W124 Battery and boot lock problem

[dwels]

Hi,

New user looking for a little help with a big problem!

I have a J reg W124 (200TE) with an odd electrical problem that seems to affect several different things. The reason I think it's one problem is that they all started together, went away for a while and all came back together...

When the boot lid is closed, and the ignition is off, power is still fed to various places: auto-aerial, rear windscreen heater, radio. This in itself is just anoying, but it also seems to have a serious drain on the battery - it will go flat if left for 36-48 hours. The battery is brand new.
Opening the boot lid lowers the aerial, turns of the radio, etc. The problem started intermittently - locking and unlocking the boot, opening and closing it a few times and everything would shut off - but now it's constant.

Otherwise, she's a lovely old girl (with 210k) on the clock.

Can anyone help?
Thanks,
Dan.

 

[Bolide]

I only know about estates, but apparently there is a known problem with W124 saloons which results in a dash fire. It's caused by the boot lid wearing through a cable and the (unfused) cable causes a fire at the connector block behind the dash. This is according to Honest John in the Telegraph

Whether this is accurate or not I don't know but I'd disconnect the battery immediately, hook it back up through a 5 amp fuse on a flying lead, and go looking for the problem. If it shorts while you're looking for the problem the fuse will blow. If the battery's disconnected I don't think you'll ever find it

Best thing all round would be to take it to a professional auto electrician - they will likely know the problem

Nick Froome
www.w124.co.uk

 

[dwels]

Thanks Nick. I should have said it is an estate.
Dan.

 

[Bolide]

Ah - you said TE but I read bootlid and thought saloon

The electrical feed to the tailgate goes through a rubber sleeve next to the right hand hinge. Over time the wires crack & break and have to be replaced. I normally cut one wire either side of the tube, pull it through and use it to pull a new wire through. I then rejoin that wire and proceed to the next. If you can, use wires the same colour as the originals to make any further faults more easily findable

The wash/wipe water feed goes through the same tube and it tends to crack too, so replace the section that runs through the sleeve

Whether there's an unfused live feed to the tailgate I don't know, but you've obviously got wiring problems and I'd start at the tailgate. There's a big crescent-shaped connector block up in the o/s headlining in the roof that all these wires go to. With a wiring diagram and a multimeter you should be able to work out of the wiring is good to that block - if it is, the problem lies in the tailgate

Careful when removing the big fibreglass trim on the roof behind the tailgate opening. It's a bit fragile and it's tough to remove. It has clips running fore-aft that have to be unhooked to remove it. With that out you'll see the connector block

This a good opportunity to do the tailgate rams if they're saggy

Nick Froome
www.w124.co.uk

 

[dwels]

That's great. Thanks. I think I'll wait for the weekend for that lot, but I'll let you know how it goes.
And sorry, I'll try and get my terminology right in the future!

 

[dwels]

Many thanks for your info Nick. I actually had 4 broken wires. All are now replaced and everything's working as it should.

 

[Bolide]

Many thanks for your info Nick. I actually had 4 broken wires. All are now replaced and everything's working as it should.

Excellent. If the window winders start getting iffy and only work when the door is half-open you'll know how to fix the problem... it's the same thing

Nick Froome
www.w124.co.uk