one headlight only half bright

[jimbom30cab]

e30 325i aug 87

The driver's headlight is only half bright, it's connected to the yellow and blue wire.

I've changed the bulb with a known good one and tested there is 12v at the plug.

Also changed the relay with a known good one

I suppose it could be:

1. dodgy earth ? not sure where they earth to at the moment
2. wiring fault ?
3. Plug connection weak?
4. Light switch ?

Anyone seen this before??

cheers

[broadie]

It won't be the switch. Do the fuses run left and right?

Id go for bad connection/earth.

[macas]

Check the earth connection right next to the lamp,its a push on round connector,give it a wiggle and see if the lamp gets brighter....

[jimbom30cab]

thanks guys, i sorted it in the end

there was a fault with the live cable between the fuse box and the lamp

i ended up cutting the cable under the fuse carrier and bridging to the same wire just behind the left headlight (where i cut it to make a junction)

all worked fine then

just need to now solder in new wire under the fuse box and thread it to the connection i made by the left hand light cluster

PITA job as it wasn't the normal earth or loose connection problems.

no obvious issues with the wire and i didn't test the duff section for resistance as it was getting late, i've sorted it anyway.

ta

[jmc330i]

If I've read that right, you have wired the drivers headlight to run from the passenger headlight??

[jimbom30cab]

http://shark.armchair.mb.ca/~dave/BMW/e30/e30_87.pdf

I just replaced the YL/BU wire here on page 96

[jmc330i]

Sorry, was confused by you saying drivers headlight in your first post and left hand light in another - it sounded like you had joined both headlights to one fuse!


Just out of curiosity, when you have the sidelights on with the ignition, is it only the sidelights that are on, or do the dip beam bulbs light (at reduced brightness) as well? - there was a dim dip function available to do this. The should be a resistor pack on the inner wing, behind the headlight if its fitted.

[Brianmoooore]

Just out of curiosity, when you have the sidelights on with the ignition, is it only the sidelights that are on, or do the dip beam bulbs light (at reduced brightness) as well? - there was a dim dip function available to do this. The should be a resistor pack on the inner wing, behind the headlight if its fitted.

Very good point! Yellow/blue is the wire to the RH dip beam, and if you have dim dip, the wire from the fusebox to the light takes a diversion via an orange relay at the left rear of the glovebox.
If this relay has failed or is loose in its socket, then you'll get a half bright light.
There are two relays, one for each side, and they are identical to the other orange relays in the fusebox.

[jimbom30cab]

There are two relays, one for each side, and they are identical to the other orange relays in the fusebox

I'll have a look at these relays - do you know what they are for as i can't seem them on the curcuit diargram.

I did trace the wire and the yellow/blue goes directly from the bulb to the fuse. There is quite a bit of loom tape on still so i may have missed a splice hidden though.

Brian, you mention the relays are orange but all my relays are Grey apart from the 2 black ones.

[Brianmoooore]

The only circuit diagram I've ever seen that shows these relays is the one I've drawn myself after stripping down an old loom.
The relays, if fitted are behind the LH side of the glovebox, not in the fusebox. There can be up to four fitted there - windows/roof with the doors open, starter inhibitor on autos, and the two in question here.
Are you sure the yellow/blue from the headlamp actually goes to the fuse once it enters the fusebox, and not down through the duct into the cabin in the base of the fusebox?

[jimbom30cab]

Yer pretty sure there is only one yellow blue coming in the fuse box from the loom and it goes straight up to under the fuse carrier.

I've wired up a new wire and it seems to work fine now.

Cheers