dw1

I bought a used MCS (BB0511, A2038701189) COMAND built in 2005 and installed it in my 2007 C230.

The nav never showed any number for satellite signals received, so I suspect a bad GPS antenna.

The unit has not yet been "encoded" by an SDS so that the instrument cluster shows nav data because of this problem.

The antenna sold to me with the unit is a generic blue-connector FAKRA one, I think. It is labeled "GPS Antenna G-503".

A few questions to the gurus on post-facelift W203 US COMAND:

- Is the only way to tell if the antenna is bad by getting another antenna?

- Does the fact that I measure 0.005 ohms between the center and shield of the FAKRA GPS antenna connector mean anything?

(Well, I know it means the antenna wire isn't broken, but I don't know what resistance this is supposed to be.)

- What is the correct antenna for this unit?

(I've seen a lot of posts on this, but many reference APS units, not MCS-II, and/or have links to long-expired eBay items).

Thanks

Moviela

I think you have a very sensitive meter there. I need a labratory instrument with a special four wire probe to measure .005 ohms. I think you might be reading .005K ohms, or 5 ohms. This is near a short on the antenna line. It might have been pinched or cut to make it read that low. Usual passive antenna reading is infinite. The shield should be just that, a screen to prevent signal pick-up by the antenna lead. The oem antenna is mounted on the rear of the car, but for after sale installation the factory suggests the antenna be laid on top of the instrument cluster, under the dash pad. It would be a waste of time to yank out the interior of the car to install an antenna in the rear.

You can use the EPC to find the correct replacement antenna for your car.

dw1

Thanks for the input. Yes, I mis-wrote the resistance reading. It reads 000.5 to 000.7 ohm. The meter is a standard Fluke 87 for which a reading of 0.2 - 0.3 ohm is a short. So I'm probably reading just a bit of the antenna lead wire and the short-circuit.

The information that a passive antenna should read a very high resistance value (infinite or close to it, depending on the meter) is a very valuable input - thanks.

Fyi, I checked my copy of the EPC and all I get is the OEM rear-mounted GPS/Telaid antenna, and I'm interested in an under dash-mount retrofit one that is confirmed compatible with the MCS-II Comand units (OEM pn? Is it the same as the APS one?) or an aftermarket one that will definitely work with my MCS-II.

Oh, and your signature line mentions "no snickering" - Hey, member "jrthiele" showed us how good a W203 wagon can look with a CL-type grille awhile ago (11/27/07)!

dw1

OK, I've got the GPS function working. The cheap generic GPS antenna had multiple breaks in the inner insulator. I spliced in a piece of coax cable.

Probably because the prev. owner had the antenna wire in a place where it was baked by the sun, the wire insulation was very fragile.

This generic antenna doesn't like going under the dash top - # of satellites goes down.

Can anyone tell me if the M-B retrofit part, M-B part number 67823100 (which supersedes 2038200975), has a FAKRA connector, or needs a connector adapter?

ChrisBrown

I purchased a "generic" from eBay when I installed my MCS-II COMAND unit. I actually placed it to the right, under the dash but on top of the glove box. I haven't lost any satellites and reception has been fine.

samaritrey

Yeah generic one would be best the oem one is very expensive