BMW M5 Forum and M6 Forums banner

1 - 2 of 2 Posts

·
Registered
Joined
·
21 Posts
Discussion Starter #1
Gents,

Recently started getting a "check low beams" error and I do have one headlight out (other lights and the halos on that side are working). I replaced the bulb with a new Osram unit and still no light. I've searched the forums and elsewhere but still have a couple of questions:

- Reading the owner's manual, the 5 Series Bentley manual (which does not specifically cover the M5), and a variety of on-line sources, I cannot find mention of a fuse for these headlights to determine if there is one per side or one for both - does anyone know in which fuse box a fuse may exist or if the lights are powered via the 80A LCM link? If the LCM, could/would one be out and not the other?
- Is the next step to replace the ballast? There are no burn marks or other external indications that the ballast has failed (other than the light being out) but that appears to be a logical next step.
- Any other suggestions for what should have been a simple fix?

Thanks

Steve
 

·
Registered
Joined
·
242 Posts
So for E39 electrical troubleshooting, newtis.info is a powerful source; it's got the wiring diagrams as well as some quite helpful descriptions/pictures to help you find and diagnose stuff. One caveat though is it's sometimes tough to get the EXACT right diagram for your EXACT set of options. BMW isn't know for making its options list very simple or straight forward after all. At any rate, here's my best guess for your lighting diagrams:
+12V supply: Supply
You can see that there's 4 fuses for the LCM (16, 41, 112, and 113).
Lights: Front lightsWith xenon light
There's just one wire for each side that goes from the LCM to each headlight (yellow/green for the left, yellow/blue for the right), and then the brown wires that go to ground.

So you're probably right that it's the ballast resistor, but it's pretty easy to rule out the simpler solutions with a quick multimeter check before you spend that money. Unplug the connector, turn the lights on, and check for +12V on the yellow/whatever wire. I expect it'll be there, but if not then check the 4 fuses and the correct pin (11 or 3) on the LCM itself. Also worth checking continuity to ground on the brown wire, to make sure you don't have a broken/bad ground. When both of those things turn out OK, then order your new ballast. Good luck!
 
1 - 2 of 2 Posts
Top