04 SL350 Owner

[GJC]

Hello all, my wife owns the Merc, but I (try) and look after it!
She’s had it since 2010, in that time it’s been pretty good.
Recently the central locking has been playing up, I’ve read all the threads about the PSE pump & wet boot etc...... pump & boot are dry! Central locking works when it wants, it’s been on the drive a couple of days as it’s low on fuel and currently the car doesn’t want to be unlocked! I took the fuse out (behind drivers seat), it wasn’t blown, when I put it back in, everything unlocked. Rushed to petrol station and filled up. Accidentally locked the car, had to manually open it. Got home, pulled fuse and put it back in, car unlocked again. Car would lock unlock fine on the drive, at some point when driving (bumps?) the system stops working until fuse is pulled and put back in!

 

[Blobcat]

Hello and welcome

 

[sonic]

Welcome lots of SL owners on here but I am not one, but I am sure they will be along shortly.

 

[Srdl]

Hello and welcome

 

[SL63 Mark]

The fact the PSE pump works when you pull the 20A fuse behind the drivers seat and then fails again means it is timing out possibly because of a vacuum leak. Mine used to do this when the boot lock failed. Pull the fuse and it will reset the pump which works for a bit, and then it fails again.

So your pump may be OK (which is good news) but there is a vacuum leak somewhere. It is possible to check for this, if you are handy at pulling vacuum lines. OR it may still be the pump. Best thing is get it to an Independent Mercedes Specialist with star. Unfortunately my money is on the pump, these only have a limited service life, and yours has done well to reach 16 years if it is still the original. A new/recon one is about £600 fitted if I recall correctly, mine was a bit more than that as I had MB fit it.

 

[dry run]

Welcome

 

[LostKiwi]

Hi and welcome.
As mentioned sounds like a vacuum leak. One of the usual suspects is the soft close on the bootlid or the vacuum bellows on the boot lock (they are separate items in the same assembly)
Easiest way to test is a vacuum tester on each of the lines from the pump.

 

[GJC]

Thanks for all the replies folks, I’ll let you know how I get on

 

[LostKiwi]

Sometimes you can hear a hissing from the leak if you listen carefully.

 

[GJC]

Didn’t get chance to investigate this weekend, hoping to have a look later today

 

[00slk]

Hello and welcome

 

[GJC]

Thought I’d have a bit of an investigation today, pulled fuse and put it back in, nothing
Is it possible to connect the pump direct to the boot battery just to check if it runs?

 

[A.J.]

Hi and welcome to the forum

 

[GJC]

Ok, pulled the fuse and left it 10 mins & plugged it back in, everything unlocked so I pulled it again as we are low on fuel

 

[SL63 Mark]

Sounds like your pump is running, but timing out. It will run for a few seconds, but it it senses a leak, it will cut out to stop it running indefinitely and burning out. The pump can be reset if you pull the fuse, wait for a few minutes and put the fuse back.

As mentioned in posts #5 and #7 above, the most likely scenario is a vacuum leak.

Can you hear hissing anywhere ?