While troubleshooting some electrical problems I incidentally learned a whole mess about the Bulb Monitoring Unit (BMU). After chasing multimeter readings around the whole wiring harness I concluded that my BMU was dead/dying, so I decided to bypass it in hopes of catching my electrical gremlin. I found a bypassing the BMU guide elsewhere on the internet, but nothing about reconnection if you forget where everything goes so I'll just put it all down here in once place.
To bypass the Bulb Monitoring Unit:1.) Remove spade connectors Grey/Yellow, Grey/Red and Grey/Green from the
BMU main connector and connect all three together. The smaller female spades of Grey/Red and Grey/Green will slip onto the loops of the larger Grey/Yellow female spade.
2.) Remove spade connectors Grey/Black and Grey/White from the
BMU main connector and connect both together. Just offset one and they will be able to slip together.
3.) Cover both of these separate connections with electrical tape (or something else insulating, heat shrink tubing if you are making this bypass a more permanent mod) so they don't short on each other and leave the rest of the unused connectors in the
BMU main connector.
4.) Remove BMU to keep it out of the way inside the relay box and you are done.
To reconnect the Bulb Monitoring Unit:After I discovered that the BMU wasn't my particular problem, I decided to reinstall mine (personal preference). Problem was... I didn't remember where all the wires went inside the
BMU main connector. So I figured it out:
Each line in the BMU main connector diagram represents one slot in the BMU main connector, long lines for the larger slots, short lines for the smaller ones. Labels to the left of each slot are labels on the BMU itself and labels to the right are wire connections and their purposes for clarity. Diagram is if viewed from above after removing the BMU itself.