power might blow the fuse. Is this right? I am still not sure what size fuse to put on this thing!

[Lester]

Originally Posted by adk749

What happens if the amp is too big or too small? I assume that if it is too big, too much power might get to the GPS unit and blow it. If it is too small the right amount of power might blow the fuse. Is this right? I am still not sure what size fuse to put on this thing!

The size of the fuse will not determine the amount of power that 'gets' to the GPS device. It is the other way around. The GPS device draws the amount of power it requires. If it is a power suck, then it will draw a large amount of amps. If a device requires 120 watts to operate, then 120 watts/12 volts = 10 amps. (Watts = volts x amps). If a device requires 12 watts to operate = then it requires 1 amp at 12 volts.

If the fuse is too small, then it will simply blow under normal load. If it is too large, then it will offer no protection in an over amperage. The normal factor is twice the rated amps. - so if the GPS manual rates the device at 24 watts = this would be 2 amps under normal load - so you would use twice that - or a 4 amp fuse.

[adrean8j]

This is good stuff. Learned something new today.

[adk749]

Originally Posted by Lester

The size of the fuse will not determine the amount of power that 'gets' to the GPS device. It is the other way around. The GPS device draws the amount of power it requires. If it is a power suck, then it will draw a large amount of amps. If a device requires 120 watts to operate, then 120 watts/12 volts = 10 amps. (Watts = volts x amps). If a device requires 12 watts to operate = then it requires 1 amp at 12 volts.

If the fuse is too small, then it will simply blow under normal load. If it is too large, then it will offer no protection in an over amperage. The normal factor is twice the rated amps. - so if the GPS manual rates the device at 24 watts = this would be 2 amps under normal load - so you would use twice that - or a 4 amp fuse.

Two more questions....

1) The manual reads "Usage: 5W max" So now what?
2) There is a fuse in the wire that is supplied for the GPS, so do I need to run one in-line from the fuse box? I would think it is now not necessary. Thoughts?

[adrean8j]

Originally Posted by adk749

Two more questions....

1) The manual reads "Usage: 5W max" So now what?
2) There is a fuse in the wire that is supplied for the GPS, so do I need to run one in-line from the fuse box? I would think it is now not necessary. Thoughts?

How about you tell all of us what GPS you are installing so we can look up the pertinent info.

[Lester]

Check the rating of the in-line fuse, double it and that is what I would put at the fuse panel. Leave the inline fuse in place. Now you have two fuses, for extra protection.

[adk749]

Originally Posted by adrean8j

How about you tell all of us what GPS you are installing so we can look up the pertinent info.

Garmin 265WT

[Lester]

The Garmin manual says to change the bulit in fuse to a 3A fast blow fuse. I would use a 5 Amp fuse at the fuse panel. Keep in mind the built in fuse will blow first.

[adrean8j]

Originally Posted by adk749

Garmin 265WT

LOL...I just bought the same NAV unit two days ago...great little unit for a low price. Lifetime Traffic, bluetooth, great screen resolution...a win, win IMHO...now this thread becomes even more interesting for me. I wonder if I could easily hardwire it to my 1er...

[The Cthulhu]

Originally Posted by Lester

The size of the fuse will not determine the amount of power that 'gets' to the GPS device. It is the other way around. The GPS device draws the amount of power it requires. If it is a power suck, then it will draw a large amount of amps. If a device requires 120 watts to operate, then 120 watts/12 volts = 10 amps. (Watts = volts x amps). If a device requires 12 watts to operate = then it requires 1 amp at 12 volts.

If the fuse is too small, then it will simply blow under normal load. If it is too large, then it will offer no protection in an over amperage. The normal factor is twice the rated amps. - so if the GPS manual rates the device at 24 watts = this would be 2 amps under normal load - so you would use twice that - or a 4 amp fuse.

Correct. Also, you can't "give" and electronic device too much current, only too much voltage. You can think of electricity as hydraulic pipes. Current (measured in Amps) would be analagous to pipe diameter and voltage to fluid pressure. It doesn't matter if you're siphoning water from a bird bath or an olympic swimming pool, the hose won't break. But if you hook it to a fire hydrant... :-/

Since everything is ~12V in a car, the real issue with wiring is making sure the switching is the way you want it. The cigarette lighter wire-in is classic because the lighter can handle plenty of current (it shorts across a coil to generate heat). The power also turns on and off with the car, so you can't drain your battery if you leave the device on.

[adk749]

Originally Posted by adrean8j

LOL...I just bought the same NAV unit two days ago...great little unit for a low price. Lifetime Traffic, bluetooth, great screen resolution...a win, win IMHO...now this thread becomes even more interesting for me. I wonder if I could easily hardwire it to my 1er...

Very easy to do on our 1ers. Just look at the V1 hard-wire instructions - should be pretty much the same for your new Garmin. Good luck!

[JimD]

BMW offers installation brackets and kits for Garmin GPSs. I bought the package for the Pro/Plus wide screen package. It seems to use the same bracket as for the nuvi 360 unit but the instructions say to install it 11mm towards the passengers side to accomidate the wider GPS.

I do not think the wiring for the nuvi 360 (it doesn't really come with much) or the nuvi 760 will help a lot with the 265WT. But the bracket should work, it has the normal Garmin ball mount you could clip the bracket for your 265WT to. To get the power, the instructions for the 360 would help you find the pins to tie into. You could either wire a female connector for the existing power cord or cut off the cigarette lighter male piece off the cable and just connect the wires directly (that would be my preferred). You bring the power wire out the hole for the bracket and it should not show much from the drivers side but a little more from the windshield side. It looks a lot better than wires all over the interior. And is more secure than a suction cup.

Search this site for pictures of other peoples BMW installations.

Jim