Where the mustard relay is, opening the mustard relay and resoldering is described on Johan's page
http://bmwe32.masscom.net/sean750/mu...stardRelay.htm
and E32fixes.com
http://www.e32fixes.com/results.asp?...ow_fix&fixid=1
So I will not go into detail for this.
Repaired 2 mustard relays yesterday.
While one relay was o.k. after resoldering, the other one still had a fault message tailt light, although the tail light was o.k. So tested the relays on the soldering contacts with a DMM (Ohm) and found faults.
De-soldered the relays and used a small strip of very fine emery paper to clean the contacts of the relays. This is very often the cause of the fault. But still the fault message came up in the check control after testing it on the car.
Finally it turned out that the cause was the pressure of the contact on one of the 2 relays inside the mustard relay, it was not enough or may be damaged to make poor contact.
Bent the lead of the contact a little bit to give more pressure when relay was activated.
Checked it again on the car and it was o.k.
As far as I know only E32 with LKM-L have a mustard relay, while E32 with LKM-B have in the same position a socalled daylight relay. That is much less complicated as it just has the blades and the connections, no electronic inside.
Here you see a mustard relay and the daylight relay
http://s71.photobucket.com/albums/i1...gAnch=imgAnch1
You can see the connections and the missing ground pin on the 'dummy mustard relay"
So not always soldering will cure an mustard relay.