Problem : Front parking and/or rear tail light out on 1 side of the car only, causing OBC warnings. Sometimes intermittent and erratic, so you get the impression these are false warnings. This only happens when lights are on. Changing the bulbs doesn't seem to solve this problem.
Strange enough, in most of the cases the left side (driver side) goes out.
Models: every model from '86 to '92.
Additional information: the whole E32 community can confirm this problem is due to the infamous mustard relay. This relay is identified by it's color, some dark yellow mustard color (what a surprise!). Virtually every E32 will suffer from this problem sooner or later, a very common fault.
It's located in the fusebox under the hood. It's one relay module with 2 integrated relays for controlling the left and right side bulbs. After '92 the design changed and the relay was integrated into the LKM module.
Of course you can buy yourself a new relay but they are expensive, about 60 bucks. A used one isn't recommended, I recently bought a 750il for parts and the first thing I did was simply swap the mustard relay. Unfortunately, the other relay suffered from the same problem so now I have 2 bad relays. But it's easy and cheap to fix by yourself because the problem is caused by weak solder joints inside the relay. All you need is a soldering iron and some soldering skills.
So let's
get soldering:
First identify the
correct relay inside the fusebox. You can simple remove it by
yanking it upwards:
This is the correct relay, with
SKM stamped into it. It's an original HELLA component:
The relay has 3 tabs underneath:
First pry out the upper tab, a
small lid will open:
Then pry out the 2 tabs at the
side. I used 2 small flat screwdrivers for this:
Now pull the relay apart:
Carefully examine the surface:
Soon I discovered some bad
points. Sometimes it needs a experienced eye to see this:
If you are in doubt, resolder
the whole printed circuit board like I did:
Keep in mind that when you refit the PCB into the case, there is a slot in the case. It fits in one position only.
Total
amount of costs :
None!
We want more of these easy-to-fix and cheap repairs.
Skills needed/difficulty level : it helps to have some soldering skills. You don't want to solder the solder pads together. That will lead to unpredictable behaviour like blown fuses, wiring harness meltdowns and so on.
Story by Sean750.