silver_benz

I am drawing at least a full amp with everything off. Disconnected both front seats (front and back connectors) and still drawing. Starting pulling fuses and it seems like the ones next to the door all have a partial effect on the amount drawn. I have no fuse schematic anywhere. Manual says it should be in the one by the door but it is not. Trunk fuses have no effect whatsover. If all fuses by the door are pulled amps drop to .5 amps or 500 milliamps. Still way too much. I read that Tele Aid is another common problem.

Three questions:

1. Where can I find (on the internet) a fuse box diagram so I know what is what?

2. How do I disconnect Tele Aid?

3. Positive battery cable goes to a jumper/junction box as well as to the starter. When I disconnect main cable to jumper/junction box all drain stops. This eliminates the starter as the drain. Five lines come out of the junction box. Does anyone know where each one goes? Disconnecting one (line 1) of them dropped my amps to .5 amps. Disconnecting line 2 had no effect. Have not yet disconnected lines 4,5 and 6. Line 3 is empty. Any suggestions? (besides park it on the freeway and collect on insurance).

mleskovar

Someone posted an excellent troubleshooting procedure on this forum that takes you through the steps and explains how things work. Because all the various modules communicate with the CPU through a CANBUS the procedure is not always straightforward like you would think is normal. If it is a module causing the drain because it's keeping the CANBUS active disconnecting that module is the temporary solution but I don't know how long it takes for the CANBUS to go inactive after it's unplugged. I don't think it's immediate. My understanding is the module (or CPU) sends a 'start operation' signal and the CANBUS stays active until a 'stop operation' is received. A bad module never sends the 'stop' and the CANBUS stays active and drains the battery. Someone correct me if my understanding is wrong. Unfortunately the procedure is buried in a thread somewhere so I can't point you to it.

silver_benz

Thanks for the heads up on the canbus taking a while to "calm down". I was using the ammeter to initially connect the battery and not waiting at all.

Here is my solution.

Hooked up battery. Waited 5 mins. Connected ammeter and then disconnected battery. Still major draw.

disconnected battery
disconnected driver side seat module
reconnected battery and waited 5 mins.
Connected ammeter and then disconnected battery.
Draw dropped to 15 milliamps. Problem solved.

acedking90

Okay, before I start, I'm 16, and I drive a Benz, im not spoiled. I am literally car retarded, I don't know whats going on.

Sure enough my 2001 C240 finally crapped out on me. I replaced the battery, and everything was fine for about a whole 4 days, and again its completly dead. Now how should I pinpoint the exact problem? Is there a DIY w/ pictures? I don't know where to hook up some electronic gismo.

f*** I am so frustrated, sorry practically asking to be spoon fed.

Also, where can I unplug my seat modules to see if that is indeed the problem?

silver_benz

It seems that the "seat module" tends to go bad on these cars at an alarming rate. When they go bad, the seat still functions, but they draw all of the juice out of the battery. The batteries are pretty robust so usually it happens if the car is not driven for a day or so as the system will recharge the battery when the car is driven.

When I indicated problem solved what I actually meant was that I had finally diagnosed the root cause of the dead battery. I still have not replaced my seat module but probably will soon as the sunroof has started acted goofy since the seat module is unplugged.

Something to try:

Adjust the passenger and driver's seat where you want them to stay for a while. Look under the front of the seat. You should see a flat rectangular box with two connectors coming out of the front. Disconnect both connectors (I don't know if both connectors need to be disconnected, but this is what I did). The connectors have locking tabs at either end that need to be pinched inward to be able to work the connector loose. Either get a jump start and drive for a while to charge the battery or get it charged on a charger. If you do not have a meter or know how to use it to check amps (not volts) just wait and see if your battery goes dead after a couple of days. If not, you have found your problem. If you want to take a chance, reconnect the modules one at a time to see which one causes the battery to die.

good luck.

ML55CLA45

so.........

acedking90

Well, I said that i'm 16 so that it gives some sort of explanation to my ignorance in the car field, and that being said I quickly protected myself from the flamers by saying I am not spoiled.

ML55CLA45

why are you worried about being flamed? was someone else on this thread posting questions on how to resolve this issue "flamed?"


anyways..... are your front seats full power? most (if not all) c240s are not power foward/reverse but manual. some of the other senior members may need to correct me... but i believe that the seat controller module issue is mainly on the c320s which are full power and memory.

might want to have your alternator checked....

good luck!

-carino

acedking90

Both Driver and Passenger seats are full auto and memory, my mechanic said that it might be one of the computer systems which is supposed to shut off after thirty minutes, and it isn't, but after testing it with a light bulb, it does shut off after thirty minutes. It isn't the alternator either because the car started fine for about three days after I got a new battery put in....argh I am so frustrated, I have been without my car for nearly two weeks!


On a side note, a buddy of mine got interior, and over the license plate white LEDS for his G35x...anyone know where I can find those types from my C240?

mleskovar

I hope not

acedking90

lol okay then.

And yeah, my driver side seat module died...275 bills gone like that, on top of that my Mercedes-Benz standing star got stolen.

Chuckwagon

I recently experienced this same problem. Car was completely dead in the morning and could not even be unlocked. I noticed one night after removing the key from the car that there was a hum coming from the overhead console. I disconnected the entire unit but my battery still drained overnight.

After reading through this thread I disconnected both of the power seat control plugs located under each seat. My battery no longer drains. I thought I might get lucky and have just a single faulty control module but I verified that both are causing the battery to drain. Doesn't seem right but I'll have to replace both modules @ $275.00Ea.

Next I will tackle the false rear tail light failures reported every time I start the car. I checked all bulbs and they are fine. Sigh....

qianlimoro

Yeah.., time for that flat badge...

qianlimoro

Right. Same with my coupe. T'was the voltage regulator... Warranty, NP.

GarrettCharlton

So tell me this. Both my passenger and driver side modules are sitting on a table in my house and my car is still dying after 24 hours of no use. I would assume that a draw that kills the battery that fast would be producing some sort of heat. I have a 2001 c320 4dr with 170k miles on it.

mleskovar

You should be able to attach an external clamp on style amp meter to the main battery cable and trouble shoot it with that kind of draw. Start by just moving around wire bundles then work your way down from the big fuses closest to the battery/power source.

jaqkar

Hi guys, newbie here. I am facing a batt drain issue at the moment and finding that thread with the troubleshooting procedure will be so much help! Anyone know where it is? Could be a good sticky.

Glyn M Ruck

See my PM.

ggod001

Unplug/disconnect the seats

Gem Stater

Did anyone ever find that tutorial on the battery drain?

Gem Stater

More battery drain issues!!!! Battery will start car after overnight but, on the second day has drained and won't start the car.

My meter doesn't measure amps accurately enough to precisely measure the drain issues I am having now. I found a great YouTube on parasitic draw: He measures voltage and calculates the milliamp draw using a table from Power Probe.

I started by measuring battery voltage at 12.4 V with the car off and then started the car measuring 14.6 V across the battery. From that it seems the battery and alternator are okay.

Next I disconnected the negative clamp and - after waiting for computers to go to sleep - measured over .94 amp drain on the battery. I then used the Humble Mechanic process above and tested all the fuses in under-hood, interior and trunk fuse boxes. Zeroes on all but, 3 fuses. I measured 42mA on Fuse 42 (ABS, Instrument Cluster) 104 mA ON Fuse 57 (ESP) AND 62mA on Fuse 64 (navigation system [which I don't have]; radio). Those seem higher than a guy wants but, their total is only 208 mA - way less than a third of the 940 mA drain measured atthe battery. So, any suggestions on where to look to find the other 732 mA draw - which seems to be my real problem?

UPDATE 6-10-18: After fooling around with this problem for quite a while, I ended up getting a better meter that would accurately measure DC Amps. For me that turned out to be a must. If anyone else is trying this, it is crucial to wait long enough for all of the computers to go completely to sleep. Mine often took 10 minutes or longer to get to the final low reading which was around 780 mA. Apparently - especially when there is a problem - the computers keep talking to all of the components trying to sort things out and that takes a while before they give up. My problem turned out to be the driver's side seat controller. It moved the seat just fine. Even though I couldn't find it by measuring at the fuse (So much for Humble Mechanic), putting the ampmeter in line at the negative battery cable allowed me to see the final amp draw at 780 mA. Then it was a matter of disconnecting the most common culprits one at a time. I started with the overhead panel (of course). No change in amp draw. But, when I plugged it back in that fired up the computer again so I had to wait for it to go back to sleep. Same with passenger side seat module. When I disconnected the driver's side seat module, the amp draw dropped immediately. Since leaving it disconnected, the dead battery issues have gone away. I hope this helps the next guy who has this problem.

CodeySkate

Did you ever find out what was draining the battery?