FM Transmitter strength fix

From the Where To? screen, press Audio and change the audio output setting from Internal Speaker to FM Transmitter.

Turned on FM transmitter fine.. Volume // audio --select FM

Then... Tried to get into diags. (Pressing on battery icon)... Unable to get to diags with:
Antenna down or up Local power press on battery icon

Antenna up with transmitter attached... Local power press on battery icon
Antenna up with transmitter attached... plugged into car... and pressing on battery icon

???

Actually on my 765T I have to go from the menu screen to volume-audio output.

It's not the battery icon -- it's the clock!!!

From the "Where to" screen, press the clock display... for 5 seconds

When I got to the FM Power screen...
The selections I see are:
2.0mW
1.0mW
0.5mW
and a box labeled HIGH POWER, which is checked!!

So I guess I'm there already

Anybody good at converting mW to db?

Above is for Nuvi 660 with V4.7 firmware

???

more later
MODS.. please delete my prior post...

JanJ, I also have a Nuvi 660, I will give your directions a try to see if works. Thanks for the good information.

I looked at mine (765T) and it was at 105 db. Changes would not stick; although, when I tried to exit from diagnostic mode, it would hang--requiring a power cycle--or reset. Either way, the power setting went back to 105 db.

I find it interesting that Alan's was at 107 and mine was 105. I think this has to do with whether one manually tunes the FM transmitter or uses Autotune. I noticed while using manual tune, not far from Denver btw, that I couldn't get a good signal from the 765T. Once I started using Autotune, the FM signal would almost always come in pretty good. The couple times it didn't, I just did another Autotune and it worked.

I have to wonder if Autotune also adjusts power based on detected noise. That would explain the different [default] levels between Jeff (OP), Alan and myself.

I just always use Autotune now. On a recent trip from Denver to Las Vegas, it worked (although it took two tries, twice, to get it to work).

Thanks for the info; however it does not appear to work on the 680. Although there are three power options (.5mW, 1.0mW, & 2.0mW), by default the output Power on the 680 appears to always reset to High Power option.

You must have the same options I posted about on my 660..

Question... What is "High Power" ???

Mine always reports as "High Power"

not working on mine, tried about 20 times. version 3.90 765T

Followed directions stroke for stroke and just will not stick on my 765T either.

Just as an update- I've power-cycled the unit multiple times, drained the battery all the way and recharged, even ran a couple of software updates.

The increased db output has stuck for me ever since, and I've been enjoying my FM transmitter ever since I made the OP. The only setting that will NOT stick is the 'high output' setting which seems to revert to 'off' after I exit the diagnostics area.

I have no explanation as to why it would be sticking with some of us, but not others.

If anything changes I'll post about it here,
Jeff

Good news, I'll try this on my Nuvi 660 tomorrow. If it doesn't work, I'll stick to my 1/8" plug

I use a Scosche FM modulator that injects the signal directly into the radio antenna jack. Works absolutely great. It does not effect normal radio reception. It cost $35 at Amazon.com with free shipping. On my Chrysler minivan the antenna cable connection is available behind the glove box door. Total time for installation was less than 30 minutes.

ill need to try this on my 765 great find!

I tried it on my 765 unit but no luck. Afer reboot it goes back to 106 DB.

If your GPS won't hold a higher transmitter power setting, why not get some thin wire, strip the insulation off about 4 inches, and wrap the bare wire around the end of the antenna plug nearest the cable on the antenna lead for your car radio, and thread the wire up to the top of the dashboard?

Those with technical skills can solder the wire, but I doubt that soldering is mission-critical in this specific case.

From there, you can run the wire down along the joint between the back of the dashboard at bottom of the windshield.

The transmitter power can be very low if the antenna is very close, so adding the wire should make a significant and permanent difference in the ability of the GPS to be picked up by your radio.

My GPS only speaks through an internal speaker, so I cannot offer photos or anything other than general advice in this area, but I do have a PhD in electrical engineering, and know a bit about antennas and such.

It seems the basic problem is that the radio antenna for the car stereo is outside the car. Even with tweaks to the signal strength, the output is weak at best. The solution might be to bring the connection inside the car. Three are three approaches I can think of:
1. Connect the nuvi directly to the car stereo using the Aux input as per Keith. This works fine.
2. Connect another device (such as an MP3 player) with FM capabilities to the car stereo with Aux connection and tune to the nuvi frequency. This actually seems to produce better sound for some reason, particularly when I am playing mp3 files on the nuvi (I have a nuvi 755t). Because it is inside the car and close, there are fewer signal strength problems (based on my limited testing).
3. One problem with the above solutions is that they monopolize the car stereo. For example, I have subscription music services that are not compatible with the nuvi mp3 player. So one wild solution I am contemplating is getting a cheap portable FM receiver with speakers that I can set up close to the nuvi. This way, I can play whatever I want on the stereo, but the nuvi will still be able to prompt me with announcements. I lose the nuvi's ability to pause the playing of other media, but gain the ability to use other media devices. Whether this will solve the signal strength problem remains to be seen, but my experience with an in-car media player suggests it will. If anyone has tried this, let me know.

I have 765t and tried it several times and after restart it allways go back to 107db instead holding to 115db so, conclusion is...either my or your 765t is defective, or you've done more than before...just for sake of curiosity would you check what it shows now? Iam sure it will show 107db instead of 115db. Tx.

I also tried this on the 765T but it did not hold.

Altho9ugh I am not having too much trouble with the FM signal (no hissing or crackle), the volume is way low on the radio with the 765T.

I definitely notice FM static until I turn on the FM Power checkbox. If anyone has an idea of how to save this setting that would be great. I'm wondering if you can edit the XML file or the like on the unit.

Thank goodness I now have a car that has the connection for mp3 players. The FM transmitter in the Garmin and probably any other mfg. is totally useless and more trouble than it is worth.

Thanks for sharing, I was very annoyed with the transmitter until now!

I can't wait to try it out.

Nuvi 775T
I got mine to stick at 115db! The trick is go indoors where you can't get a sat signal. Then do a clear user data
* hold finger on lower right of screen
* while holding turn on
* keep finger on screen until it asks you if you want to overright user data
* make sure your data is backed up if you don't want to lose anything.
* click yes and when it boots up make sure you use "United Kingdom" as a locale. I think this overwrites the FCC regulation. Of course the language will default to Brit.
* Go into volume and select FM transmitter and select a station. Go back twice.
* Go into the maintenance screen by holding battery
* Change to FM power and boost the DB level to 115. DO NOT click the FM power checkbox or it may not take.
* Go back 4 times and exit.
* Check the Nuvi on your radio. If you don't hear anything do a software reset by holding the power button to the left for 8 seconds until it reboots. I had to do this.
* You will know if this is working because initially when the Nuvi boots up you will hear the tone it makes on your FM radio with the usual hissing on the FM channel. Then it will load maps. when it's almost done loading the maps you will hear the FM power boost click in and the static mostly goes away.
* Try out your fav MP3's now!

before you break the law red this:
http://en.wikipedia.org/wiki/Title_47_CFR_Part_15

This procedure seems to work for my 750 as well. I had to do the reset by holding the power switch to the left for 8 seconds. Also, if I turn off the FM Tx and then power down the 750, it reverts to low power. However turning off the unit with the FM Tx enabled brings it back to full power the next time I turn it on. The only drawback is that it now shows my elevation in meters.

47 CFR 15.209(a) states the maximum permissible power for intentional radiators operating between 88-216 MHz is 150 microvolts/meter measured at a distance of 3 meters from the antenna.

The FM transmitter in a Nuvi is an intentional radiator.

Wikipedia states the maximum is 250 microvolts/meter.

Maybe BobDee can convert microvolts/meter to db's for us...

The only thing I might worry about is someone on the freeway tuning the radio, and hearing Jill say, "Turn right in 500 ft on Jensen Ave". That'd mess them up a bit! LMAO!

It amazes me how lazy people can be, wanting me to do his conversions. Juggernaut That's not gonna happen.
Instead I will give you a conversion chart so you can do it yourself.

http://www.moseleysb.com/mb/mv2dbm.html

Umm.. Part 15 address jill's cross talk between cars!
which is very annoying, but obviously you don't care about anyone but yourself. Because I could care less that you have to "Turn right in 500 ft on Jensen Ave".

Yes your welcome Update: I did another reset and re-selected my locale, changed the volume back to FM transmitter, held the battery icon down and went into the maintenance screen and the setting stayed at 115db!

Do you think this applies to the 885T, as well?

If I'm transmitting to my FM @ 88.9 frequency, will the person in the car along side of me hear my GPS if they are not tuned to 88.9?

The reason I ask is, can this be that much of an interference issue? What's the chances another person would have their FM tuned to a dead frequency location I may have chosen to transmit to?

Not really. Try holding the GPS and move away from your car. You will see that it soon statics out. I have a 12v plug in transmitter I bought at dealextreme in HK that works very well. In fact I can walk around the house with a radio and the thing transmits that far. The GPS even with the power set up all the way is not an issue.

The FCC is not very liberal about being able to transmit very far.

Sorry but I was wrong, this doesn't seem to work with my 750. I took a short trip this morning and listened to an audio book. The unit froze up twice on a 20 minute trip in and once on the trip back. Each time the 750 had reset itself to 99 db. I set it to 115 db after I got back home and each time I powered the unit down and back up it had reset to 99 db.

Well sir, I'm not lazy at all, and never have been. I guess you failed to see the humor in my post. That's ok, though.

But, I do thank you for the link to the chart.

I have to give this a try!!!

oblachubs you have indeed found the way using the United Kingdom.

I used this all day on my 765T and it really works. I used the thing just like normal, started and stopped several times, changed destinations, played MP3. I have a Toyota with the antenna in the rear window and never heard any interference all day.

The elevation in meters is the only thing I've noticed different and since the elevation is not very accurate anyway I can live with meters.

I can assure you, unless somone has there car parked on top of yours, they are not going to hear your FM transmitter. Even by raising the power on the Nuvi, it is nowhere near enough power to interfere with another vehicle. On top of that, what are the odds that there will be someone so close to your vehicle that happens to be listening to the same blank frequency that your Nuvi is broadcasting on? I think you would have better odds of winning the lottery than causing interference.

And I will tell you what IS annoying...Having a piece of equipment in your own vehicle that is designed to transmit to your own radio, and it does not have enough power to so so without also hearing static. THAT is annoying.

Good point-

Microvolts per meter is not a db in itself---you must specify a load resistance. Wikipedia has extensive reference material you may find informative.

Thanks for the tip. Will it a try.

The setting does stick on mine. 115db + high output ticked.. It seem to need the sat lock to show settings in the diag menu...
No sat lock it shows 107db, with it 115db...
If it does matter, I'm in Canada...

Cheers,

I followed this procedure exactly. It doesn't work on my 760. The only result was that my unit was set for the UK. The FM power reverted back to 96db.

Sorry it doesn't work for you. Although the 760 is different from the 765 which I was posting for.

Also a word of warning to others:
If you should go back to the volume control and change from the FM transmitter back to the internal speaker and back it will get stuk on 106db. I just ran into that last night. So unless you need to don't change back to internal speaker or you will have to follow my procedure all over again. It's not worth it to me to be playing with this all the time. I'll just use my other FM transmitter and be done with it.

OB

Unsure if this would work with a 660..

But..no matter.

Ever since I installed a some GM9-Aux boxes into two of the firebirds, I havent had to deal with the frustration of the fm xmitter.

So on my 885T the default setting is 102 and it works
pretty well as is, but I can change it to 120 and even power off (remember power-off on 885T is really a stand-by mode) the unit and it will stick unless I change to internal speaker mode or do a reset, in which case it goes back to 102. No special magic or Hocus-Pocus needed.

This reminds of an old Arlo Guthrie song....

"What were you arrested for kid?"
"Adjusting the FM power on my Nuvi"

and they all moved away from me on the bench...

That's about it, huh!

I have an 885T, also, but I can not find a default setting of 102 or anything else. How did you get to the default setting? I had set it to FM output, then pressed on the battery until the test page came up and then I kept going til I got to the audio output test page but can't see a default setting of any kind.

gerrydrake, it works differently on the 8x5 series than it does on other nuvi's. You have to go into the Test Page buttons ... display map, press the speed button, press and hold the speedometer until you get the Test Page menu buttons. Scroll down and you will see the FM transmitter test. This is how you get into the FM transmitter test settings, but I do not use the FM transmitter, so I don't know whether the settings stick or not.