2004 325i Tail liight issue

[dydigital]

I have one parking light bulb on the driver side tail light that shows error and doesn't come on. i can't figure out the issue. I changed the bulb already. I checked the wiring and everything seems fine. When i use a test light on the wire for that bulb on the clip the test light is very dim like its not getting enough power to light up the bulb. The wire for the bulbs that light up the test light comes on normal. I did the whole new ground wire thing for both tail lights a very long time ago so I don't think it can be that. I also checked the wire loom for the trunk lid but didn't find any broken or crimped wires. But i also taped that up real good and put it back together

I had this car over ten years but the problem started back in March when i was on the highway and I seen the dash error indicator light come on. It went off and on for a month and now it just always shows error and doesn't light that one bulb. Turn signals and every other light on the car work without issue. Not sure it it's related but my one rear internal cabin light in the back seems to flicker which never did before the issue but could be cause i switched all those interior lights and light plate lights to led lights a bunch of years back.

From what i read the LCM only controls the exterior lights so not sure it the interior light is related to the tail light issue. I dont really care about the interior light but there are 2 light bulbs that come on in each taillight with the parking lights. Only the 1 inner bulb is out in the left tail light.

I do have the Pa soft and cable so was thinking to check the LCM for errors? Not sure what it will tell me in detail tho. Also If i plug the left tail light bulb housing on the right side then both bulbs seem to come on fine. So i don't think its the light bulb housing. But what was weird, if i plug the known good right tail light housing into the left side i only get the trunk light no bulbs all come on so that threw me off completely. I don't see any other E46's with the issue so i am at a loss. I don' want to buy a new lcm if its not the fix. Sorry i am not good with electrical problems. Also was thinking about getting a tester to test the wire from the lcm all the way back to the trunk but llike i said i never mess with any wiring in the car. . I added Angel eyes but i disconnected completely to see if that was the issue but no change and i still have the rear bulb out. Other then that i have a aftermarket head unit but I never had issues with that all all.

Please any help would be appreciated. sorry for the post

[Muzz258]

Hi

Its a fairly easy circuit to fault find. See below. Voltage comes from a separate terminal on the LCM straight to the tail light bulb. Check the voltage at the bulb with a volt meter. If its less than 12 V, pull the LCM and check the voltage at pin 30 at connector X12.
https://www.newtis.info/tisv2/a/en/e...r-left/pR6SUM9

[dydigital]

Your the man thanks for the guidance. I will check it out

[randy72877]

There is a common issue with the ground terminal at the harness connection with the bulb holder. You did check that right? They burn causing poor ground. It's the brown wire.

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