Third brake light fault on a 2013 E Class coupe

Robert Cairns

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E Class Coupe Auto 2013 220CDI
I have an issue with the 3rd brake on the boot lid not working. I have checked and have found the LED light assembly is functional but there is no voltage reaching it. The other brake lights are working OK so it looks like a break in wiring. Does anyone have an electrical schematic for the brake lights or know if there are any relays for the 3rd brake light only.

Regards
Bob Cairns
 

rpalmeida

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Its wired to the rear SAM. To connector 6HD pin 1, Black/Red 0.5mm

It goes via an intermediate connector somewhere between the back window and the SAM, so you could check the wiring ?

Cheers
Richard
 

LostKiwi

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'93 500SL-32, '01 W210 Estate E240 (RIP), 02 R230 SL500, 04 Smart Roadster Coupe, 11 R350CDi
Most likely cause is a break in the cable where it twists at the boot hinge.
 
OP
R

Robert Cairns

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E Class Coupe Auto 2013 220CDI
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Hi Guys
Thanks for the info. I found the fault in the wiring loom. 4 broken wires where they flex coming from the boot lid hinge to the Sam unit on the r/h side of the boot. Seems like this is a common problem, even though the Mercedes dealer to went to for wiring diagrams denied this. In fairness to them they did print out and give me the wiring diagrams for rear lights, which in truth I did not expect them to.

Regards
Bob Cairns
 

Davyp82

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Eclass Coupe
Hi Guys
Thanks for the info. I found the fault in the wiring loom. 4 broken wires where they flex coming from the boot lid hinge to the Sam unit on the r/h side of the boot. Seems like this is a common problem, even though the Mercedes dealer to went to for wiring diagrams denied this. In fairness to them they did print out and give me the wiring diagrams for rear lights, which in truth I did not expect them to.

Regards
Bob Cairns
Hi Bob
Bit of a long shot here but I think I may have the same issue. Both the 3rd brake light and right number plate light have stopped working at the same time. My feeling is this is likely a wiring issue. Is this something you could explain (in simple terms). Local dealer has suggested £500+ to fix that seems excessive.
Thanks
David
 

EmilysDad

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ML350
Hi Bob
Bit of a long shot here but I think I may have the same issue. Both the 3rd brake light and right number plate light have stopped working at the same time. My feeling is this is likely a wiring issue. Is this something you could explain (in simple terms). Local dealer has suggested £500+ to fix that seems excessive.
Thanks
David
Welcome to the forum.
I'm sorry, but can't suggest any practical solution other than to find yourself a reputable auto spark and get a quote/suggestion from there.
The dealer is taking the proverbial.
 

mioba

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W124/E200, W220/S320CDI, W205/C200, W251/R350CDI 4Matic
The dealer will no doubt change that loom which will require panelling to be removed so dealer labour costs.
An auto electrician will probably solder up the offending wires
 


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