BMW Check Brake Light & Check Rear Lights Circuit Faults – All Models
This answer is applicable for many BMWs in addition to the one listed below.
car year: 2004
car model: X5 4.4i
Hi, been getting for quite a while an intermittent dash message. “Check Brake Lights” & “Check Rear Lights” Have also been told at times we have a brake light out. I replaced all the bulbs and 2 sockets with BMW parts and problem still exist. One thing I notice is when you install the bulb and socket into the light assm. you have to back the socket out slightly to get the lights to work. My guess is the light housings are defective in some way. Do you know what might be the cause and a simple solution.
In this case, you may have poor contact between the bulb socket contacts and the contacts in the tail light housing (as potentially indicated by your notes on the socket installation) or you may have poor contact between the vehicle harness plug and the harness plug socket on the tail light.
Poor contact between the vehicle harness plug and the socket on the tail light is actually very common on many of the later model BMWs. We would suggest that you inspect the individual bulb socket contact points and look for corrosion or pitting. Clean or replace as necessary. Secondly, make sure that the harness plug contact pins are making a secure connection to the pins in the receiver socket.
Finally, apply the DeoxIT contact cleaner and enhancer to all of the bulb socket and harness plug contacts.