W211 OEM iPod Kit Issue - Battery Drain

[Major774]

I finally found out that the OEM iPod kit that one of the previous owners installed is causing a slight key off battery drain, approx. 100 mA.

http://www.mercupgrades.com/IPOD+Retrofit+in+E++CLS+Class-article-62.html

If I pull out the grey relay (see picture in above guide) I can see a drop of approx. 100 mA. When I reinstall the relay I hear a click and the drain is back. Also I note the relay is warm to the touch compared to the other relays.

• I have tried a brand new relay from Mercedes, this made no difference, same symptoms as above
• I have tried disconnecting the iPod black box which is located under the glove box, no drop, continues to drain
• I have tried disconnecting the aftermarket bluetooth module which is connected to the iPod kit, no drop, continues to drain

Does anyone have any other ideas I could try? Or is it a case of live with it, or take the kit out and go back to the aux. port.

 

[richard]

The grey relay (relay C), if I recall correctly should turn off after a while.
try pulling fuse 5 from fusebox which is the power to the contact side of that relay and thus the iPod kit but leave relay in and see if you still have current drain. Ie is it the relay itself causing drain
I’ll try and see what controls relay if I get a chance later. But as I say I’d expect it to turn off.

 

[Major774]

Thanks Richard.

I will give the battery a full charge and try this, I will report back.

 

[Major774]

Ok... Pulled the fuse (5) and the relay did not de-energise.

I remembered a while ago, fuse 64 in the front SAM showed up some thing in my battery drain investigation. So I wondered if the 2 fuse/relay are connected. After pulling and re-installing fuse 64, I then re-checked the relay. The drain did go down and the relay was not energised (I pulled the re-installed the relay, there was no clicking sound).

However, this would all reset after an lock/unlock cycle of the car. Which means I would need to pull and re-install fuse 64 every time. It appears something on the fuse 64 circuit is not de-energising the relay.

 

[BlackC55]

Does fuse 64 power anything else?

 

[Major774]

Yeah, based on this link: Cluster lights - MBWorld.org Forums

I know the iPod kit has to plug into the CAN B Connector (X30/6) as well.

 

[Major774]

Update... Can a mod change this to solved.

I found out that if I disconnect the negative terminate, then hook up a multimeter for an amp. draw test. This would keep actually keep that specific relay energised, unless I pulled and replaced fuse 64 on the front SAM. So this method of searching for a parasitic drain is actually providing a false parasitic drain (relay in my case), and a false resting amp. draw reading (key off).

If you are looking for a parasitic drain, a better method is to perform a voltage drop test across fuses. Without touching the battery, I left the vehicle in its key off resting position. I then checked that specific relay and, lo and behold, that relay was off, pulling and re-installing that relay produced no click sound. So Richard is correct, that iPod kit relay should be turned off.

Conclusion, even a 2004 vehicle is sensitive on how you actually go about and perform a parasitic drain test. I would suggest a voltage drop test over the widely recommended, hook up a multimeter to the negative battery method. You may end up with a false fuse/relay draw that will have you running round in circles.