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I have a major electrical problem over the last few days.
On Thursday, I had numerous false warnings about the SRS, brake wear, bad right headlight, and alternator. I figured I'd have a look at the forums and see if there was something I could do. Well Friday night as I reviewed the forum the right hand head light came on. It would not turn off regardless of the switch position. As mysteriously as it came on it went off, a few hours later it was back on and stayed on till the battery went dead.
So between rainstorms today I put on the charger so that I could open the tailgate and put it in neutral so I could have towed. Next thing I notice is that the rear windows have rolled down on their own. I could roll up one side but it kept going down on its own like it was detecting something stuck in the window.
Well the car is tarped and I thought at least the headlight is off. He we are an hour later and the headlight is on.
I cannot see a way to turn off the headlights from the "fuse map" It didn't seem like a good idea to unplug the ignitor while it is on.
Any ideas about the over all issue or instructions on how to kill the headlights?
First thing is to kill power to it and figure out if your battery is good or not. Next is to check throughout for water intrusion. If you had a water leak into the interior, you could have some shorts or worse, corrosion.
Just know, a low battery can cause all kinds of strange computer module behavior.
The fuse map doesn't identify a fuse for the headlights and the relays are not identified, so other than random pulling I cannot tell what should be unplugged.
I looked for water intrusion; the airbox at the cowl was damp but the drain is functional, no evidence of water inside. We also have rubber mats to keep moisture from shoes getting muddy; I also checked the spare tire well and there was no water there.
When I began to charge the car the back windows started to go up and down on their own, so you can add that to the list of sensors that are related to the problem. Also there appears to be no output from the stereo, although the head unit appears to be working.
I was hoping with the assortment of warnings:
SRS, brake wear, alternator, auto headlight failure, headlight coming on, and now the windows going up and down and no sound from the stereo would point to a specific area to look for damage.
I think that the car may still have the original battery, but I have had no problem with it starting or other signs of a failing battery.
The front has false floors. Remove some trim,pull the carpet back to access the "floorwells" on each side.
Battery(s) are on passenger side and the stereo equipment on drivers side. Check those and see if you have water.
The fuse map doesn't identify a fuse for the headlights and the relays are not identified, so other than random pulling I cannot tell what should be unplugged.
I would disconnect the battery, as stated above.
I looked for water intrusion; the airbox at the cowl was damp but the drain is functional, no evidence of water inside. We also have rubber mats to keep moisture from shoes getting muddy; I also checked the spare tire well and there was no water there.
Air box being wet is a bad sign... maybe. Since you know where to look, rip that rubber drain out all together. It may have been restricted and slowly drained out, but not before letting water in. Trust me when I say get it out.
When I began to charge the car the back windows started to go up and down on their own, so you can add that to the list of sensors that are related to the problem. Also there appears to be no output from the stereo, although the head unit appears to be working.
I was hoping with the assortment of warnings:
SRS, brake wear, alternator, auto headlight failure, headlight coming on, and now the windows going up and down and no sound from the stereo would point to a specific area to look for damage.
I think that the car may still have the original battery, but I have had no problem with it starting or other signs of a failing battery.
A failing battery many times believe it or not can still start the car. Used to see this all the time in the Jaguar world.
Seriously check for water. Are the cabin filters wet? That would be one sign. Like ghenry stated, feel around the carpets for water too. A good and bad feature of our cars is that there is a false floor in it that houses electronics. Good in that it keeps them in a protected environment. Bad in that if water gets in the cabin..... well we all know what happens with water and electronics.
If you didn't get water in the cabin I would seriously lean towards it being the battery. Especially if all the stuff failed suddenly and worked fine before..
I would see Jag guys get a page of OBD codes... and have them all go away once they replaced the battery. All without the car ever having trouble starting.
I decided to get a new battery. My smart charger stopped several times giving various errors. I don't really know if the errors are related to the battery or the power fluctuations with the lights flashing on and off. Since everything is erratic at the moment I don't know if I will be able to access the battery without removing the seat, so I figured after 8 years it may be time for a battery and if I have to take it apart I might as well be prepared to put a new one in. I got a Bosch Platinum AGM from PepBoys, if you order online there is a 20% off coupon and I could get the battery same day.
I looked again carefully and did not find any water in the car, although it appears that the panoroof could leak with out getting the carpet wet. The dampness in the cowl drain was related to the rainstorm that was occurring while I was trying to fix the car.
If the battery doesn't fix it, then I guess I'll be pulling out the carpet to get to the foot wells and see if its wet in there. If it needs to go to the dealer at least I wont have to pay them for a new battery and installation.
Well I got the original factory battery out; it was leaking around the negative post. In addition I also found 5 gallons of water. The carpets were dry, so I guess I will be busy on a hunt to find the water leak as well as drying and cleaning all the components.
So here is what I posted in the other thread you were in....
Ewwww... So, highly suspect the water came in from the air box. Even if the intake box was clear of water you need to think of it like this... the rubber check valve in the air intake box only allows so much water to run out. Over time debris can slow it down more.. so even though it is draining, a lot of flow can overwhelm the drain and the box starts to fill until it dumps into the climate control air box... once that fills it flows out, behind the carpet and fills the floor wells.
Rip that rubber piece of "poo" out. I can put a garden hose in the air box at full clip and the water doesn't back up...
As said above... the other place to check are the drains in the roof channel. That is an easy test. Get something like a small watering can with a spout. Pour a little water in the channel by any drains.. you should see the same small amount of water puddle on the ground under the car like when the A/C is on.
But again... I highly suspect the first scenario. These cars are tight and have never seen concerns about window seals or anything...
Oh yea... something I discovered when mine got a little wet... the battery drained because the blower would stay on... once I cleaned everything up and changed the cabin filters it stopped. It was as if it was trying to dry itself out.. LOL
I was lucky because only a little got in. Not enough to flood it.
There are 2 silver clips on that cover . Unclip them and pull the cover straight up. Look in the botton of the cabin filter box .Where the three tabs and the locater tab(longer tab) engage in the bottom of the box you'll see the valve.
PULL IT OUT! Run some water thru it to make sure it clear of mung etc.
Last edited by ghenry; Nov 6, 2015 at 08:24 PM.
Reason: Clarification
Between rain storms I was able uncover the car and work on getting the front carpet up. I found another 1/2 gallon of water. The front SAM was half way submerged.
I working on getting the car dried out. Since I gone through all this trouble to gain assess, I may as well change the backup battery as well.
I checked by air box and the grommet had been removed. Just looks dusty like Marc's. The cabin filters were also dry.
Once I get the SAM out, I'll see if that compartment drains to the battery compartment. It appears that it may based on the water levels.
I'm going to check the A/C drains. The water was so nice and clear, I wonder if it was condensation rather than rainwater.
Interesting that the SAM is also called the Mercedes Anti-Theft Alarm Control Unit. I found one at a local wrecking yard for $150 or new ones for about $325. Hopefully, Ill be back on the road soon.
Josworth had mentioned this to me but forgot to look for it but the pictures attached made it easy to locate. Mine had also been removed, nice and dry in there.
Between rain storms I was able uncover the car and work on getting the front carpet up. I found another 1/2 gallon of water. The front SAM was half way submerged.
I'm going to check the A/C drains. The water was so nice and clear, I wonder if it was condensation rather than rainwater.
Interesting that the SAM is also called the Mercedes Anti-Theft Alarm Control Unit. I found one at a local wrecking yard for $150 or new ones for about $325. Hopefully, Ill be back on the road soon.
Holy Moly.... that is a lot of water...
Since the water is "clean" and there is a lot of it I would suspect it is a weather leak and not condensation overflow from the A/C. It takes weeks for my basement dehumidifier to pull a couple of gallons out of the air. I would suspect A/C drainage to be musty and stagnant looking. That said, you can't rule anything out at this point and definitely check it.
Did you check the sunroof drains? Also, since you are pulling stuff apart anyway, keep a sharp lookout for what I call "traces". Looking carefully you will find lines in the dust that show the path the water is taking.. follow those paths to the leak...
If you look at the bottom portion of Marc's picture of the air intake box you will see water lines. That is what I am talking about.
Also, be sure to pick up a couple of cans of contact cleaner and a good size tube of dielectric grease. Where you disassemble
unplug every connector, clean it with contact cleaner (it will displace moisture and dry residue free) then dab some grease on the pins or sockets of the connectors and reattach. The grease will prevent corrosion at the electrical contact point.
It can get ugly.... leaks are very hard to find. The vehicle I had before was a Jeep Liberty... the last straw was when I was following leak traces and it lead to the weld seams of the roof... Literally leaking in from the roof and running down the pillars.... And it was NEVER hit.... I will never buy a Jeep again... and that was my third...
I gladly took the $4,000.00 loss to dump that P.O.S.
Last edited by josworth; Nov 10, 2015 at 08:11 AM.
Reason: Clarity
I think I found the source of the water. This drain piece was not properly attached to the body and was filled halfway with debris.
That nub on the drain is supposed to plug into that hole in the body above the oval plug. It wasn't and when the drain overflows it would go down the hole.
That is the hole where water was going.
The end of the drain fits into a hole near the bottom of the cabin air intake.
It rained last night and I left the car under a tarp; all but the cowl was covered and there was new water in the foot well, maybe a cup or two. It looked like it had been flowing over the foil patch closest to the firewall. The days before I had dried all this out and then packed the area with towels to absorb water from the carpet padding.
After letting it drip dry for a few days, I decided to put in the new battery and see if it would start, it did and now its in the garage. Now I can get in there and get a space heater blowing on the area.
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