CLK55 W209 Charging Fault

[danielfoley]

Hi. I have a 2003 w209 CLK55.

I brought it back in October. It was water logged when I brought it (condensation). Anyway, back in January I was driving and got the visit workshop warning with the battery icon.

Changed the alternator with a LUCAS alternator. Still got the warning, 11v at the battery.

Changed the battery with a 110ah YUASA battery.

Still getting the warning. Checked battery with engine running, only getting 10.5-11v.

To check alternator I ran a jumper cable from back of alternator to battery when engine running and got 13.5v and the warning icon vanished so I know the alternator is working.

So, somewhere between the alternator positive and battery there is a fault? I've struggled to find out what it could be, I found a post mentioning an x4 unit? Apparently there is another interim fuse in the cabin under the carpet somewhere, but, I can't find where it is. I've ripped out the passenger footwell and I can see live cables but no unit?

Really struggling with this. Tempted to run a new live direct from alternator to prefuse box under bonnet.

When I took the carpet out the floor underneath was absolutely full of water.

 

[danielfoley]

Hi. I have a 2003 w209 CLK55.

I brought it back in October. It was water logged when I brought it (condensation). Anyway, back in January I was driving and got the visit workshop warning with the battery icon.

Changed the alternator with a LUCAS alternator. Still got the warning, 11v at the battery.

Changed the battery with a 110ah YUASA battery.

Still getting the warning. Checked battery with engine running, only getting 10.5-11v.

To check alternator I ran a jumper cable from back of alternator to battery when engine running and got 13.5v and the warning icon vanished so I know the alternator is working.

So, somewhere between the alternator positive and battery there is a fault? I've struggled to find out what it could be, I found a post mentioning an x4 unit? Apparently there is another interim fuse in the cabin under the carpet somewhere, but, I can't find where it is. I've ripped out the passenger footwell and I can see live cables but no unit?

Really struggling with this. Tempted to run a new live direct from alternator to prefuse box under bonnet.

When I took the carpet out the floor underneath was absolutely full of water.

 

[peterws1957]

Hi. I have a 2003 w209 CLK55.

I brought it back in October. It was water logged when I brought it (condensation). Anyway, back in January I was driving and got the visit workshop warning with the battery icon.

Changed the alternator with a LUCAS alternator. Still got the warning, 11v at the battery.

Changed the battery with a 110ah YUASA battery.

Still getting the warning. Checked battery with engine running, only getting 10.5-11v.

To check alternator I ran a jumper cable from back of alternator to battery when engine running and got 13.5v and the warning icon vanished so I know the alternator is working.

So, somewhere between the alternator positive and battery there is a fault? I've struggled to find out what it could be, I found a post mentioning an x4 unit? Apparently there is another interim fuse in the cabin under the carpet somewhere, but, I can't find where it is. I've ripped out the passenger footwell and I can see live cables but no unit?

Really struggling with this. Tempted to run a new live direct from alternator to prefuse box under bonnet.

When I took the carpet out the floor underneath was absolutely full of water.

I would have thought that if the interior was waterlogged it would be unlikely down to condensation alone. The condensation may very well be caused by a water leak, which would have to be traced. I'm not familiar with the CLK, but wonder whether you have a blockage in one of the drains, particularly on the bulkhead. (on my CL there are 4 drains on the bulkhead and 3 in the wiper scuttle - if even 1 blocks, it overflows and water can enter through the bulkhead). I firstly would be investigating the water ingress. As a temporary measure I'd be putting those plastic containers filled with damp absorbing crystals into the interior.( Buy from Screwfix). Very effective at moisture control. I wonder whether an earthing point has corroded to cause the problem with charging. An wiring diagram might be useful in checking a potential fault. Sorry can't be more helpful. I'm sure others will chime in.

 

[Blobcat]

As per above, I expect the scuttle drains (or sunroof drains (if it has one)) are blocked.

 

[Wearsafoxhat]

I’d look at the scuttle drains too. Our 208 ( don’t suspect that the 209 is much different in this design) used to get water in the passenger footwell. The cause was a blocked scuttle from the windscreen, difficult to find as it had a rubber flap covering the hole. Once cleared out the problem went away though I cleaned it out on a regular basis for the next ten years.


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