What purpose does the 'Rear Left/Right Light' Serve?

MintyFresh · 06-10-2021, 05:32 AM

Hi Guys,

I've been trying to solve this for hours and have become rather frustrated

One light on both sides switches off 6 seconds after pressing the brake pedal. It is the one next to the brake light, but the error is different and is called up as a 'Rear Left/Right Light' on the dash.

I have swapped bulb holders, brand new battery, checked the connector and pins, voltmetered every cable.

If I test the relevant pin, it maintains it's voltage. It's not until a bulb is inserted that the pin drops to 0 volts, or more exactly 0.07volts.. It's almost like the bulb draws more amps and trip something up the line.

I am absolutely stumped. I think the next step is to replace the FRM, yet everything else in the car is fine, save for an corning light error (on a pre-LCI car...).

FRMs are hard to get in NZ, any other suggestions before I stump out for one?

Red circled bulb is the brake light, blue is the rear light. Both are activated by the brake pedal. These are in the quarter panel, not the trunk.

Socket · 06-10-2021, 11:20 AM

not 100% clear on what you are trying to solve. what caused you to start looking at your quarter panel bulbs? was it a dash light, a bulb not working?
If one of your bulbs is playing up read the CCID code and it will tell you which one is faulty

https://www.endtuning.com/ccidcodes/

https://www.1addicts.com/forums/show....php?t=1185634

MintyFresh · 06-10-2021, 04:58 PM

Quote:

Originally Posted by Socket

not 100% clear on what you are trying to solve. what caused you to start looking at your quarter panel bulbs? was it a dash light, a bulb not working?
If one of your bulbs is playing up read the CCID code and it will tell you which one is faulty

https://www.endtuning.com/ccidcodes/

https://www.1addicts.com/forums/show....php?t=1185634

Hey Socket,
CC-ID is 123 and 87 for the rear bulbs so 'Right Rear Light Failure' and ' Rear Light Right Failure'.

Interesting how the both say right, when it is the same bulb in the left and right quarter panels.

Both these lights were out when I was doing a light check on the car. I figured it was a broken bulb so I replaced them to no avail. Tried wiggling the bulb incase it was the lose connector, nothing. Measured for voltage, nothing.

After removing the connector and replacing it, the bulb comes on for about 6 seconds, then clicks off. It's almost like it resets something in the FRM briefly?

shannon1 · 06-10-2021, 05:25 PM

Hi MintyFresh,

I'm not sure about our E9X series cars, but I remember the problems and heartache I had with my E46 rear light error always coming on after checking everything.

It ended up being a poor earth connection on the wiring harness plug pin going into the light bulb housing due to oxidation/light corrosion on the surface of the connector pins.

To fix it, all it needed was a light sand with a small piece of sandpaper or a light file with a needle file on either side of the pins to scratch the oxidation layer off exposing nice shiny metal to make a good electrical contact when plugged in.

Have you tried something like that yet?

MintyFresh · 06-10-2021, 05:38 PM

Quote:

Originally Posted by shannon1

Hi MintyFresh,

I'm not sure about our E9X series cars, but I remember the problems and heartache I had with my E46 rear light error always coming on after checking everything.

It ended up being a poor earth connection on the wiring harness plug pin going into the light bulb housing due to oxidation/light corrosion on the surface of the connector pins.

To fix it, all it needed was a light sand with a small piece of sandpaper or a light file with a needle file on either side of the pins to scratch the oxidation layer off exposing nice shiny metal to make a good electrical contact when plugged in.

Have you tried something like that yet?

Hi Shannon,

Thanks for the assist. I've actually gone out and got another set of bulb holders thinking they could be the problem. Same thing occurs with that set.

I've pulled all of the pins from the connector also and tried a few things there too.

I believe it has to be something up the line as the relevant wire has power until you stick something that has a larger draw than the voltmeter, in this case the bulb. The power draw seems to me to be making something trip out up the line.

More and more this sounds like something bad in the FRM. I have a diagram from the Bently Manual. Looks like the circuits go to a 30ohm?? resistor in the FRM. Anyone with an electronics background got any ideas?

MintyFresh · 06-10-2021, 05:53 PM

Further, I think I have ruled out a grounding issue. I removed both tail light pins from the connector and plugged them into the housing. Instead of plugging in the ground wire, I ran a separate wire direct to the battery. Same problem occurred, both turned on then after 6 seconds, one turns off.

If I wait like 10 seconds with the connection ungrounded and do it again, same thing.

Socket · 06-10-2021, 08:20 PM

Quote:

Originally Posted by MintyFresh

Further, I think I have ruled out a grounding issue. I removed both tail light pins from the connector and plugged them into the housing. Instead of plugging in the ground wire, I ran a separate wire direct to the battery. Same problem occurred, both turned on then after 6 seconds, one turns off.

If I wait like 10 seconds with the connection ungrounded and do it again, same thing.

Pretty sure the car does a circuit test on start. Could the 6 sec cut out be part of the normal fault checking process? Does it happen on the left side as well?
Sorry I'm not an expert on the electrical system. Is there someone from the forum who lives close by that could let you do a FRM swap, just to confirm if the FRM is the problem?

rooks335 · 06-11-2021, 03:25 AM

Had all sorts of fun with rear lights not working and turns out to the be boot wiring

MintyFresh · 06-11-2021, 07:27 AM

Quote:

Originally Posted by rooks335

Had all sorts of fun with rear lights not working and turns out to the be boot wiring

Hi Rooks,

Do you reckon there's a chance that a broken wire in the boot is related to my quarter panel lights? Boot lights work fine. Could be worth a shot I guess.

rooks335 · 06-13-2021, 09:31 PM

Definitely worth a check, carefully pry the top and bottom rubber seals and strip back the rubber wire shielding and check all the wires. You'll find a good bundle of wires leading to all rear lighting and also boot release.

Poiseuille · 07-25-2021, 08:01 PM

hi OP, wondering if you were able to solve your rear lamp issue…
if not, i suggest you try actual oem bulbs from BMW. the problem you describe has been going on for a couple decades, especially with E39 and E46 platforms, and happens when owners source replacement bulbs from the local auto parts store. turns out the oem nickel bulbs have less resistance than generic bulbs and the car sees the difference as a fault. try it, maybe you'll get lucky.

06-10-2021, 05:32 AM	#1
MintyFresh New Member 0 Rep 5 Posts Drives: BMW 335i Join Date: Jun 2021 Location: New Zealand iTrader: (0)	What purpose does the 'Rear Left/Right Light' Serve? Hi Guys, I've been trying to solve this for hours and have become rather frustrated One light on both sides switches off 6 seconds after pressing the brake pedal. It is the one next to the brake light, but the error is different and is called up as a 'Rear Left/Right Light' on the dash. I have swapped bulb holders, brand new battery, checked the connector and pins, voltmetered every cable. If I test the relevant pin, it maintains it's voltage. It's not until a bulb is inserted that the pin drops to 0 volts, or more exactly 0.07volts.. It's almost like the bulb draws more amps and trip something up the line. I am absolutely stumped. I think the next step is to replace the FRM, yet everything else in the car is fine, save for an corning light error (on a pre-LCI car...). FRMs are hard to get in NZ, any other suggestions before I stump out for one? Red circled bulb is the brake light, blue is the rear light. Both are activated by the brake pedal. These are in the quarter panel, not the trunk. Attached Images
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06-10-2021, 11:20 AM	#2
Socket Lieutenant General 4682 Rep 11,956 Posts Drives: 335i Join Date: Nov 2014 Location: Australia iTrader: (4) Garage List 2008 BMW E92 [0.00]	not 100% clear on what you are trying to solve. what caused you to start looking at your quarter panel bulbs? was it a dash light, a bulb not working? If one of your bulbs is playing up read the CCID code and it will tell you which one is faulty https://www.endtuning.com/ccidcodes/ https://www.1addicts.com/forums/show....php?t=1185634 Last edited by Socket; 06-10-2021 at 11:26 AM..
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06-10-2021, 05:25 PM	#4
shannon1 Private First Class 677 Rep 187 Posts Drives: 2007 E91 323i M-Sport Join Date: Jun 2019 Location: Brisbane, Australia iTrader: (0) Garage List 2007 BMW E91 323i [0.00] 1970 Volvo P1800 E [0.00]	Hi MintyFresh, I'm not sure about our E9X series cars, but I remember the problems and heartache I had with my E46 rear light error always coming on after checking everything. It ended up being a poor earth connection on the wiring harness plug pin going into the light bulb housing due to oxidation/light corrosion on the surface of the connector pins. To fix it, all it needed was a light sand with a small piece of sandpaper or a light file with a needle file on either side of the pins to scratch the oxidation layer off exposing nice shiny metal to make a good electrical contact when plugged in. Have you tried something like that yet?
	Appreciate 0 Quote

06-10-2021, 05:53 PM	#6
MintyFresh New Member 0 Rep 5 Posts Drives: BMW 335i Join Date: Jun 2021 Location: New Zealand iTrader: (0)	Further, I think I have ruled out a grounding issue. I removed both tail light pins from the connector and plugged them into the housing. Instead of plugging in the ground wire, I ran a separate wire direct to the battery. Same problem occurred, both turned on then after 6 seconds, one turns off. If I wait like 10 seconds with the connection ungrounded and do it again, same thing.
	Appreciate 0 Quote

06-11-2021, 03:25 AM	#8
rooks335 Second Lieutenant 44 Rep 249 Posts Drives: 2008 E90 335i Join Date: Jul 2015 Location: Perth WA iTrader: (0)	Had all sorts of fun with rear lights not working and turns out to the be boot wiring
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06-13-2021, 09:31 PM	#10
rooks335 Second Lieutenant 44 Rep 249 Posts Drives: 2008 E90 335i Join Date: Jul 2015 Location: Perth WA iTrader: (0)	Definitely worth a check, carefully pry the top and bottom rubber seals and strip back the rubber wire shielding and check all the wires. You'll find a good bundle of wires leading to all rear lighting and also boot release.
	Appreciate 0 Quote

07-25-2021, 08:01 PM	#11
Poiseuille Brigadier General 5427 Rep 3,744 Posts Drives: 2016 M4 DCT Tanzanite/Amaro Join Date: Oct 2016 Location: Princeton iTrader: (0) Garage List [0.00] [10.00]	hi OP, wondering if you were able to solve your rear lamp issue… if not, i suggest you try actual oem bulbs from BMW. the problem you describe has been going on for a couple decades, especially with E39 and E46 platforms, and happens when owners source replacement bulbs from the local auto parts store. turns out the oem nickel bulbs have less resistance than generic bulbs and the car sees the difference as a fault. try it, maybe you'll get lucky.
	Appreciate 0 Quote