Electrical & Lights Rear heated screen electrical fault?

Discussion in '7th Generation (2003-2008) [Acura TSX]' started by steveb216, Monday 1st Aug, 2016.

  1. steveb216 Junior Member ☆ ☆ ☆ ☆ ☆

    Hi, I'm looking for some advice for an issue that has developed with my 2004 Honda Accord 2.2 I-CDTI.
    My rear screen was recently broken after being hit by a golf ball t the top left corner. I called my insurance and got it replaced. The replacement screen then literally 'exploded' about 6 hours after being fitted. The glass company visited again several days later and said that there's an electrical fault with the heated screen which caused the failure so have left it disconnected after replacing the glass.
    When the ignition is on but engine not running, there is 12v supply at the screen even though the heated screen switch is off.
    With the engine running and the screen switched on, the supply voltage is approx 14v at the positive supply to the heated screen element.
    When I switch off the heated screen switch and engine, there remains +14v at the positive side of the screen. The voltage slowly drops but still remains at 12v which suggests the screen would remain 'live' if it was connected.
    I have tried replacing the amplified antenna module on the C pillar (which also has the heater connections) but this has not resolved the problem.
    I cannot see any problems with the relay or fuse as power is getting to the screen. I never experienced any previous issues with the heated screen or battery being flattened before the screen got broken.
    I've searched many other threads but issues discussed are about the screen failing to turn on rather than not switching off.
    Has anyone else experienced anything similar with their Accord? Is there another fuse/relay/connection/control unit that I can check out before resorting to calling an auto-electrician? Any help would be gratefully received. Thanks.
     
  2. Zebster Expert Advisor ★ ★ ★ ★ ★

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    Any electrical fault with the HRW that could have led to its destruction must have been in the actual heater matrix of the rear windscreen... The vehicle is practically unable to supply excessive current to it.

    I agree the voltage readings are odd, but you are measuring voltage on an unloaded circuit. In any case, applying anything up to about 15v to the HRW is normal and any of us could leave our HRW on for extended periods.

    I think you were given a faulty rear windscreen.
     
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    legend-ary likes this.
  3. Nels Moderator Staff Team

    Ditto.
     
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  4. Zebster Expert Advisor ★ ★ ★ ★ ★

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    I'd reconnect the HRW and try it. Assuming there wasn't a batch fault during the production of your rear windscreen then I'd expect it to work perfectly normally.

    I'm not sure I'd believe a glass company's diagnosis that there's an electrical fault... Especially when they could well be covering up a problem with the product they're installing!
     
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  5. legend-ary Moderator Staff Team

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    Agree with @Zebster . Can't even remember how many times have us lot left the rear screen heater for miles and hours with no adverse effect.
     
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  6. steveb216 Junior Member ☆ ☆ ☆ ☆ ☆

    Hi all,
    Thnks for the replies/advice.
    My first thought was that it must have been a faulty screen/fitting but had no way of being able to prove it. Having spent more than a week with no rear screen I just had to suffer a second excess charge on fitting a replacement. The glass comany did say they were sourcing a different brand of replacement screen for the second one. Not sure what that says?
    I'll connect up the HRW and measure the voltage with and without the engine running. I hope that with a load across the circuit that the voltage will drop off quickly after switch off.
    Fingers crossed! Thanks.
     
  7. Zebster Expert Advisor ★ ★ ★ ★ ★

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    But if you had an electrical fault that caused the HRW to be constantly on (or partially on) then this condition would have been present on your original rear windscreen! And then you'd have had a flat battery in the mornings...
     
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  8. steveb216 Junior Member ☆ ☆ ☆ ☆ ☆

    Thanks Zebster - that's exactly what I was thinking.