Laguna Heated rear screen

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Joined: 05 Jan 2004, 20:10

Laguna Heated rear screen

Post by kwilby » 05 Jan 2004, 20:20

The heated rear screen has suddenly stopped working in my L-reg Laguna hatch. The relay is OK and both side mirrors get warm when the button is pressed. I've metered the element and it reads (on my cheapo meter) zero ohms. If I disconnect the +ve connector and press the button I get a reading of 12V, but as soon as I re-connect it it reads 0V.
My questions are, is 0 ohms normal and assuming it is, what is the likely cause of the voltage dropping to 0 when the element is connected, bearing in mind the side mirrors get warm?
Many thanks.

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Post by badluckwithcars » 06 Jan 2004, 19:04

check the earth points for the screen, i had the same prob with my clio. I just rerouted the earth to the wiper motor and it has been fine eversince.

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Post by JimW » 07 Jan 2004, 04:58

You need to re-run your tests after finding a good earth point nearby. Note - this may not be that easy !
Now - with the switch on - check the voltage from the good earth to both sides of the heater element. If both show (roughly) 12V then your problem is a bad earth.
Alternatively (with eveything off and the element disconnected), check the resistance from the good earth to the earth for the element.
I've just fixed faulty heated rear screens on my Laguna estate.
My problem turned out to be in a big connector block, which is located behind the trim panel, just in front of the front passenger door and a couple of inches off the floor.
The pin & socket for the 12V feed to the heated screens had, for some reason, started to get hot - this tends to cause all sorts of problems, basically making things worse and worse and the resistance here increases until it's virtually open circuit.
It isn't too difficult to gain access to this connector block - if you can, then a simple test (again with the element connected and switched on) is to just look at the voltage either side of this block (look for the fattest white cable).
There should be no real voltage drop across the connector (say less than 0.1 V), however, if your problem is here, then you'll see pretty much a 12V drop.
Let us know how you get on...

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Post by Nige » 05 Feb 2004, 23:44

Hi, if its a hatchback like mine, there is another white connector block behind the trim by the bootlight, mine had melted around the fat white/green wire (HRW + feed), snipped wire either side of connector & made good connection with yellow (the big ones)bullet fine now.
Looking around the net I found info on the connector that gave me trouble, the one that JimW states & apparently thee are a couple of connectors at the base of the dash fusebox (above your right shin) that can cause the same problem.
Would you believe, some pondlife is actually selling the above info on ebay for £5.
Hope that is of some use

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Post by TazzyK » 23 Feb 2004, 19:54

i agree with Nige! i had the same problem with min, but it wasn't the earth from the connection box that was faulty, it was actually the live feed. i just re-routed these and connected both ends together bypassing the connection plug....been ok ever since!

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Post by reblack68 » 24 Feb 2004, 01:06

The HRW in my M reg Savanna didn't work when I got it, along with the tailgate speakers. It turned out that the wires inside the rubber trunk between the tailgate and body were broken. I soldered a long-ish piece of wire onto the broken ends and stuffed the joints (securely insulated of course) into the body and tailgate so only new wire was flexing.