Experimenting with LED headlights for the e32 - funny LKM behaviour

[Axel4]

Hi everyone,

Does anyone have experience with replacing the H1 halogens with these modern LEDs that now match HIDs in brightness? I bought some to test things out. Fitting is a bit fiddly but can be made to work, but the LKM and Fault Detection units go haywire. One can fix error detection with resistors, but the LKM has a real problem: it tends to switch off one rear light and one brakelight when the LEDs are installed, when I put the halogens back in it takes a few hours and everything is back to normal. The logic in the LKM is quite obscure and I cannot find any description on it. But why would replacing 55W halogens with 35W LEDs (with ballasts) make the LKM go funny in the head?

Any advice gratefully received.

[CamE32]

So as a disclaimer, my cluster's OBC display isn't working.

But I bought these LED headlight bulbs off Amazon and they've been working great: https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
They were truly plug-and-play, and I've had no issues with the LKM doing anything funky. I imagine I'd hear a 'ding' if my OBC sensed any bulbs burnt out due to the LEDs... But given my sad cluster situation, I can't confirm 100%.

But I'm pretty sure as long as you get true 55w LED's (so the electrical draw is the same as halogens), then you shouldn't have any issues.

[shogun]

"but the LKM has a real problem: it tends to switch off one rear light and one brakelight when the LEDs are installed, when I put the halogens back in it takes a few hours and everything is back to normal"

>>>The LKM has in your EURO version 4 relays only, low beam, high beam, front foglights, rear foglights

but no relay for brake light and taillight. resolder for a test the mustard relay http://bmwe32.masscom.net/maxf_websi...lay_repair.htm

[youngbimmer]

So as a disclaimer, my cluster's OBC display isn't working.

But I bought these LED headlight bulbs off Amazon and they've been working great: https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
They were truly plug-and-play, and I've had no issues with the LKM doing anything funky. I imagine I'd hear a 'ding' if my OBC sensed any bulbs burnt out due to the LEDs... But given my sad cluster situation, I can't confirm 100%.

But I'm pretty sure as long as you get true 55w LED's (so the electrical draw is the same as halogens), then you shouldn't have any issues.

What is the beam pattern like with those?

[Axel4]

What is the beam pattern like with those?

Thanks for the advice Shogun. I'll check it out.

I tried the LEDs and compared the light pattern against the garage door. Better than the halogens, the "cut off" was sharper. But I haven't yet checked it out on the street, due to the other lighting problems. It's my next step.

[6erWEBB]

Oh you guys need to post pics, I was thinking of this!! And which bulbs you used. I've been researching swapping to the led bulbs on our powerstroke tow rigs recently..

[shogun]

from the E31 section https://www.bimmerforums.com/forum/s...ght-conversion

[white 750il]

I have a 89 BMW 750il trying to buy aftermarket headlights for it it says it will fit a 735 ilbut not 750 il what are the difference between them?

[shogun]

They basically fit in the whole E32 series and E34 series. Turnlights are different on E32 and E34.
It is different for some countries like in the EU, where cars need headlight aim systems. The 735i needs such a system with an electric motor behind the headlights, the 750iL not because it has self levelling system on the rear.
So a 735i needs headlights (at least in Europe) which can be controlled by head light aim control motors. The 750iL not.
Bulbs and connectors/plugs are different between US and EURO versions

[Axel4]

"but the LKM has a real problem: it tends to switch off one rear light and one brakelight when the LEDs are installed, when I put the halogens back in it takes a few hours and everything is back to normal"

>>>The LKM has in your EURO version 4 relays only, low beam, high beam, front foglights, rear foglights

but no relay for brake light and taillight. resolder for a test the mustard relay http://bmwe32.masscom.net/maxf_websi...lay_repair.htm

Shogun, you were of course quite right. Independent and intermittend problems confused me, but now all is well. I resoldered the Mustard Relay today, a 20 min. job using the instructions you sent. When putting on my readying glasses (or someone else's) it is quite obvious where the problems are, just like in the pictures. Many thanks.

Now back to the LED headlights. I am ordering the 55W LEDs so that the error detection measures the same current as with the halogens. I will update when ready.