W203 Coupe Audio 10 Poor FM Reception

Discussion in 'Electronics' started by Solaris002, Apr 5, 2014.

  1. Solaris002

    Solaris002 New Member

    Feb 10, 2014
    C180K Coupe (CL203)
    Hi All,

    I have seen a lot of threads on this topic but not one that fits my issue exactly...if my search skills have let me down...apologies in advance.

    My C180K Sports Coupe (52 Plate) has poor FM radio reception.

    I don't have a weak Central Locking radio signal issue and can lock/unlock the car from Space! (most threads seem to have a poor FM + central locking issue together and can only lock/unlock using IR sensor)

    I have checked Fuse #8 (7.5A) on rear SAM unit, which is good (saw this mentioned in one of the threads).

    I have checked the rear windscreen and to the best of my eyesight, cant see any broken/burnt wires.

    I removed the left (n/s) boot lid trim (the one covering the electrical connections for heated windscreen, radio amp, etc)

    I removed the trim hiding the thin amplifier units in the boot lid (destroyed most of the tabs securing it to the boot lid in the process...*******o!)

    Question 1: How do I now fault find where the issue is? People may be quick to say...the rectangular amp units are faulty in the boot lid. How can I test this with a multimeter and know for sure?

    Question 2: On the left side of the boot lid, I can see a white connector type thing. I stuck my multimeter across the black and red wire and got nothing. Does this mean there is an issue with no juice running up there (i.e to the FM amp units...therefore suggesting i need to confirm current passing between rear SAM and that connector in the boot lid)? Having said that, if my Central locking radio signal is perfect, does this eliminate the thin amplifiers units in the boot lid as culprits?

    Question 3: Can someone tell me what values (Volts/ohms) I should be able to read at relevant/apropriate test points to help narrow down my issue?

    Question 4: The car has a panoramic roof so no option for a shark fin aftermarket aerial. Any other options if I get no where with this?

    One interesting observation...if I stick my finger on one of the windscreen elements at the top of the windscreen (basically the bit where the glass is closest to the thin amplifier unit, the FM signal gets a boost. Relevant?!? or just my electric personality :))

    Also, the N/S wheel arch liner (which hids the washer bottle etc) is missing and I can see couple of wires. Anything down there that may be worth investigating?

    Thanks for reading and any advice.

    Cheers all.

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