lllsmoothoplll

Ok so my can was having battery issues for a couple weeks, so i went to kragen and told them i need a new battery. they looked in the computer and gave me the appropriate one that came up under my model. Dont remember the brand but it was 900cca. if i remember correctly my old one was 680cca.

so a couple days later, today, after i got home i turned off the car and i just kept hearing a continual noise like a vacuum or fan. popped open the hood and whatever this part is that i attached the picture of just kept working. tried reseting and restarting everything but no good. i dont know what it is or what happened? at the end i unplugged the battery so it wouldnt die.

has anyone seen this happen? do you think its the battery?

lllsmoothoplll

TruTaing

I cant remember for the life of me what its called, but I believe it helps warm up the cats when you first start the car. Have you re-installed the battery? Are you getting any malfunction lights or any other issues with the car?

Edit: Secondary air injection pump or something along those lines. I believe if there is a failure with the pumps operation, it should throw a code. If you run the motor for a bit, does it eventually turn off?

Glyn M Ruck

Secondary air injection or excess air pump. It is supposed to run at cold start & help with Cat heating & improve cold start emissions. It should shut down once the engine is warm. It will sometimes run for a short while on shut down & then auto switch off as can the radiator/HVAC fan.

lllsmoothoplll

there were no errors or anything. so this morning i plugged the battery back in and it worked normal, nothing off yet. i just did a ebay search for that part but i cant find it. do you guys know where i can look for one?

Rudeney

I doubt the air pump is bad - it's controlled by the ECU through the front SAM (via relay "O"). The SAMs can be very sensitive to voltage fluctuations. The bad battery might have killed the front SAM. BTW, "SAM" = "Signal Acquisition Module" which is an electronic component that controls various fused devices through CAN bus commands. The W209 has two - the front SAM (fuse block un der the hood) and rear SAM (fuse block in the trunk).

Glyn M Ruck

+1^

betrezra

I'm not a super tech like the guys above......... But from my empirical field data I do find the mb ecu do have glitches at random that can lead to odd behavior..... Which for is solved by simple power down restart for normal op after the anamolous incident.

I've had about 5 of these incidents over the past 5 yrs with 3 diff models.

If no codes on das star..... Then I chalk it up to the equiv of software glitch.

Am I off base?

Glyn M Ruck

These units do suffer brain farts from time to time requiring a microprocessor reboot by shutting down & restarting.

lllsmoothoplll

thanks for all the replys guys. after leaving the battery unplugged for a day the car went on two days without any problems loll.... third day it did the same thing. this time i just unplugged that pump from its power connector. ive been driving it without it on, do you guys think this will damage something else. How should i go about diagnosing this. how do i check the sam?

Rudeney

Check relay "O" on the front SAM. It could be sticking:

http://benzbits.com/W203/FrontRelays.pdf

TruTaing

There are some companies that have build block off plates for this pump for performance reasons and disabling it entirely shouldn't hurt anything except for the environment

lllsmoothoplll

sweet thanks, ill check the relay then. check engine light went off today since ive been driving with it off. i would have just left it as is if it didnt lolll.