Electrical Gremlins progress - W124 E250 TD Estate

mjhmjh2

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Some progress with the 1986 E250 TD this evening I'm happy to report.

Interior light staying on and seat belt light always flashing. I found a wire for the disconnected alarm on one of the switches, it tapped out as earth even though alarm end was disconnected - I suspect it had worn away the insulation somewhere - that removed and the lights now go off and on with the front doors.. Took about an hour to figure all that out

Interestingly my front doors have two switches on each side - the top switch control the front interior light and seat belt warning lamp, the bottom ones I've no idea what they do - Does anyone know what these are for? Also the rear doors have switches these don't appear to do anything either these appear to have no voltage at them though.

Rear passenger lights and boot lights - all bulbs had positive both sides, but no positive at rear door switches so I'm not sure if those are activated by the doors or not. I remember seeing a switch on the dash that looked like an interior light symbol so I pulled the centre console covers out and checked the switch (no circuit in either position between any of the 4 pins), I also noticed that the 4 wires to the switch had been cut! I worked out which ones were which and a quick tap test and the lights all worked, so I soldered all the wires back together and used a spare switch and now the lights switch on and off (even though the replacement switch is a 3 position one)

So now I have interior lights (or rather lack of them when the doors are closed) which is rather nice :) If anyone knows what the rear door switches are meant to activate and the front second door switches (all look factory fitted) then please let me know.

Next job try and figure out what is wrong with the two electric windows, weld the o/s wheel arch where washer bottle was leaking and replace washer bottle / pumps.

Matthew
 

television

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I cant offer anything, but thanks for posting up your progress, hopefully some can give you some answers to your questions
 

Bolide

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The fault's in the interior light assembly. Replace that and everything should be OK

If you look at the circuit diagram, the only thing that can keep the seat belt light flashing is the circuitry in the light assembly

Nick Froome
www.w124.co.uk
 
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mjhmjh2

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sorry I think i didnt explain myself properlly...

The interior light now works just fine with the front doors - it goes on when you open a door and goes out about 10 seconds later (unless the ignition is on and it goes off straight away when you close the door)

The rear lights work with the dash switch... but I dont know what the second set of pins in the front doors and the set of pins in the rear doors are meant to do - I've not managed to find any obvious colour match on the wiring diags in the haines book yet. (Oh there is no boot switch which is interesting as haines would suggest I do have one!)

It's not really that important but the curiousity factor is starting to get the better of me!

Matthew
 

MotardMan

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but I dont know what the second set of pins in the front doors <snip> are meant to do -
It's not really that important but the curiousity factor is starting to get the better of me!

Matthew

I think they are for the factory fitted alarm system. My 94 E320C has them too, I was a little confused about it, but assumed that one set of switches was for the interior lights, and the other sense when a door is open for the alarm?

Am I wrong? Anyone? Help us out, please?

Jim
 
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mjhmjh2

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thats what I was guessing too - however I've no factory fit alarm, only a dodgy laser aftermarket one... which is slowly being removed!

Matthew
 
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mjhmjh2

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I searched all the edges of both the boot lid and the boot lip and there is no swtich on mine.. there is no hole or place where one could have been either.. I might put one in though as it would be easier that using the dash switch.. All 4 lights are wired in parrallel so I only need to earth one of them.

Matthew
 

Myros

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the boot light switch

is a microswitch on the lock mechanism itself. It senses the opening closing of the lock and puts the lights on or off accordingly. Mine has just fixed itself after nearly a year of me thinking it was busted.
You can only see it by taking off the lower tailgate trim and wibbling the locking mech out.
 

Bolide

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The front windows on a W124 work with the ignition off only when a front door is open. So the second set of switches probably feeds the windows. 5 minutes with a meter will confirm this one way or the other

Nick Froome
www.w124.co.uk
 

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