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Discussion Starter #23
What a pisser, woke up to the sound of dripping on the bedroom ceiling - busted my big toe trying to solve this leak from water tank in attic. Life's a bitch, sometimes when shit comes in wave after wave like this

Anyway, tested fuses with the recommended method: connected the battery, left it for 45mins to settle, tested across each fuse - fuses 24 & 25 had non zero voltage drop across them - something like 60 or 70mV each

These fuses relate to the PSE unit which is disconnected so something amiss with the wiring going to this unit?

It doesn't explain the large current draw of 700mA across connectors to battery but I have to test this again - I tried to put multimeter in series with battery & set to current reading but current too high to read.The bench supply across these terminals shows a settled current draw of 700mA from an initial 1A. This implies other circuits not on the fuses are drawing the major current. I'll check alternator connection.

Any other suggestions to check?
 

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Registered 1997 SLK230 Kompressor
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End of this article.. parasitic drain testing caused by starter or alternator issues? Why Does My Car Battery Discharge Overnight or When Parked?

And don't remind me of tanks in ceilings. I had one in a very old house in the UK that split when I was off on my business travels. My wife was not happy. I found it very difficult explaining to anyone in Europe why a tank in the ceiling should be necessary. Bit akin to drawing water from a well. But it was then at least easy to explain why there were two taps in every sink and why the showers were crap.:rolleyes:
 

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Discussion Starter #25
Checked AC voltage across battery while car is idling - it is 14mV jumping to 20mV intermittently
Does this seem OK?

I'm off to exchange my UK driving license for an Irish license before Brexit kicks in ;)
 

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Registered 1997 SLK230 Kompressor
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Possibly/probably not?
The article says zero volts on your lowest AC setting. You need a comment from someone who knows more than I do. My last failed alternator just wouldn't charge and it was obvious it was faulty.
However if you need to replace, it doesn't seem too difficult
 

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Check all fuses first, then un-fused circuits (Starter, alternator)

I know you have r170, On r172 there is a junction box for un-fused power wires under the hood. Which actually has large fuses.
On my r172 it was the alternator diodes when they were hot that was causing a drain.
Car can take 20 to 30 minutes to sleep properly

Good Luck
 

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Discussion Starter #28 (Edited)
Thanks, my battery is charging up properly - voltage from alternator is 14.?V AFAIR
I will look into those other non-fused circuits.

I did let it sleep for 30 mins before testing V across the fuses
I may need to put it into electrical car specialist as busted big toe doesn't add to my enjoyment of SLK ownership DIYing :)
 

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Registered 2006 Slk280
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Something I can't find in a manual is the current draw from the battery when the ignition is completely off.

I suspect I have an excessive current drain which is draining my battery overnight on an '03 R170 SLK. It is stock with no add-ons so current drain should be roughly the same as all other same models

When I disconnect the battery & put a 12V PS on the car leads I see a 1Amp draw quickly dropping to a steady 0.7A draw

This would seem to be excessive as it means a 70amp hour battery would delete in 100 hours. My battery is not drained overnight but depleted enough that car won't start. I reckon the Platinum Prestige Heavy Duty 3 year old battery is probably weak but before i change it any help would be appreciated as putting in a new battery is just a bandaid
There should be zero current draw when your key is off unless you have a security system engaged......but that shouldn’t be enough to drain your battery. Did you have something aftermarket installed? Is the battery too weak only to start the vehicle? Does other accessories work in the mornings? A bad battery will not hold enough charge to start the vehicle even though it will power the accessories. It requires quite a bit of current for the starter that the battery may be too weak to supply. How long has this been going on? Weeks? Months? Days? Do you drive the car on a regular basis?
 

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Discussion Starter #30
Thanks Slksmitty

I have a new battery coming tomorrow so will check it all out tomorrow
I may not have left it long enough to check the draw on the battery when I attached the 12V bench supply - I saw it go from 1A to 0.7A within a couple of minutes but I should have left it on for 30mins or so to get the real at-rest current draw.

I have a PSE unit & rear wheel speed sensors coming from Germany next week.
Damp/water is the problem with in the failure of the PSE & speed sensors. The speed sensor connectors are in a rubber cup that is inserted into the underside bodywork- this cup collects water inside the bodywork & causes these speed sensors to send wrong signals. I'll be trying to solve this with the sensor cups & will be putting the PSE unit in a plastic bag with desiccator bag to keep it dry
 

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I had the same issue with my 07 slk55amg. It ended up being the alarm system being on all the time but never made any sounds! Had it replaced and battery has been good ever since.
 

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Discussion Starter #32 (Edited)
Well, I did another test with my bench supply set to 12V & connected across battery leads (battery disconnected) & lo & behold, current leakage starts at 143mV & settles to 8mV after a short while i.e no current leakage

The only thing I changed between the start of this thread (high current drain) & now is that one of the speed sensors had a botched repair job done on the wiring to it - the connectors in the cup had been cut off & wires soldered together with insulation tape wrapped around them, instead. I suspect that because this botch was in the rubber cup that enters the body work & the inside of this cup was damp/wet, that this was causing a current drain?

I replaced the bodge by soldering the wires & using a tight heatsink on each soldered wire to seal it from any intrusion of damp/water & kept them separated, anyway.

So looks like my problem might be sorted & my ABS/ESP lights might be sorted too if I can reset these errors?

I have a replacement PSE unit & two rear speed sensors coming & also received a new battery today - so now I have a spare good? battery which I was thinking of using it in the boot to power a dehumidifier unit as this damp/water is the most common SLK problem. Has anybody done this? I know it will require recharging the battery running this dehumidifer & this will depend on how good this 3 year old battery is - I will put a known current drain on this battery to check its health before I invest in an electronic dehumidifier - otherwise I'll use the silica gel dehumidifiers?

Problem is my SLK is always parked in the driveway overnight (no garage) & wet Irish winters (often Irish summers) means a dehumidifier will be working overtime (there maybe boot seals that need attending to?). Anybody got experience of dehumidifiers in these conditions?
 

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Premium Member 2005 SLK55 AMG; 2005 SLK350
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I've never heard of anybody using a dehumidifier in the boot. It's possible to keep the boot dry: replacing the seal around the center high stop lamp, cleaning and treating the seals, and ensuring the drains aren't clogged is usually enough from what I've seen. Keep in mind there is a drain under the spare tire that's supposed to keep water from accumulating there.

And don't forget the mod to invert the PSE (so that in case of flooding the circuit board isn't the first thing to go).
 

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Discussion Starter #35
I've never heard of anybody using a dehumidifier in the boot. It's possible to keep the boot dry: replacing the seal around the center high stop lamp, cleaning and treating the seals, and ensuring the drains aren't clogged is usually enough from what I've seen. Keep in mind there is a drain under the spare tire that's supposed to keep water from accumulating there.

And don't forget the mod to invert the PSE (so that in case of flooding the circuit board isn't the first thing to go).
Yea, the dehumidifier in the boot using something like a low current peltier dehumdifier was just an idea to use the spare 12V good? battery that I now have on hand?

Sure, I'll check/replace/clean seals, clean drains. I've already attended to the drain under the spare wheel as a lot of water was accumulating in the boot.

Any hints how to check where water might be getting into the boot? Something that can identify specifically where it's coming from along the seals?

But the rubber cap in the underbody that the each rear speed sensor wires run through also gets damp/wet *fills with watre?) & this seems to be coming from within the body itself, not the boot?
 

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Registered 1997 SLK230 Kompressor
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Don't put a battery in the boot!!
Might be OK if it is a gel type but otherwise you will get acid fumes which will really rot things out. I had issues with corrosion on both an XJS and BMW 540 which had had their batteries improperly replaced.
 

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Premium Member 2005 SLK55 AMG; 2005 SLK350
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I use talcum powder to learn where seals are leaking. Also you can put newspaper down. If you have water in the boot lid itself you should address the seal around the center brake light and, for pre-FL models, around the keyhole. Either a new seal or add sealant.
 

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Discussion Starter #39
Just to report back on this - the PSE unit arrived & works perfectly except for one thing - boot doesn't lock, doors do
I wonder might this be caused by having to manually unlock the open booth at one stage? I'm pretty sure it was working before & don't believe I disturbed the vacuum tube in the boot. I'll look into it

I also discovered that my battery was weak as well as having a short caused by wetness getting into the rear speed sensor. With the new battery, car seems to perform smoother - there was a bit of chugging when starting from cold but now it seems to be gone.

Also got some replace struts for the boot & now don't have to worry about it slamming on my head.

Still got a number of problems to sort & spent €270 for PSE unit + struts & €120 for a very good battery but saved myself a lot of money by finding the short myself
 

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Discussion Starter #40 (Edited)
I spoke too soon - the battery drain problem is back
I thought I had fixed it but seems I haven't - it must be something related to water causing an electrical short as I measured low current leakage after I sorted out the botched wiring on one rear wheel speed sensor.

I then thought I had a bad battery as I had a dead battery overnight but it must have been the current leakage issue again draining the battery?

Thinking it was a bad battery, I replaced it & new battery disguised the current leakage problem for a week or so but went to start the car after it was sitting in driveway for 2 days & it's a dead battery

So back to the beginning to trace where the short is along with all my other SLK problems!!
  • Have to figure out why the boot is not locking with the replacement PSE unit I installed - everything else is locking on the remote & the PSE unit is the exact same model number
  • Replaced the boot lid struts
  • About to replace the 4 rubber stops which were all split, probably because the boot slamming from the struts not working?
  • I noticed the interior lights were not turning on & took out this unit - this may be where the short was coming from, not the speed sensor, after all - who knows at this stage - not me?
  • I need to find out how to replace the clear plastic lens strip which covers the indicator on the right wing mirror - it broke against a pillar when reversing out of a car space & I can't see any easy way to reattach/glue it in place.
Last time I was trying to fix the car, I busted my toe - today I jumped away from what I thought was the noise of shorting sparks - did so in a strange way & pulled one of my pectoral muscles - pretty damn sore

FFS, I'm not in love with this car - it injures me every time I try to fix it :mad:
 
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