Dash light for rear screen defogger comes on when switched but rear screen is not clearing at all when misted.Swapped a working relay from another mk1 clio and checked connection tabs but no luck.Also tailgate central locking not working when using the remote even after replacing lock motor.Will be gratefull for any advise.Thanks
Im not too sure about electrics in a MK1 Clio but I will try help if I can. I hope you have a multimeter handy? If not your gonna need one. First thing to check is if the rear window is getting a supply from the battery(I think im right in saying there is 2 copper strips either side of the window?) Put your multimeter(on 20v DC) on these and switch the rear defogger on, it doesn't matter what way round you put the leads, if it reads a voltage it will either be a +v or if you get it the wrong way a -v. If you get a voltage then the problem lies with the window I presume.
If you don't get a voltage you want to check the window has an earth and also a supply.
To check the earth connect a multimeter(on low resistance setting) to the earth from the defogger to a clean area of metal that is attached to the body, i.e a door hinge or something. Make sure you get a low resistance if not try another spot and if that fails then you have a bad earth.
If that is ok, then the next thing to check is that you are getting power to the rear window. The method I would use works on ships and should work on cars since the bodywork is an earth in both cases. First of all disconnect the battery to avoid short circuits. Some crocodile clips or similar would be very hand here, connect the crocodile clips from the supply side of the window to either the earth at the other side or the body work. Now all you need to do to check that the window is gettin power. If you go to your fuse panel and remove the fuse for the rear defogger, insert one of the leads from your multimeter into where you just removed the fuse(note that there is 2 slots) and connect the other lead to the body work somewhere. If you get a high resistance then try putting the lead from the fuse holder into the other slot and check what reading you get.(one side is feed and the other is supply). If you get a low reading then the cable to your rear window is fine and the problem lies with the window or relays etc. Also have a good look and make sure there is no loose connections.
I hope I haven't over complicated this too much, its hard to keep simple.