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1993 300E, 1995 E320
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Discussion Starter #1
New to me 1993 300E

My situation and am I correct or incorrect to suspect the light switch?

Parking lights work.
headlights work, both low and high beams.
Directionals work.
Brake lights work.
hazards work.

No front fog lights.
No rear fog lights.
No rear left or right standing lamps.

Bulb out indicator in instrument cluster comes on when lights are turned on.

The bulbs in the front fogs are new.
I have upgraded all the fuses.
 

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W124 Moderator
86 190E 2.3L 16V, 2 95 320TE's, 02 S500
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12,667 Posts
New to me 1993 300E

My situation and am I correct or incorrect to suspect the light switch?

Parking lights work.
headlights work, both low and high beams.
Directionals work.
Brake lights work.
hazards work.

No front fog lights.
No rear fog lights.
No rear left or right standing lamps.

Bulb out indicator in instrument cluster comes on when lights are turned on.

The bulbs in the front fogs are new.
I have upgraded all the fuses.
I would start off by replacing the bulbs that are burned out.

Sent from my XT1080 using Tapatalk
 

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'95 E300 DIESEL, '91 600SEL, '92 600SEL
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17,048 Posts
^This. And only using Osram/Sylvania/Philips. No Chinese milli vanilli junk if you want to keep the bulb out warning light at bay.
 

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1993 300E, 1995 E320
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1,084 Posts
Discussion Starter #5
I agree on using only top quality bulbs.

Would a bad relay cause ALL the lights not to work and not just the fogs?
 

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04 odyssey (265k) 1995 E320 wagon (295k)
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2,903 Posts
The "relay" is a box with either 3 or 4 relays inside. So yeah its possible the Fog relay died inside the relay box.
Not sure what each relay controls, but there definitely is multiple relays inside the "lighting relay"
 

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1994 SL320
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1,825 Posts
I agree on using only top quality bulbs.

Would a bad relay cause ALL the lights not to work and not just the fogs?
You have an ECU controlling everything.

I'd check power @ the relevant fuses then work either upstream or downstream.

I'd suspect either the switch or ECU, but wouldn't swap anything until I'd proven it. A wiring and ecu pin diagram would make life easier.
 

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'95 E300 DIESEL, '91 600SEL, '92 600SEL
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17,048 Posts
You have an ECU controlling everything.

....
Come on now, let's call it for what it really is . . . a multifunction relay.

The W124s lighting system is as dumb as an ox compared to newer MBs with programmable SAM modules and the like.
 

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1995 E320 sedan, 1991 Porsche 964, 2004 Porsche 986
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450 Posts
How janky does your switch feel? Mine lost the detents not too long after I got it, so there is a potential that the switch is faulty - especially if it's original.
 

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1993 300E, 1995 E320
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1,084 Posts
Discussion Starter #11
This is what I found in the relay box. Which is the fog light?
 

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1993 300E, 1995 E320
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Discussion Starter #13
Thanks.
 

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Premium Member
2003 G500, 2000 SL500, 1995 E320 Cabriolet, 1980 TR8
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1,042 Posts
Just for the sake of completeness, the "exterior lamp failure monitoring module" (the long one on the right of the relay box) is not actually a relay, but rather is a series of resistive current "shunts" coupled to a a single chip logic circuit that senses the current draw for various exterior lighting. Current switching for the exterior lighting circuits is handled by the switchgear itself (e.g., the headlight switch, the combination stalk, etc.), not this module unlike the more advanced "SAM" modules found in later cars. There are no internal contacts to fail like a traditional relay (or a SAM for that matter), although it is possible for the resistive shunts to "blow" open and fail which will cause an open circuit and therefore failure in the sensed lighting circuit. It has been my observation that when one of the shunts fails in the exterior lamp failure monitoring module it will cause the light-out warning light to come on even when the bulbs are all good which might be an issue here.

For what it's worth, I am curious what you are referring to when you say "standing lamps" - are you referring to the far counter clockwise headlight switch positions that lets you activate just the left or right parking lights? If you are, the current for that function passes through the same shunts in the exterior lamp failure monitoring module as the parking lights so this would point away from the exterior lamp failure monitoring module as the cause for their lack of functioning and more toward the headlight switch. Add in the fog lamp issue (a separate set of contacts in the headlamp switch) and I would say almost definitely the switch has problems.
 

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1993 300E, 1995 E320
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Discussion Starter #16
Standing lamps meaning the rear left and right parking lamp.

I am now thinking a bad ground or short somewhere??? With no lights on, and when I step on the brake pedal the switch backlights to the window switches, seat memory, defroster, rear passenger light, headrest lowering switch, shifter surround lights blink on and off rapidly until I let off the brake pedal.

The other issue is I got the rear standing lamps to work but, still no front fogs. Also, two of the bulbs in the passenger's rear taillight were significantly dimmer than the corresponding bulbs on the driver's side.

After fiddling (technical term) with the rear lights my car will no longer start. I tested the OVP relay and think that is now bad. Ordered a new one.

The main eco junk harness and throttle body have been updated. The battery/starter/alternator (lower harness) has not.

Suggestions?
 

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04 odyssey (265k) 1995 E320 wagon (295k)
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Did you disturb the lower harness at all? If so you may have an exposed wire. You can pull, and wrap (self fusing silicone tape) the harness or replace to correct.
And Thanks flooby, always there to help explain the world of the electron.
 

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1993 300E, 1995 E320
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Discussion Starter #18
I don't THINK I disturbed the harness as I haven't been near it. Would the lower harness cause issues with fog lights? I know it has not been replaced so maybe time to do that regardless.
 

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W124 Moderator
86 190E 2.3L 16V, 2 95 320TE's, 02 S500
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12,667 Posts
I don't THINK I disturbed the harness as I haven't been near it. Would the lower harness cause issues with fog lights? I know it has not been replaced so maybe time to do that regardless.
No, the lower harness has no play with the headlamps. As mentioned, I would replace the switch. If you use the search function, you'll see a considerable amount of post regarding very similar issues as yours.

Good luck

Jayare

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1993 300E, 1995 E320
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1,084 Posts
Discussion Starter #20 (Edited)
I pulled the starter harness today and will rewire it. This is very simple other than I have to pick up a new connector for the oil level sensor.
 
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