2003 R170 SLK320 Seat adjustment relay

[MercSLK]

Can any of you good folks tell me where the seat position adjustment relay is located in a (UK RHD) 2003 R170 SLK320. Intermittently, neither seat is able to be adjusted and then it all starts working again normally. It looks like a dodgy relay but I don't know where it is located nor how to get at it. Can anyone help?

Thanks

TimR

 

[MercSLK]

Hi Alexander

The first part of the VIN is:

WDB1704652F30xxxx

Thanks

TimR

 

[MercSLK]

Bump

 

[mattkh]

I dont have a SLK.
Does the owner's manual throw any light on the subject..?
By the way, are you good at taking snaps and linking them to the forum..?

 

[MercSLK]

The relay is normally a dealer replacement part and isn't a normal service part and isn't/won't be mentioned in the owner's manual. Yes, I can take snaps and have no problem attaching them to forum posts.

 

[alexanderfoti]

Hello

You are looking for the K24 relay, upper drivers footwell, near top of brake pedal lever

This may be of help

Intermittent seat adjustment problem. Seat relay fix.

Hi folks! It's been a while since I've been to DIY section. I thought we should have a dedicated thread to the following issue: Intermittent seat adjustment problem. I have replied to the thread on Benzworld...

www.slkworld.com

 

[MercSLK]

Thank you both Alexander at AMF Automotive and Cole at MBS. Defective relay accessed and removed. Cover opened and a number of failed/suspect solder joints on the PCB identified. PCB reworked, relay re-assembled and re-fitted. Electric seat adjustment now restored to normal operation. Thanks a lot to both of you. Very happy camper!!

TimR

 

[mattkh]

Thank you both Alexander at AMF Automotive and Cole at MBS. Defective relay accessed and removed. Cover opened and a number of failed/suspect solder joints on the PCB identified. PCB reworked, relay re-assembled and re-fitted. Electric seat adjustment now restored to normal operation. Thanks a lot to both of you. Very happy camper!!

TimR

Well done.
I wish I had requested a photo of the suspect solder joints.

 

[MercSLK]

Well done.
I wish I had requested a photo of the suspect solder joints.

To be honest, there wasn't much to see. Almost certainly wouldn't have shown up on a normal camera. I'm a retired electronics tech. and I've been doing through-hole component level PCB repairs and PCB re-work most of my working life. It kind of becomes second nature eventually. If you need to repair your own unit. remove the cover and re-work the heavy connections to the actual relay inside. Don't just re-flow the connections. Remove the solder and clean the relay connections with a fibre glass pencil and then re-solder using some liquid or paste flux and 'proper' 60/40 leaded solder. Do the same with the relay unit pins where they connect to the PCB. That should fix it OK. The surface mount stuff is generally OK and doesn't need to be touched.

HTH

TimR

 

[mattkh]

Most grateful to you.
Can these defects be put down to vibration..?

 

[MercSLK]

Most grateful to you.
Can these defects be put down to vibration..?

Combination of things...the relay has mass and is secured to the PCB only by the soldered joints. In industrial equipment a component with mass is usually secured to the PCB using threaded fasteners and solder is used simply to make the electrical connections. The current to operate the seats is reasonably high and will stress the soldered joints due to heat especially as they begin to fail. The type of solder used in this assembly is lead free which has inferior wetting properties to leaded solder. And yes, vibration will cause the solder to crystallise, the resistance will rise causing heat which will result in oxidation and ultimately failure of the joint. Hence the requirement to remove all the existing solder from the failed joint/s, to clean the contact areas using a fibre glass pen and then re-new the solder with leaded solder with its superior wetting qualities.

HTH

TimR