W126 sunroof soaking electrics

[oscarham]

Hello everyone,

My W126 has been having some intermittent problems this year - it cuts out randomly. I believe the cause is an aftermarket immobiliser as I have traced wires to the nearside front footwell and found a location it's been spliced in to the vehicle wiring loom - all of these connections are damp and corroded, some snapped off with just a touch. They are definitely not original connections as they are a combination of crimps and scotchlocks!
I think the cause is ultimately the sunroof - the seal isn't great, and it's been on my list of jobs to replace. I predict that it's leaking and the drain channel is blocked, causing water to overflow into the footwell.
I am competent in mechanical and electrical repairs so I'm confident I can fix it, I am mainly looking for points of view from experience. I'm assuming the drain channel runs behind the front wing somewhere so will probably remove that for ease of access.

My question is, has anyone got any experience replacing the sunroof seal, clearing drain channels, or any knowledge of old Scorpion immobiliser systems?
Oscar.

 

[brandwooddixon]

All sunroofs leak, some more than others, but the water drains are the issue. The sunroof "cassette" includes a drainage "panel" that has a drain at each corner. I don't know about your vehicle specifically, you may be able to clear the drains using a long length of net curtain wire, but occasionally the drainage pipe that passes down the A and C pillar may become detached. This can cause corrosion in the pillar seam.

I assume that you've ruled out water ingress through the footwell air vents - this is quite common as the drainage ports under the windscreen scuttle become clogged and then in heavy rain it floods in through the air intake for the interior heating/ventilation system.

In any case that wiring is shocking, looks like a DIY bodge to me.

 

[oscarham]

Chris, thanks for your expertise. There is a bit of rust forming under the battery below the scuttle, so I'll have it out this weekend and see what's going on. I was also planning on removing front wings to check the drainage pipes so I will definitely do that now. I'm not sure if I'd have any drainage pipes in the C pillars as it's a saloon car so the water wouldn't run away, although I will investigate.

The wiring is horrendous, I'm in the process of removing the aftermarket immobiliser so it's all being cut out and replaced with solder.

 

[star]

Discard the scorpion alarm, as above about sunroof, the drain tubes can rust out on cassette. Remove sun visors and trim to see if rusted thru.

 

[oscarham]

@star , thank you that's great advice!