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Battery/alt stop vehicle. Burning smell. What do I do? 2003 e320
I’ve been having issues with my car being dead after being left overnight, getting electrical consumers switched off sign a lot. replaced battery in my trunk and worked good for about a month, then decided to start dying again within this past week. Just trickle charged my battery overnight last night and I went to put it back in the trunk about 20 mins ago, at first I got electrical consumers switched off(even after charging all night) then I got the batter/alt light and no brakes light. Started smelling some burnt plastic, Did some research here and turns out burning smell is from alternator so now I’m wondering if I have to get a whole new alt or if I can just do the voltage regulator replacement? How can I test to figure out if I can just replace VR and not whole alternator? Was thinking I just had a parasitic drain draining my battery but now it’s starting to seem like it’s something else. Or maybe I have a drain and alt is bad?? Idk Already replaced my Sam and didn’t help. Really don’t have a lot of money to spend so need to know if I can do the vr diy or if I just need to go ahead and get alt. Tested my battery’s and they both are strong. Would appreciate the help a lot!
Last edited by azer carrot; 08-21-2021 at 11:10 PM.
On a 2003? Don't waste your time putting a band-aid on the problem with a fresh regulator on a worn out alternator. If you are sure that's where the problem is, get the correct alternator and install it and be done.
On a 2003? Don't waste your time putting a band-aid on the problem with a fresh regulator on a worn out alternator. If you are sure that's where the problem is, get the correct alternator and install it and be done.
yea you’re right. I’m not 100% sure if that’s the only thing that’s wrong though. Ive had battery charging issues since I’ve gotten this car. a messed up alt wouldn’t cause the battery to die from sitting overnight would it? Sorry for the stupid questions im 17 bought this as my first car and I really regret it tbh, to many electrical issues. Nice car but to much maintenance
It could drain it if it's not charging properly and fully. Rockauto plus their 5% off code should be the cheapest way to go with the new alternator. Just make sure to get the same brand and amperage as the old one.
a messed up alt wouldn’t cause the battery to die from sitting overnight would it?
Oh yes, bad alternator will most definitely drain the battery. I've had two cars that had that issue, with the first one I took off the cable from the alternator B+ post and had a multimeter between the cable and the post, there were a huge amperage draw. Second had a bad rectifier diode, and even though it started just fine, battery was dead after 20 minutes of driving and alternator was smoking hot.
So I got a new battery and alt and still with the new fully charged Battery I have “electrical malfunction electrical consumers switched off” I also failed to mention that I had bought an aftermarket converter scoshe harness for my touchscreen radio and aftermarket amplifier and all was good for like 6 months then the malfunction error came up for awhile but the radio still worked for a few months until it stopped working. The harness is no longer plugged up but Sometimes when the car is off I’ll hear weird static/static popping noises coming from the speakers or around the canbus area around the passenger seat. I don’t know if this is the problem or not just mentioning it. Really frustrating someone please help me out
Did you replace the alternator with a Bosch alternator? I have heard reports that the car does not like non-Bosch alternators. Or even a non-Bosch voltage regulator put into a Bosch alternator may not work.
Did you replace the alternator with a Bosch alternator? I have heard reports that the car does not like non-Bosch alternators. Or even a non-Bosch voltage regulator put into a Bosch alternator may not work.
I got a remy alt. $180. I checked the front battery once it was at 11 something volts but I didn’t check good cause I heard the front battery was only for brake system in case rear battery goes out? And I haven’t messed with any voltage regulator
Update* checked my small battery and it’s at 12.8 v and my brand new rear battery that sit in the car overnight is at 12.4v. I have a moltmeter but I don’t beleive it has mah so I can’t check where it’s draining from. Any ideas please? How do I check if the bcm is good/if it is the issue?
Okay another update, i tried driving it yesterday and I got the red battery saying visit workshop while driving for the first time ever…then about 5 mins later it said battery/alternator stop vehicle. Keep in mind I just put fresh battery and alt in here. Then another 5 mins later it said brakes aren’t working stop vehicle and there was a constant beeping noise with it. The brakes were still working fine and I drove for about 10 mins with the warning on until I got home and nothing happened. The alternator is on there properly I drove the car fine for a few days when I first put the alt and new battery in. I’m really lost and idk what to do so I bought a bcm box and it’s otw so hopefully that’s what it is. Also, the brand new battery died after letting sit overnight after changing the alternator battery and Sam in the trunk. I really don’t know what to do I’m about to sell this piece of ****
Last edited by azer carrot; 10-02-2021 at 03:21 PM.
Okay another update, i tried driving it yesterday and I got the red battery saying visit workshop while driving for the first time ever…then about 5 mins later it said battery/alternator stop vehicle. Keep in mind I just put fresh battery and alt in here. Then another 5 mins later it said brakes aren’t working stop vehicle and there was a constant beeping noise with it. The brakes were still working fine and I drove for about 10 mins with the warning on until I got home and nothing happened. The alternator is on there properly I drove the car fine for a few days when I first put the alt and new battery in. I’m really lost and idk what to do so I bought a bcm box and it’s otw so hopefully that’s what it is. Also, the brand new battery died after letting sit overnight after changing the alternator battery and Sam in the trunk. I really don’t know what to do I’m about to sell this piece of ****
Your car maintenance is not doing real well it seems...
Fixing things right does not need to be difficult. The 1st rule is to not break more things than you fix and TEST what you've just fixed to see that it is working.
Changing a bunch of parts with a wet finger can quickly get expensive. Sometimes its the only way but not the best choice.
I see couples issues in your story....
1- You need to scan your OBD2 to figure what exactly your computer modules are reporting.
2- You need to test live voltages to figure what your alternator voltage is doing.
With electrical equipment it's best to use a DVM for testing than go by smell alone!!
Learn one step at the time at your own pace and based on your goals.
3- Your R-SAM likely needs to be SCN coded and is the module triggering countless FAULTS and causes your battery to drain by not going to sleep.
SAM computers are to car power what ECU is to the engine.
Last edited by CaliBenzDriver; 10-06-2021 at 06:48 PM.
Your car maintenance is not doing real well it seems...
Fixing things right does not need to be difficult. The 1st rule is to not break more things than you fix and TEST what you've just fixed to see that it is working.
Changing a bunch of parts with a wet finger can quickly get expensive. Sometimes its the only way but not the best choice.
I see couples issues in your story....
1- You need to scan your OBD2 to figure what exactly your computer modules are reporting.
2- You need to test live voltages to figure what your alternator voltage is doing.
With electrical equipment it's best to use a DVM for testing than go by smell alone!!
Learn one step at the time at your own pace and based on your goals.
3- Your R-SAM likely needs to be SCN coded and is the module triggering countless FAULTS and causes your battery to drain by not going to sleep.
SAM computers are to car power what ECU is to the engine.
Okay, I was told by the eBay seller that I purchased my rear Sam from that it will code itself and it doesn’t require coding, even after I told them what you said. The bcm I ordered last week came in and I put it in my car and it didn’t make a difference lol battery still drained overnight. Finally got a multimeter that allows current draw test so I tested for mA and it’s only pulling 14-17mA? It shoots up to 115mA when I hear the airbags blowing up in my car but then promptly goes back down to the same range. So it doesn’t seem to actually be a parasitic draw since it’s steady below 50mA? I guess I will get a Benz star diagnosis of AliExpress soon if I can’t figure out my problem. There is not a big draw so I can’t comprehend why it’s dying overnight? I cannot bring it to a shop I’m only 17, no insurance, no Id, and closest benz shop is in Raleigh which is 2 1/2 hours from me. Idk what to do I just wanna get my first car running properly so when I get my license I’ll have a nice car to drive
Getting a Xentry system is a great step in the right direction. It will tell you what module is staying awake and what modules are reporting faults.
Get an Amp-clamp for drain watch:
Normally you want to use a "DC Clamp meter", not a 10AmpMax serial amp meter (the base currents are between 20 and 40Amps on these cars) - Don't mess with good high-Amp car connection wherever you see a fat cable... just use your clamp!
That being sayed 17mA is not going to drain your battery overnight. Something else is doing it...
Okay I bought a obd2 scanner. It’s not a xentry but it was $300 off Amazon. Where do I start now?I’m kind of lost on what to do next. Heres the codes it’s throwing-
Congratulations on your fine purchase of this scanner.
Now you can clearly see that only THREE MODULES are reporting to work and all of them are loaded with errors.
cluster gateway fault
To fix that concentrate on your instrument cluster first. This module acts as a gateway for other network modules.
You won't see other modules until IC is back on the network.
okay so do you think I just need to buy a whole new instrument cluster? Or do you think this is fixable? Also thank you for replying to me again I really appreciate it
okay so do you think I just need to buy a whole new instrument cluster? Or do you think this is fixable? Also thank you for replying to me again I really appreciate it
MB parts need to be coded with special procedure which you can not do, right?
Hopefully your cluster does not need replacement.
Be sure to..:
check on its wiring...
power supply: fuse/GND...
it's connection to ECU...
The question to answer is... :
"Why is the IC not communicating?"
I don't think it is using "solderless pins" at the connector socket.
Last edited by CaliBenzDriver; 01-12-2022 at 02:45 PM.
MB parts need to be coded with special procedure which you can not do, right?
Hopefully your cluster does not need replacement.
Be sure to..:
check on its wiring...
power supply: fuse/GND...
it's connection to ECU...
The question to answer is... :
"Why is the IC not communicating?"
I don't think it is using "solderless pins" at the connector socket.
Okay I have figured out the draining issues. Pulled out fuse #34 (Driver-side front seat adjustment control unit) and fuse #40(Audio gateway control unit) and my draining issues have stopped. I’m no longer getting battery/alternator fault, however I do have “electrical consumers switched off” and “visit workshop”. Tested my front battery and it’s bad, only was at 8v. Someone told me it’s only for sbc so don’t think that’s the issue but I’m going to replace soon.My instrument cluster appears to work fine so I don’t understand why it’s throwing codes. Before I got a diagnostic system I bought a new bcm aswell as a rear Sam off eBay and installed myself just because I was desperate to solve this, wondering if this could be the issue? I have been driving the car and everything works fine, besides my radio(with audio gate fuse in) which really sucks cause I paid $400 for the aftermarket head unit harness and bought subwoofers and got barely any use out of them. Could it be the 150 fuses in the junction fuse box? I used to jump the car from that location occasionally and wondering if it’s possible I fried it.
You need to get back to a normal voltage range to expect any of your computers to work.
Getting to 8V is likely the threshold when the systems quit... so the drain happened to stop there. Voltage for car computers is needed like gasoline to run the engine.
Pulled the seat fuse:
Now take a quick look at your seat module... bad connections and oxidation can cause your drain. In a pinch unplug its connectors during testing.
Progressing:
- Once you get a good battery voltage (12.6V and up) your "consumers" should normally get enabled again
- Clear faults
- then do a power-reboot
- then scan again to get a clean slate about what's going on.
- Still 3 modules only or nearly ok??
Battery tips:
Unplugg your battery when car is not in use will help prevent discharge. Use a tender ok as well.
Try NOT to rely on your car charhing system to charge a flat battery after jumping it.
✌️
Last edited by CaliBenzDriver; 01-20-2022 at 06:19 PM.
Okay, well the draining issues have only stopped while the car is not on, it won’t die over night anymore. However, when I turn the car on the with volt meter attached the battery voltage fluctuates very randomly and the battery is being drained. Once I turn the car off the battery voltage begins to go back up. I put back in my original rear sam and bcm but the same issue occurs. I haven’t replaced the front battery yet because I figure there is no need to if my rear battery is draining while the car is on. I’ve already replaced alternator so I’m still very lost in what the issue could be.
...
However, when I turn the car on the with volt meter attached the battery voltage fluctuates very randomly and the battery is being drained.
Once I turn the car off the battery voltage begins to go back up.
....
can you expend a bit on the above quote?
What sort of voltage range are we talking about for your random drain: above 11.0; 12.0; 12.6; 13.5; 14.4...?
Burning smell:
Have you had a look at BCM internals??
Last edited by CaliBenzDriver; 01-25-2022 at 05:33 PM.
In this video the battery was at 12.5 before I started car then it dropped to like 11.9 when car started then it went back up to 12.01 before the fluctuation began, one point in the video it dropped all the way down to 10 volts so something is really draining it heavy. the burning smell im 95% sure it was coming from the front of the car so no I didn’t open up the bcm, when i thought the bcm was my issue I just bought a whole new one because someone told me the bcm is hard to repair if you aren’t experienced
When I was looking for if my car still had a battery drain issue, I had negative cable disconnected from the battery, and I had a 70 watt halogen bulb connected between the negative battery post and the negative cable. When the circuit was connected, light bulb was very bright for a few seconds, the went to dim as the modules went to sleep. So dim that I could barely see it. So there were nothing draining the battery, but if there would've been, I would pull the fuses and see which circuit is the culprit.
In this video the battery was at 12.5 before I started car then it dropped to like 11.9 when car started then it went back up to 12.01 before the fluctuation began, one point in the video it dropped all the way down to 10 volts so something is really draining it heavy. the burning smell im 95% sure it was coming from the front of the car so no I didn’t open up the bcm, when i thought the bcm was my issue I just bought a whole new one because someone told me the bcm is hard to repair if you aren’t experienced
So your battery voltage is around 12 volts when the engine is running? Then you have a bad alternator. I've had cars with alternators that have drained the battery, and they had burning smell.
edit/ Just read previous posts, and you should have a good alternator.
08-21-2021, 10:53 PM
