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DOH! I must've messed up interior light wiring

I had replied before reading page two of this , but agree with my namesake !
 
Pontoneer
Thank you for your advice, but hopefully, dissing the brown/grey will work.
For some reason, I have the confidence that it will.
If it works, then I have an embarrassing confession to make.
Druk
I will be able to sleep tonight that little bit deeper because I am now quite optimistic that it is going to work.
 
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Druk
Dissing the brown/grey cable did not make any difference to the lights.
They stay on all the time.

So, here is what happens when I disconnect that cable.
I sit in the boot and use the remote central locking to lock the car while watching the lock mechanism and listening.
1- I press the lock button of remote,
2- All locks lock, including that of tailgate!
3- However, there is a strange continuous whirring sound coming from the tailgate lock and lasts for 10-15 seconds. As if the tailgate lock is trying to perform/execute something but can’t.
I stand behind the car and shut the tailgate. The normal "soft shut" that you see in any w124 estate tailgate with the sequence of pleasant noises do not happen. It is this different horrible whirring that happens. The tailgate shuts and opens manually alright though.

Now, I reconnect the brown/grey cable.
All starts working perfectly except for the interior lights which still stay on.

I have a spare w124 estate. I opened the tailgate, explored the connections and can confirm that there is definitely no difference from those of my car.

In my car, I even cut the 2 layered hosepipe protective cover for the bunch of cables that lay next to the left gas strut. I examined these cables very carefully. There does not seem to be any sign of damage.

So, here we go again.
The rear interior lights stay on regardless. I am unable to turn them off.
Currently, my only option is to remove their bulbs or electric connections.

Any suggestions?
 
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You've checked the switch at the dash is in the off position?
Check the operation of both rear side door switches and that one of the wires on the back is brown/grey. The other should be brown. (just to confirm my older model wiring diagram is correct)

Somewhere or other that brown/grey wire is going to ground to cause the lights to be on.
 
You've checked the switch at the dash is in the off position?
Yep.
It is in the middle.
I double checked the right position by comparing with the dash cotrol on my spare w124 (in which the rear interior lights are working fine).
Check the operation of both rear side door switches.
They have no effect on anything. The lights stay on.
Which reminds me. I replaced both rear doors. But, didn't touch those switches.
one of the wires on the back is brown/grey. The other should be brown. (just to confirm my older model wiring diagram is correct)
These are exactly the right colours.
P1030511-Copy.jpg

Somewhere or other that brown/grey wire is going to ground to cause the lights to be on.
Could it be one of the switches of rear doors that I replaced?
Would you recommend that I replace or check these switches? I have a spare car to cannibalise from you see.
 
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not sure if this helps but mine has the same issue with the rear lights in the C and D pillars stayiing on if the tail gate isnt shut properly. My locking motor does not work but still locks when i slam it if i dont slam it hard the rear lights stay on again not effected by the dash switch. there is a micro switch in the rear lock mech which may be the problem? anyway good luck hope you sort it soon.
 
Just a thought, in view of the fact that you have been working on the rear doors, are the strike plates present at the door locks?

Dec

D_2.jpg
 
Check the bulbs and connectors in the very rear. I had the same problem on my car (rear lights on all the time) and it was a bad connection to one of the rear lights.
 
Would you recommend that I replace or check these switches? I have a spare car to cannibalise from you see.

Some good suggestions above. The switches are easy checked by simply shorting them out with a screwdriver across both terminals.
 
there is a micro switch in the rear lock mech which may be the problem? anyway good luck hope you sort it soon.
Any chance someone has a diagram, sketch or a picture of that microswitch?
 
Rear interior lights are still on all the time.
I have disconnected their leads to avoid draining battery.
Thanks to all who previously replied with their suggestions.
I will keep an eye on this thread. If someone comes up with the solution, or has any other suggestion, please add your reply to this thread.
 
I have found a diagram for W124 interior lighting.
Anyone could now tell if there would be any reason why my rear lights are always on?
Shall I replace the light switch?
Thanks
W124InteriorLightingElectrics7.jpg
 
Looks like the rear light should come on
If a rear door is open
OR
If a front door is open (this should also bring on the front light)
OR
Light switch is turned on.

If I were testing, I would remove the grey/blue wire from the switch.
Light stays on, it is NOT the front door switches.
Light off, it is the front door switches, or a short in that circuit.

Then disconnect switch completetely
Light stays on, it is a rear door switch or a short in that circuit. This includes the possibility that the brown/grey wire has a short to earth.
Light goes off, it is the switch.

I think that covers it.
 
Thanks Ted for the advice.
Will try these steps soon.
I need to find out how to access and remove the rear switch from the dashboard first.
It is the switch shown in the 3rd picture in post #1 of this thread.
Probably instructions are somewhere on this Forum.
I suppose I will have to remove the facia?
 
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RESULT
It was the switch in the centre console.
I scavenged a switch from my spare W124 and everything works perfectly.
Thanks to everyone who helped.
 

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