2003 E55 AMG MOST LOOP OPEN
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Newbie
Joined: Jan 2026
Posts: 2
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From: New Zealand
2003 E55 AMG
2003 E55 AMG MOST LOOP OPEN
I have recently bought a 2003 E55 and the radio has not been working since I bought it. The radio turns on and shows AMG logo but then turns off, I checked the codes and did some research and the Fibre optic loop is open but I cant find which part is causing the problem. I bought a Fibre optic bypass plug and have tested it in the CD changer, and the Navigation unit in the left side of the boot and none has fixed it. Im not sure the order in which the light goes through but i know that the light goes through the Head unit, CD changer and Navigation system. Im not sure what to check next.
When I first took the head unit out I accidentally pulled the wire out of the green connector which i'm not sure is necessary to fix because its not fibre optic
Also the previous owner had a Bluetooth adapter not sure if it was Mr12Volt or different brand but the power/ground wires were left disconnected and have corrosion on the end of the plug and the Fibre optic for the Adapter was left hanging which i plugged back into the CD changer.
Should I be disconnecting the battery and resetting it after checking each Component or would it not matter.
The codes I have are:
D100: Most Master reports open ring.
D117: Specified/ Actual configuration of Most ring differs.
I have access to a scan tool if that could help me locate which part is faulting.
When I first took the head unit out I accidentally pulled the wire out of the green connector which i'm not sure is necessary to fix because its not fibre optic
Also the previous owner had a Bluetooth adapter not sure if it was Mr12Volt or different brand but the power/ground wires were left disconnected and have corrosion on the end of the plug and the Fibre optic for the Adapter was left hanging which i plugged back into the CD changer.
Should I be disconnecting the battery and resetting it after checking each Component or would it not matter.
The codes I have are:
D100: Most Master reports open ring.
D117: Specified/ Actual configuration of Most ring differs.
I have access to a scan tool if that could help me locate which part is faulting.
Thread Starter
Newbie
Joined: Jan 2026
Posts: 2
Likes: 0
From: New Zealand
2003 E55 AMG
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Joined: Jan 2014
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From: Republic of Texas
'99 and '05 E55 AMG
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