SL/R129: Electrical short, Power mirrors, tilt steering. turn signal
Thread Starter
Junior Member
Joined: Mar 2016
Posts: 22
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From: Playa Vista, CA
2015 S550 & 2012 E550 Convertible
Electrical short, Power mirrors, tilt steering. turn signal
There seems to be a short somewhere. The power seats on both doors, rearview mirrors only work when I open a door with the ignition off. When I turn the steering wheel and sometimes the turn signal, the gage meters and lights on the instrument panel flicker. Yesterday, the AC was going on and off. OMG. 1992 300sl. I just changed out the Climate controls, A/C center vents. Re-covered the seats, changed out one seat belt. (every now and then the seatbelt light comes on too). I don't know where to start. The flickering light issue has been going on since before all this whenever I turned on the turn signals, the lights flickered on the instrument panel.
Any suggestions besides driving it off a cliff?
Any suggestions besides driving it off a cliff?
Super Member
Joined: Jul 2010
Posts: 598
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From: Eastern Kansas
94 SL 600, 98 993, 89 XJS Conv., 85 Daimlier Princess 16 Hybrid Lincoln 16 Chevy crewcab
door hinge wiring area would be my guess. easy access with door panel off and footwell carpet panel off. An insulation break is what I would look for with the door swing movement.
MBWorld Fanatic!
Joined: Jun 2011
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From: Cape town
not a merc
Convenient system is not getting power from ignition. Check all fuses first. Then check power supply to relay. The instrument cluster is also faulty that's why it flashes when you use indicators
Thread Starter
Junior Member
Joined: Mar 2016
Posts: 22
Likes: 1
From: Playa Vista, CA
2015 S550 & 2012 E550 Convertible
convenience module?
I will check the wires in the door to make sure the insulation is not wearing off. I have read that is a common issue. With regards to the power not getting to the convenience module, I have checked the fuses, cleaned them all, replaced them all. Next, I will check the power at the convenience module. Additionally, the key in the ignition is kind of loose, could it be possible that I need to replace the ignition switch and key?
MBWorld Fanatic!
Joined: Jun 2011
Posts: 1,494
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From: Cape town
not a merc
If it works consistently with door open only. how can it be door wiring? Read the wiring diagram and you will see how it's designed to function with the door open. In your case it's not working with the ign on.
Thread Starter
Junior Member
Joined: Mar 2016
Posts: 22
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From: Playa Vista, CA
2015 S550 & 2012 E550 Convertible
convenience module?
I already had the door panel off so I just checked the wiring. I didn't think that would be the issue but at this point, I am checking anything, lol. From what I have read, it is most likely a bad convenience module, however, I am hoping that is not the case since they cost an arm and a leg. The convenience module is what allows it to function with the door open (ignition on or off). As soon as I close the door, it doesn't work (ignition on or off) So that is what makes me think it is a bad convenience module. ugh.
MBWorld Fanatic!
Joined: Jun 2011
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From: Cape town
not a merc
Have a look at the diagram. There is a convenient relay that supplies power to the convenience module. That relay will energise if the door is open or if the ignition is switched on. Your problem is either the relay or the ignition supply to it. I think the relay is inside the fuse box. It was white in colour on a W124. Could be the same colour. Good luck
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Thread Starter
Junior Member
Joined: Mar 2016
Posts: 22
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From: Playa Vista, CA
2015 S550 & 2012 E550 Convertible
convenience module?
Thanks Russell, I will see if I can find the wiring diagram for it and try to locate the relay. I sure hope that is the case. Probably much cheaper than the module.
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Thread Starter
Junior Member
Joined: Mar 2016
Posts: 22
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From: Playa Vista, CA
2015 S550 & 2012 E550 Convertible
Well that would explain why some of the soft top equipment is not working properly. The hydraulics above the windshield unlatch and latch, the soft top cover will latch and unlatch but it will not raise or lower the soft top. Also, the cigarette lighter is not functioning. I heard that was also on that same relay. So, basically, everything that is on the #12 fuse does not work even though, I get power on both ends of the fuse connections with the fuse installed.
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