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Got tired of my GPS interrupting my phone calls. Got tired of my phone calls interrupting my GPS. Bought a Magellan Roadmate 9412T-LM 7" GPS for $100 on Ebay. Looked at my useless rear view mirror and took it off the stem. Took the stem off the window. Much to my surprise the ball on the stem matched the socket on the Magellan. (After I took a grinder and removed the little spike). DONE! Perfect location for my eyes and ears. Perfect location for my reach. Does not block vision any more than the mirror did. Power is 5" away at the lights and one can hide any adapters and connections they wish up there. Dash cam hides behind GPS. Much easier for me to glance at GPS up high than down low.
 

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I will be doing this Sunday. I got a good deal on the Roadmate 9416T-LM 7" on amazon. Thank you for sharing!
 

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Well, got my GPS unit mounted up. What a snug fit with the 7" display. If anyone plans on doing this is might recommend going one size smaller. Maybe a 6" or 5" unit.

I just need to route the power cord up into the headliner
 

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Well, got my GPS unit mounted up. What a snug fit with the 7" display. If anyone plans on doing this is might recommend going one size smaller. Maybe a 6" or 5" unit.

I just need to route the power cord up into the headliner
Nice job. About that snug fit, mine was snug too but the semi-soft headliner adapts to the tight fit and keeps the screen from bouncing around so I am fine with that. DID YOU FILE THE SMALL PIN off the ball? That gave me a little more freedom of movement. One thing I have since discovered, the GPS turns itself on when the dome lights get turned on due to where I tied it in. That is fine in the morning but not so fine if I am getting something out of the truck in the driveway in the evening. I will look in the settings for an "auto-on" feature to disable but if it does not have one, I might add a black toggle switch up in the headliner. If one pulls power from another source, this is not an issue.
 

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Nice job. About that snug fit, mine was snug too but the semi-soft headliner adapts to the tight fit and keeps the screen from bouncing around so I am fine with that. DID YOU FILE THE SMALL PIN off the ball? That gave me a little more freedom of movement. One thing I have since discovered, the GPS turns itself on when the dome lights get turned on due to where I tied it in. That is fine in the morning but not so fine if I am getting something out of the truck in the driveway in the evening. I will look in the settings for an "auto-on" feature to disable but if it does not have one, I might add a black toggle switch up in the headliner. If one pulls power from another source, this is not an issue.
Yes I removed the nub with my dremel tool. I was thinking of denting the headliner in a little. It is keeping the gps at its most bottom position which is stressing the mirror mount to the windshield. I will play around with it in the daylight tomorrow when I am working on wiring the unit up in the head liner.

I finally figured out how to get the dome light removed. Tomorrow I am going to tap into the power source that feeds the dome light. While I have it removed I am changing the bulbs to LED bulbs. I may check the wiring harness that the dome light ties into to see if there is a constant or Ignition switched power source in that harness.
 

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I tapped into the dome light connector with the three wires, not the two. I did not put much effort into it. The first two wires I checked with the meter had the power so I went there. I figured the on/off switch on the GPS would be all I needed. But the GPS will turn on if I go out in the driveway and get something out of the van this evening for example, and stay on. I did not figure out why that is yet. I might mess with it tomorrow as well.

My unit fits tight but not to the point of causing stress on mirror mount. I wonder how hard it would be to remove the mirror mount from the windshield, drop it down 1/4" and glue it back up there? I had an uncomfortably tight fit when I tried to install the stem and the GPS as one combined unit, onto the windshield connector. I had more breathing room when I first attached the stem back to the windshield, then put the GPS on the stem, then lightly tightened the plastic collar.

I am sure we will get this perfected between the two of us. I am super pleased with the size of the GPS. Anything smaller becomes a reading glasses issue for my old eyes. With this one my distance focus for the road and the GPS is the same and I can quickly switch between the two. I bet folks with better sight also spend less effort looking back and forth. Probably safer than a smaller unit for all.
 

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I was thinking, maybe what triggers the GPS to turn on even though it is hooked up to an always on 12V source is the voltage drop when the dome lights turn on.

When changing the bulbs to LED bulbs I noticed the dome light has a pair of power diodes installed. Only reason for this is to prevent a power surge usually caused by a relay opening. When a relay opens (turning off power) a magnetic field collapses causing a reverse surge of power. The diodes shunt this reverse surge to ground right away.

I am heading out there with my DVM (digital volt meter) and checking things out now. A diode across the power leads for the GPS might also resolve the issue. I'll be back later with my findings.

The two wire connector is for the microphone.
 

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So I tied into the black and red wire of the three wire connector. With the LED bulbs installed, the GPS unit did not power itself on, with the stock bulbs it did power itself on. So it is as I suspected the higher wattage drawing bulbs causes a voltage drop just enough to fool the GPS unit thinking you just plugged it in.

Now I didn't cut the cigarette lighter end off the power cord, I spliced in a socket on the wires plugged the power cord into the socket and taped them together to prevent vibration from allowing them to come loose. Tucked the socket and extra wire up inside the head liner and all is good.
 

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Well I stand corrected sort of. Even with the LED dome light bulbs, when I unlock the truck and open the doors the GPS does self power on. But not all the time, just the first time after the truck sits for some time. When I turn the truck off and head into a job, then come back out the GPS doesn't power on (usual time on job 1.5 hours). When I first unlock the truck in the morning the GPS does self power.

So I'm thinking there is a slight voltage drop on the battery charge as it sits for a period of time, and when the power door locks along with the dome lights turning on causes just enough of a voltage drop and spikes back up to cause the GPS think it was just plugged into a power source. The solution to this which I will test out soon is to install a capacitor across the power leads that feeds the GPS unit. So when the voltage does drop the capacitor will make the drop a lot less significant.
 

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Heads up, DO NOT connect to the dome light power wires. Some how the 10 amp fuse blew on me. There is some sort of seepage current on the dome light circuit. I wired the power socket I am using for the GPS unit to my auxiliary battery. When looking for the fuse that blew, I used a volt meter to check the voltage on both sides of the fuses in the panel by the driver's left knee. The blow fuse would register 12V on the live side and 0V on the blown side. But I was reading 2.3 Volts on the blown side. I did notice the fuse was not 100% open either when you use an ohm meter to check a blown fuse you would read infinite ohms, a good fuse will read 0 ohms, the blown fuse in this case was reading 2.8 mega ohms which could of gave me a bit of a seepage voltage enough to power LED lights and make me scratch my head a while.

One thing I did notice is the LED lights in the dome light are very faintly lit up when the van auto turns them off. If I move the dome light switch from auto to off they turn off 100%. I have not checked the lights in the cargo area yet. I figured I mention this in case you happen to notice a parasitic load draining your battery with the van not running, check the dome light fixture.
 
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