W124 E320 lights not working.

[Das_Boost]

To quote the grinch “there's a light on this tree that won't light on one side.”
And that’s what’s going on with my 95 E320 wagon / estate. The passenger (right) side tail light & front corner marker light will not illuminate.

The specifics:
The flasher on front (same bulb as corner light) works. Brake light, reverse light, and turn signal on rear all work.

What I’ve done:
So I checked fuses and played around swapping them out for fresh ones & swapped fuse 3 & 8 for left side lights. And the symptoms remained the same.

I have cleaned all the fuse holders when I replaced all the fuses 6 months ago. I pulled the N7 relay today to check for corrosion and found none. But I cleaned all the terminals to be safe.

The warning buzzer, license plate lights, etc all work (all in same fuse circuit as right parking / tail light on fuse 3)
The bulb out indicator works, I confirmed this as I had a brake light out. This is how I noticed the lights weren’t working, but I’m not sure how long this has been going on as the car was parked for 9 months. I replaced that bulb, and the indicator warning light turned off.

Any help would be greatly appreciated in solving this...
All exterior bulbs are new (or brand new bulbs have been used to test). All fuses are 6 months old & tested. I’m at a loss on this one.

Thanks in advance.

[Usaguy]

Originally Posted by Das_Boost

...The passenger (right) side tail light & front corner marker light will not illuminate.

The specifics:
The flasher on front (same bulb as corner light) works. Brake light, reverse light, and turn signal on rear all work.

Ok good info so let's diagnose it.

Wiring diagram for lights on your car:
http://www.w124-zone.com/downloads/MB%20CD/W124/w124CD1/Program/ETM/24821300.pdf


1. tail light

How the power goes:

N7 -> E4x1 connector -> tail lamp -> E4x1 -> W7 ground

I think we can eliminate a bad ground since all other lights work.

Find connector E4x1 (should be behind the passenger side trunk panel)

Disconnect the connector and find terminal number 6

With a multimeter put one probe to ground and the other probe in terminal 6 check if you're getting voltage.

This way we will narrow down to where the problem is.


2. Front marker light

Because your flasher works then we can say that the ground point W10 is good.

Disconnect the right side turn signal/marker light connector.

With a multimeter put one probe to ground and the other probe in terminal 4 check if you're getting voltage.

Terminal 4 goes straight from the N7 relay.


do these 2 tests and then we can diagnose it further.

[Das_Boost]

Originally Posted by christuna

Ok good info so let's diagnose it.

Wiring diagram for lights on your car:
http://www.w124-zone.com/downloads/MB%20CD/W124/w124CD1/Program/ETM/24821300.pdf


1. tail light

How the power goes:

N7 -> E4x1 connector -> tail lamp -> E4x1 -> W7 ground

I think we can eliminate a bad ground since all other lights work.

Find connector E4x1 (should be behind the passenger side trunk panel)

Disconnect the connector and find terminal number 6

With a multimeter put one probe to ground and the other probe in terminal 6 check if you're getting voltage.

This way we will narrow down to where the problem is.


2. Front marker light

Because your flasher works then we can say that the ground point W10 is good.

Disconnect the right side turn signal/marker light connector.

With a multimeter put one probe to ground and the other probe in terminal 4 check if you're getting voltage.

Terminal 4 goes straight from the N7 relay.


do these 2 tests and then we can diagnose it further.

Thank you very much for all this information. I started to test everything last night, and after reading some other threads somewhere on the web where people experienced similar issues, a few people mentioned a broken solder connection inside the N7 relay itself. So my curious mind decided to open it up and check. Sure enough one of the solder connections was cracked. I reflowed the solder, and reinstalled, and all the lights worked. I’m positive I got lucky finding that, and I really appreciate the link to the wiring diagram. I’m saving that for future reference.

However I have noticed that if the relay is jiggled or moved, the corner light “connection” comes and goes, and the front right fog light will occasionally do the same. The rear tail light works as it should 100%. So at least the most important light is functioning.

I’m wondering if I should just replace the N7 relay to be safe.

[Usaguy]

Originally Posted by Das_Boost

...I reflowed the solder, and reinstalled, and all the lights worked...

Good.

I had a feeling that it could be the N7 because only one side parking/tail lights failed and looking at the diagram the power coming into the N7 is not split by sides and it is the N7 that splits the power into individual places.

Also here's a link to a wiring diagram index for 1993 and newer W124:

http://www.w124-zone.com/downloads/MB%20CD/W124/w124CD1/Program/ETM/wiring_index.pdf

also check out the http://www.w124-zone.com/downloads/MB%20CD/W124/Main.html website. It has a factory shop manual for your engine, chassis, climate control etc etc...