bobsails

Old member from my W107 days I had 2 a 1984 and a 1985. They were a lot simpler than the 2005 CLK 320 I just purchased..
It is in great condition with just 50k on the clock. But when buying used there is always something to fix.
I have just about everything squared away till I got to this lighting problem, and I did do a lot of research before starting this post.

First let me say this is NOT an LED problem these are stock bulbs.
Not long after purchase I received the "Left License plate light was out" message. Investigating I found that the bulb was not burned out but pulsed on and off about 10 seconds between pulses.

So I purchased and changed the left bulb, that did nothing the new bulb still pulsed.
I tried the right bulb in the left socket, that still pulsed.

I went to the dealer and bought 2 new bulbs and changed them both, the left bulb still pulsed and the same error message.
I took off the trunk cover and wiggled the harness and everything under there looked pristine, it still pulsed.

So now I am here looking for some help or a direction to head down. I did also shut off the convenience option on the dash but that didn't help either.
Anyone with some new ideas would be most appreciated and thank you.
Bob

HETPE3B

Rear SAM module playing games?

Rudeney

Thoroughly clean the contacts. Also, you nay need to remove the lens/socket assembly and check the wiring. It can get burned and brittle over time from heat and environmental exposure.

bobsails

Thank you for the replies.
First Rudeney I did clean the contacts with contact cleaner and checked the wiring in the trunk to the SAM.It looked Ok.
.I bought a used Rear SAM and installed It. The left license plate light is still flashing and then goes out.
Anyone have any ideas?
They will be much appreciated.

bobsails

I also removed the left socket and checked it with the feed to the right socket it worked perfectly.
Now I guess I will bypass the wiring from the SAM to the socket and try that.

bobsails

Update, I cut the wiring to the SAM and installed a direct connect piece no change to the flashing. I also checked the ground and that was not the problem.
Here is the sequence of the flashes.
Lights on it flashes 11 times with 5 sec intervals of being off stays on about a second.
After the 11th flash it does not flash anymore. It is completely out.

Has anyone any ideas, I am out of them now?
Thanks,
Bob

bobsails

Final Post problem solved.
Thanks to this post.
..https://www.benzworld.org/forums/c20...then-dies.html
I checked the tail light assemblies and found the Accura dealer were I had purchased the car, must of installed
the wrong bulb in the taillight assembly.. The SAM looking at overall impedance as a mismatch must of tried the license plate light
and shut it down. Interestingly the incorrect taillight bulb was on the same left side.
Thanks for the help.

Rudeney

That basically means the SAM has detected it as being a blown bulb. It flashes it a few times just to "be sure" and then shuts it off. Can you swap the wire at the SAM for the left and right lights to see if it follows the side?

HETPE3B

Assuming there is the same system as BMW is using - by flashing the light SAM is measuring the current going through the circuit. If the current is lower than specified SAM is thinking that the bulb is blown. Now, since you did replace the SAM and the problem is still exactly the same (correct me if I'm right ) there is not enough current cruisin' through the circuit. I assume, that SAM is controlling the positive wire (again correct me if I'm wrong) j- measure the resistance between the output by the SAM module and positive wire connector that plugs in to the bulb (remove the bulb first) and also measure the resistance between the ground wire connector that plugs in to the bulb and between the any ground point. The resistance should be close to 0 ohm in both measurements. If resistance is significantly higher - that's your culprit.