Electrical Issues

[Rfabz]

Hi,

Having some pretty strange issues with my car’s electricals - 135i 2008.

The interior lights (footwell, steering wheel lights and cigarette lighter) are always flickering. I’ve noticed I can stop the flickering by depressing the brake pedal.

My reverse lights also come on when I brake along with rear parking sensors, but not when I am actually in reverse.

Possibly a bad ground, but I’m not sure where/how to check.

Any suggestions?

[GoRomeo]

Why I keep seeing lots of issues with 2008’s ?! I just bought one. 🥹😀 Anyway yeah that would be the first step if I were you. Then battery. Do a load test see how its holding the charge? Auto parts store can do this for free. Also have them test the alternator while you at it. Good luck 👍

[Rfabz]

Originally Posted by GoRomeo

Why I keep seeing lots of issues with 2008’s ?! I just bought one. 🥹😀 Anyway yeah that would be the first step if I were you. Then battery. Do a load test see how its holding the charge? Auto parts store can do this for free. Also have them test the alternator while you at it. Good luck 👍

Haha yeah I got this one about a month ago lol, hasn’t been the easiest ride so far!

Already ruled out the battery as I got a new one thinking it would solve some issues. Not sure about the ground issue how I would actually check or where the ‘grounds’ are.

[GoRomeo]

Ok, I hear you. Im going through some too. But Its worth it. To drive these cars are so much fun. Try to look for ground straps inside the engine bay. The e90s have 1 underneath the car. Do some Google search.

[NorthernDancer]

85% of all weird electrical issues are caused by loose and/or dirty connections. The very first place to look is a mesh grounding cable very low on the drivers side. I think it goes between the starter and body ground. Most BMW indy garages automatically change the cable with their home made cables when they come into the shop.
Second place to check is ALL battery cables from battery and up and inside the engine compartment.
Owning a BMW can cause huge amount of heartache if you don't use a BMW indy garage. Also join BMWCCA which also gives you membership to your local chapter and people who know BMWs well and all the best garages.

[Rfabz]

Still haven’t managed to crack this.

But I think I’ve made some more deductions.

A ground/shirt issue I feel could mean that the reverse lights/sensors come on with the brake, but they would likely be flashing/intermittent. And I think certainly that wouldn’t stop them coming on when actually in reverse.

It’s also both reverse lights, meaning that the issue must be somewhere that is before the two rear light looms. Could it be possible that someone has wired the reverse lights directly to the brake? The same way in which it would be wired to the reverse gear but it’s been wired to the brake instead?

I have no idea where I’d check that though, I’m not sure where those two components marry up.

Google diagrams aren’t proving the most helpful either, I just keep getting results for people changing their automatic to manual!

[PRTSB1M]

Have you checked the tail lights are wired correctly and using the correct bulbs? Lots of folks do cheap mods/hacks to the lights on these cars.

[Rfabz]

Originally Posted by PRTSB1M

Have you checked the tail lights are wired correctly and using the correct bulbs? Lots of folks do cheap mods/hacks to the lights on these cars.

They are aftermarket lights but should be plug and play so should be no reason for any wires to be wrong.

I’m not sure if wrong bulbs would cause the issues I have. Maybe if it was just X bulb not working but I don’t think wrong bulb would cause my reverse lights to only come on when the brake is pressed surely?

Could this be an FRM module issue?