[helleifenbein]

I am adding a set of front fog lights to my w108 250s and am testing the waters of knowledge. I would like to wire them up like they were wired as a dealer option. My owners manual list the stock switch as having the ability and option to activate this accessory. I'm hoping members with knowledge can chime in on the correct wiring to the switch(what lead on the switch?) and what relay they used.
Thanks
Dave

 

[3.5 Tony]

Wiring diagram

I can email you the wiring diagram from my 111-I'm sure it is very similar. PM me with your email. It's too big to attach.

 

[bluenapster]

I can email you the wiring diagram from my 111-I'm sure it is very similar. PM me with your email. It's too big to attach.

Hello Tony:

Would you mind emailing me the fog light wiring diagram as well please. I have a 72 280se 4.5 that I am also going to install front fog lights to.

I have purchased new headlights with triangle lights wired as well as a set of older Bosch fog lights. From my understanding if you pull the light switch then the fog lights will turn on.

Let me know and I will PM you my email.

Thanks,
Kal

 

[Climbernyc]

Blue, I'm doing exactly the same. There is a plug behind the headlights as part of the harness that looks like the female of a phono plug- I've seen the original wires for the stock foglights on eBay and it looks like a male phono jack. From what I've read in the archives, it should be easy to run the single wire from the fogs into that and have the stock switch actuate. However, I'm planning on adding relays for extra brightness and switch longevity

 

[helleifenbein]

I can email you the wiring diagram from my 111-I'm sure it is very similar. PM me with your email. It's too big to attach.

P M Sent

Thanks

 

[bluenapster]

Blue, I'm doing exactly the same. There is a plug behind the headlights as part of the harness that looks like the female of a phono plug- I've seen the original wires for the stock foglights on eBay and it looks like a male phono jack. From what I've read in the archives, it should be easy to run the single wire from the fogs into that and have the stock switch actuate. However, I'm planning on adding relays for extra brightness and switch longevity

Thanks for the info Climbernyc. My mechanic is going to do the foglight work, its a bit beyond my skill. I will pass this onto him.

He is also upgrading the alternator to a 90amp unit which he got from Amazon.

 

[Climbernyc]

That's great but remember the resistance of the old wIrving and switch can destroy the switch. Have him use the switch to activate a relay which turns on the fogs. It will still work the same way as far as the switch goes but will be much safer. What was the stock alternator for a 1972 280se 4.5?

 

[3.5 Tony]

sent

Wiring diagram sent. I scanned it in Hi res from my owner's manual-it is very detailed.

I am adding a set of front fog lights to my w108 250s and am testing the waters of knowledge. I would like to wire them up like they were wired as a dealer option. My owners manual list the stock switch as having the ability and option to activate this accessory. I'm hoping members with knowledge can chime in on the correct wiring to the switch(what lead on the switch?) and what relay they used.
Thanks
Dave

 

[3.5 Tony]

Hey Kal,
Do you still need this? I need your email

Hello Tony:

Would you mind emailing me the fog light wiring diagram as well please. I have a 72 280se 4.5 that I am also going to install front fog lights to.

I have purchased new headlights with triangle lights wired as well as a set of older Bosch fog lights. From my understanding if you pull the light switch then the fog lights will turn on.

Let me know and I will PM you my email.

Thanks,
Kal

 

[helleifenbein]

Thankyou Tony
scanned image was received

As for existing wiring on the w108 250s for 1967 there is nothing that resembles a add on for such as Climbernyc mentions.

The only reference I have for my model is the owners manual that list the stock light switch as having the abillity to turn them on. Maybe other chasis numbers had this. It looks like I will be creating the harness from scratch. I will probably follow the head light harness and source an old bosch relay. My biggest goal is to install something that looks like it belongs to the car.
Always welcome to hear more info
Thanks
Dave

 

[bluenapster]

That's great but remember the resistance of the old wIrving and switch can destroy the switch. Have him use the switch to activate a relay which turns on the fogs. It will still work the same way as far as the switch goes but will be much safer. What was the stock alternator for a 1972 280se 4.5?

Understood, thanks again.

Stock alternator was rated at 55amps.

This is the one my mechanic bought. It is uprated to 90 amps.

Mercedes Alternator 1970 1973 AL72X Generator | eBay

 

[gmatthewb]

NOTE: This isn't an 'exact' match for this problem, but may provide some additional info in your electrical trouble-shooting journey.

I worked as a machinist at small M-Benz garage in the late 80's. I recall that someone came in with late 1960's model (W108 / W109 / W113 or W115) for major job of replacing AC/Heater exchange box assembly. One of their 'minor' complaints was that their combination switch wasn't able to "flash" the brights (by pulling the blinker lever toward the driver). The 'bright' function DID work by pushing the blinker lever away from the driver.

During the course of doing all of the work, we found that ONE of the wire connector pins was not inserted into the connector block (and taped back to the harness with masking tape). The tape looked to be the same type and age as that found on inside of door panels & other areas and didn't look like someone's 'repair' attempt. We did some testing with voltmeter and after inserting the omitted connector pin, the 'flash' function worked.

 

[bluenapster]

Mathew, my W108 came with functioning high beam flash by pulling the blinker lever toward the driver. I think it may have come like that from the factory or "fixed" by one of the previous owners. I know that there are W108's out there that do not have the high beam flash ability and your info will help them.

Thank you for sharing this.

 

[DerFuror]

Factory Wiring for Fog Lights

I'm hoping members with knowledge can chime in on the correct wiring to the switch(what lead on the switch?) and what relay they used.

Years ago, I connected a set of Hella driving lights to my W111’s existing factory wiring harness. The car was not optioned with fog/driving lights, but it was wired-ready from the factory.

The fog/driving lights are actuated by turning right, then pulling out the headlight switch. Sometime within the past decade I upgraded the circuit by adding standard Bosch relays. As previously mentioned, the incorporation of relays into a vintage lighting system provides significant lighting performance & safety aspects.

The first items I purchased after buying my car was its operator manual & factory service manual. Each contains wiring diagrams for the car. I noticed the fog/driving light circuit on a diagram & then confirmed its existence in my car’s wiring harness. I traced the fog/driving light circuit along the main headlight wiring harness from the headlight switch to its termination point along the lower inner fender just behind the left bullet-shaped turn signal (my car’s headlights are standard North American design). I spliced in the new Hella driving light wiring from that point, and then the relay decades later.

Since your car is only 2 years younger than mine, there is a very good chance it is also factory wired for foglights. It will be interesting to see what you discover. Good luck.

 

[helleifenbein]

Years ago, I connected a set of Hella driving lights to my W111’s existing factory wiring harness. The car was not optioned with fog/driving lights, but it was wired-ready from the factory.

The fog/driving lights are actuated by turning right, then pulling out the headlight switch. Sometime within the past decade I upgraded the circuit by adding standard Bosch relays. As previously mentioned, the incorporation of relays into a vintage lighting system provides significant lighting performance & safety aspects.

The first items I purchased after buying my car was its operator manual & factory service manual. Each contains wiring diagrams for the car. I noticed the fog/driving light circuit on a diagram & then confirmed its existence in my car’s wiring harness. I traced the fog/driving light circuit along the main headlight wiring harness from the headlight switch to its termination point along the lower inner fender just behind the left bullet-shaped turn signal (my car’s headlights are standard North American design). I spliced in the new Hella driving light wiring from that point, and then the relay decades later.

Since your car is only 2 years younger than mine, there is a very good chance it is also factory wired for foglights. It will be interesting to see what you discover. Good luck.

That is the exact set up I am trying to achieve, I have seen the wire diagrams in my shop manual(does not list wire colors), I understand how the switch works via my owners manual. Did you have to open up the harness to find the wires? I have viewed the area and I see nothing. I have uploaded a pic of the area in question. What color are the lead wires ?
Thankyou for the info
Dave

 

[Climbernyc]

From one of the archives: If you have stacked, and you pull of the headlights til you see the harness inside the buckets, you should see a spare wire with a funny screw on connector on the end. That is the fog light positive. You can use it on its own, or better yet, use it to trigger a 12V30A relay hooked up to some thicker cable to power the lights.

 

[ejboyd5]

By chance, I just came upon this information on the headlight flashing function in Volume Number 8 (May, 1994) of The MERCEDES Collector in a Q&A exchange on page 3:

“It’s a simple matter of reconnecting a wire that was disconnected or cut on U.S.A.-bound cars; however, gaining access to the wire in order to reconnect it is not very easy.
The disconnected wire will be found doubled over and taped up, immediately behind the fuse block. In addition to regular and Phillips screwdrivers, you will need a hemostat or equivalent pliers and a solderless-terminal compression tool with proper connector.
For safety’s sake, disconnect the battery before starting the job. Remove the fuse block cover and unscrew the two Phillips head screws that secure the fuse block to the firewall. Locate the taped up wire, remove the tape, and fasten a connector to the end if it does not have one. This wire must then be added to the #1 fuse terminal, on the end with the most wires. Use the hemostat or equivalent to pull the fuse block back into position and refasten it with the Phillips screws. – F.M.”

 

[DerFuror]

Did you have to open up the harness to find the wires? What color are the lead wires ?

My shop wiring diagram stated the wire color. I vaguely remember first investigating the wiring coming off the back of the headlight switch to verify its existence (which it did).

I then did open the harness covering to locate the wire ends. Before doing any exploratory slicing, check areas along the harness where the covering may be worn (e.g. behind attachment brackets along inner fender wall).

Having done the job so long ago, I no longer remember wire color & all of my info goodies + car are tucked away for Winter.

 

[helleifenbein]

Thankyou
DerFuror, Climbernyc, others. I have found that my car does have the wiring behind the light housing. There is a junction plug that has all the wires plugged into it there is a grey/green wire that is not wired to anything. I gave it a test and that is the lead that runs to the light switch and when you turn the lights on and pull it fires up the fog light that I have set up as a test. That was just the drivers side (U.S. version) Not sure of the wire color on the passenger side but I know how to find it now. I still have to fabricate some wiring and a relay, but I am pleased that I dont have to go digging at the light switch, as access is limited on the 250s. I will post some pictures when done.

 

[helleifenbein]

From some help from this forum I have gathered some info on installing some driving lights/fog lights on my 1967 w108 250s. Over the next couple of weeks I plan on documenting my little task so that others will have info on this task. Tonight I began by getting to the lead that runs to the switch. which is located behind the head light housing. Not all models are the same as years progress so if yours is different-research your metal mates.

First removed the chrome trim that surrounds the headlight housing, screw is on the bottom, then remove the four screws that attach the housing to the fender.

Behind the housing is a junction that connects the housing to the harness, our wire is within this unit, two screws remove it from the housing, then you can put the housing in a safe place. be careful the junction has a circuit board that is fragile. I know because I broke it on the other side when hunting around. With the junction removed from the housing it is free for inspection.

If you flip it to the circuit board side you will see 5 connections with wires soldered to them, except for one that is missing a wire.. Thats the bugger we want.

If you flip it over and carefully remove a plastic cover you can see all 5 wires, note that the wire that connects to the lead that has no wire on the other side is the wire we want to use(on my car it is Grey/Green,) it is a lead that goes through the wiring harness up into the dash at the light switch and is factory wired for our accessory lights

We are left with a couple options,

I thought about soldering to the lead to complete the circuit, but i chose to remove the wire from the junction completely. I will then use the connection to run priming wire back out of the fender along the harness to a 12 volt 40 amp relay and further along to complete the circuit.

I have the relay on order and is on route, so for now I am left with cleaning up the terminal junction wires and head light buckets as they were in dire need of a good detail.

I will keep ya posted as I progress
Cheers
Dave