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I'm hopeful that someone here can intervene with some advice before I aim my 2004 E500 4matic wagon off a cliff. I've had on-going and randomly recurring electrical issues and am simply at my wits end.
1. The battery randomly dies. It's been to an independent shop and the dealer with this issue. Main battery replaced. Aux battery replaced. Charging system checked multiple times with no issues. Tested multiple times for phantom electrical draw - nothing. On the advice of one of the forums I did bypass the seat control module under the passenger seat (apparently a common draw issue) but with no effect. I've also replaced the alarm module as I understood that might be an issue (and the alarm was acting up with random false alarms which were solved with the replacement of the module). Sometimes the battery will stay charged for days - or weeks - sometimes it needs to be jump started after having a door open with the dome light on for less than two minutes. This is all beyond frustrating!
2. Occasionally - not for the last couple of months but suddenly three times in the last 24 hours - when I open the driver's door the tailgate automatically lifts to the fully open position. Yup - the act of opening the door (not unlocking it with the remote - just physically opening the door) causes the tailgate to automatically open. Once its open one has to manually close it - the auto close button function is completely inoperative. But, if the tailgate is opened on purpose (with there emote or the rear exterior latch) the power close function works fine.
3. This hasn't happened in a few months but is again a random recurring issue - the tailgate will open on its own. Car in the garage overnight and in the morning the tailgate is wide open. Or, drive to the store, lock the car, walk out into the lot 20 minutes later to find the tailgate wide open. Again - hasn't happened in months but when it does happen it seems to happen for a week or so and then the issue somehow self-resolves for a month, or two, or six.
In addition to replacing the alarm module and bypassing the seat controller I have also done the "disconnect the battery overnight" reset that seems to be often suggested for electrical issues. No permanent help. Again - dealer can't find any issues. Indy can't find any issues. Additionally, I have replaced all of the batteries in the key fobs in case some of the issues were related to a low battery issue there. Hopefully someone here is smarter than all of us combined to help me preserve my sanity and get this car back to the status of reliable transportation (because I absolutely love the car otherwise).
Last edited by res94025; 01-04-2021 at 04:34 PM.
Reason: adding information
Check wiring in door boot. Fine, long shot and not sure why no fault codes are stored but door control module could be causing drain which incorporates interior tailgate switch wiring – f33 @ interior fuse panel. Try replacing module with original part # 2118200526 about $20 or so used with free shipping on ebay. FYI here are compatible part #s
I'm hopeful that someone here can intervene with some advice before I aim my 2004 E500 4matic wagon off a cliff. I've had on-going and randomly recurring electrical issues and am simply at my wits end.
1. The battery randomly dies. It's been to an independent shop and the dealer with this issue. Main battery replaced. Aux battery replaced. Charging system checked multiple times with no issues. Tested multiple times for phantom electrical draw - nothing. On the advice of one of the forums I did bypass the seat control module under the passenger seat (apparently a common draw issue) but with no effect. I've also replaced the alarm module as I understood that might be an issue (and the alarm was acting up with random false alarms which were solved with the replacement of the module). Sometimes the battery will stay charged for days - or weeks - sometimes it needs to be jump started after having a door open with the dome light on for less than two minutes. This is all beyond frustrating!
2. Occasionally - not for the last couple of months but suddenly three times in the last 24 hours - when I open the driver's door the tailgate automatically lifts to the fully open position. Yup - the act of opening the door (not unlocking it with the remote - just physically opening the door) causes the tailgate to automatically open. Once its open one has to manually close it - the auto close button function is completely inoperative. But, if the tailgate is opened on purpose (with there emote or the rear exterior latch) the power close function works fine.
3. This hasn't happened in a few months but is again a random recurring issue - the tailgate will open on its own. Car in the garage overnight and in the morning the tailgate is wide open. Or, drive to the store, lock the car, walk out into the lot 20 minutes later to find the tailgate wide open. Again - hasn't happened in months but when it does happen it seems to happen for a week or so and then the issue somehow self-resolves for a month, or two, or six.
In addition to replacing the alarm module and bypassing the seat controller I have also done the "disconnect the battery overnight" reset that seems to be often suggested for electrical issues. No permanent help. Again - dealer can't find any issues. Indy can't find any issues. Additionally, I have replaced all of the batteries in the key fobs in case some of the issues were related to a low battery issue there. Hopefully someone here is smarter than all of us combined to help me preserve my sanity and get this car back to the status of reliable transportation (because I absolutely love the car otherwise).
01-04-2021, 04:18 PM
