Can you wire a GPS unit into the Mercedes loom?

[amwebby]

When I purchased my CL500 the first thing I discovered was that my Tom Tom Go would not work inside the car. I assume there is some metallic substance in the heating element or the window tint, that interferes with the inbuilt GPS aerial of the GPS unit but it just goes crazy.

I've got used to the Mercedes system but miss the speed camera function and wondered if it is possible to wire a Road Angel or similar into the Mercedes' GPS aerial? I know you can fit external aerials but I'm looking for as unobtrusive an installation as possible.

 

[miro]

When I purchased my CL500 the first thing I discovered was that my Tom Tom Go would not work inside the car. I assume there is some metallic substance in the heating element or the window tint, that interferes with the inbuilt GPS aerial of the GPS unit but it just goes crazy.

I've got used to the Mercedes system but miss the speed camera function and wondered if it is possible to wire a Road Angel or similar into the Mercedes' GPS aerial? I know you can fit external aerials but I'm looking for as unobtrusive an installation as possible.

You need to buy a unit which accepts speed signal and GPS input and sits in a cradle. They are surprisingly hard to find given that the idea is not new. You may want to consider buying the official TomTom or NavMan sold by Mercedes to A-Class owners. It sits above the air-vent and has all of the necesaary wiring as inidicated. Still will need some mods to fit in your car.

I need to validate the GPS and speed function ... not sure 100%.

 

[sstylos]

You can use GPS signal repeaters too. It takes the signal outside the car and transmit it inside. But I don't beleive this is cost effective

 

[miro]

You can use GPS signal repeaters too. It takes the signal outside the car and transmit it inside. But I don't beleive this is cost effective

There is no fundamental problem getting the OEM splitter and cables to work.

The issue is that most of the smaller GPS units do not have a data port. Im short on time but I recall that the Mercedes bundle for W169 (small dash mount unit) is able to accept a speed signal.

 

[BTB 500]

When I purchased my CL500 the first thing I discovered was that my Tom Tom Go would not work inside the car. I assume there is some metallic substance in the heating element or the window tint, that interferes with the inbuilt GPS aerial of the GPS unit but it just goes crazy.

That sounds a bit weird .. my Sharan has a tinted and electrically heated windscreen, and the Tom Tom (910) works fine in there.

Edit - I've applied a number of TT software releases, some of which have included new GPS chipset firmware to improve reception. Not sure what the situation is with the TTG, but I would definitely check you have the latest software on it .. just in case.

 

[fuzzer]

That sounds a bit weird .. my Sharan has a tinted and electrically heated windscreen, and the Tom Tom (910) works fine in there.

Edit - I've applied a number of TT software releases, some of which have included new GPS chipset firmware to improve reception. Not sure what the situation is with the TTG, but I would definitely check you have the latest software on it .. just in case.

but , i would imagine amwebby has imfrared protection glass which has a metallic film in it which screws with gps and radar detectors.

 

[BTB 500]

but , i would imagine amwebby has imfrared protection glass which has a metallic film in it which screws with gps and radar detectors.

Yup I'm sure that's it, however my Sharan screen has a wire mesh in it (for the heating) which is supposed to block GPS too.

The later Tom Toms do have a different GPS chipset, meant to be much better at picking up a signal. If amwebby knows anyone with a later TT he could try in his car, a newer Tom Tom could be the cheapest option!

 

[amwebby]

Another colleague of mentioned the infrared screen having a metallic film which interferes with all GPS units. Now I have two questions;

1. What is the infrared screen for?

2. Which unit accepts the speed signal and GPS input and how do I go about fitting such a beast?

 

[miro]

Another colleague of mentioned the infrared screen having a metallic film which interferes with all GPS units. Now I have two questions;

1. What is the infrared screen for?

2. Which unit accepts the speed signal and GPS input and how do I go about fitting such a beast?

1. Its better

2. I checked the Mercedes unit and apparently it only takes TMC and power.

 

[miro]

If you run the additional data lines up to the mirror via the A-pillar then you can put your LCD near the rear view mirror.

 

[amwebby]

1. Why is it better?

2. I'm not technically proficient enough to hook up TMC and power from the Mercedes loom to a Mercedes TomTom or Navman but I guess my local dealer can do it. I really wanted something that just did speed cameras though.

 

[Diesel Benz]

Yup I'm sure that's it, however my Sharan screen has a wire mesh in it (for the heating) which is supposed to block GPS too.

Are the heating wires parallel wires, perhaps vertically positioned on the windscreen or do they make a net with a small eye size? RF signal attenuation for a specific radio frequency is proportional to the largest dimension of the eye in the metal net. Parallel lines introduce a large eye in one dimension, meaning that this kind of a net would only attenuate very low frequency signals, perhaps UHF range. If the wires are connected to a net with a very small eye, then they should attenuate GPS and cellular phone signals a lot.

W221 at least has an opening in the RF/IR shield in the middle of the windscreen, a small area at the bottom and a small area at the top. Perhaps the top part is not suitable for the Tom-Tom, depending on the GPS antenna location on the Tom-Tom, the lower opening may be too low, if there is one on a CL to start with (owner's manual should tell).

I don't understand why the device needs a speed signal connected. My handy Navigator application with a BT GPS gives speed camera warnings, the GPS device itself gives an accurate speed signal (doppler based).

The IR glasses are for both heat and noise insulation.

 

[Dieselman]

1. Why is it better?

It's to keep the interior of the car cooler due to less radiation pass ing through the glass.

The metallised coating will be a much more efficient block than wires as it is a full coating, the wires leave plenty of gaps.

Also your CL has double glazed side windows and probably thicker windscreen than most cars for sound deadening.

 

[mw_C32]

I had a Vivaro with this kind of windscreen and my sat nav/ b2 would not work through it either. So I got a re-radiating aierial for about £50.00 similar to this but search google.....http://www.semsons.com/gpsreran.html

It does not connect to your kit directly but you can get a lock on to satelites from this.

I put the outside bit (magnetic) on the roof and the wired bit throught the door lining to inside the car..

Not the best solution but it did work.

Mark.

 

[BTB 500]

Are the heating wires parallel wires, perhaps vertically positioned on the windscreen or do they make a net with a small eye size?

They're vertical, but zigzag rather than straight.

 

[miro]

........I really wanted something that just did speed cameras though.(

We have that system in Australia and it works in every car. We call it "driver".

 

[amwebby]

You obviously don't have as many speed cameras as we do, often sited where they are designed to catch the unwary, at the bottom of declines and so forth.

In addition they are often situated on a stretch of dual carriageway where the speed limit will vary from 30 -40 - 50 and back again for no apparent reason.

Driving under such circumstances becomes tiring and downright dangerous as you are constantly looking for the tell tale white marks on the road and trying to discern if the yellow box on the side of the road is a camera or a traffic sign instead of concentrating on the traffic.

 

[miro]

You obviously don't have as many speed cameras as we do, often sited where they are designed to catch the unwary, at the bottom of declines and so forth.

In addition they are often situated on stretch of dual carrigaeway where the speed limit will vary from 30 -4 - 50 and back again for no apparent reason.

Driving under such circumstances becomes tirinbg and downright dangerous as you are constantly looking for the tell tale white marks on the road and trying to discern if the yellow box on the side of the road is a camera or a traffic sign instead of concentrating on the traffic.

As I only have a C180 the inherent problem is never acceleration. Perhaps slowing down is something else.

When I am very tired I just set my speed to whatever the lowest speed on the highway is and leave it limited to that speed. Im quite happy to sit on 70 if the road is 80 most of the time and 70 the rest of the time.

That is what the speed limiter is for after all. To me that is one of the best parts of my car and its design.

 

[Diesel Benz]

They're vertical, but zigzag rather than straight.

Thanks for the detail, for radio attenuation it does not matter if they are straight or zigzag as long as the vertical lines do not touch each other (except at the bottom and top of the windshield of course).

 

[amwebby]

As I only have a C180 the inherent problem is never acceleration. Perhaps slowing down is something else.

When I am very tired I just set my speed to whatever the lowest speed on the highway is and leave it limited to that speed. Im quite happy to sit on 70 if the road is 80 most of the time and 70 the rest of the time.

That is what the speed limiter is for after all. To me that is one of the best parts of my car and its design.

Agreed, and I use the limiter or the cruise control regularly when going over SPECS sections. However, for the A13 (to name but one) where the speed limit goes from 70 to 50 to 40 to 30 to 40 to 50 and then back to 30 when entering London, the cruise control and/or speed limiter is just plain useless.

Be grateful the Australian government hasn't woken up to the revenue to be generated from speed cameras by adopting such tactics. It is so endemic insurance companies don't count speeding points against you at renewal time any more.