jekyllman
Member Since: 27 Dec 2020
Location: Pocatello
Posts: 42
  
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| Heated windshield/windscreen - perlexed |
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Alright so the left side works great. Left side doesn't (hasn't since I've owned it). I popped the A pillar covers off to see if I could identify any issues and test the connections. Everything checked out on both sides and now I don't know what to think. Here's what I've done:
1. Fuses are both fine
2. Relay MUST be good if one side is working
3. Both sides test great on continuity
4. While running and the heated windshield button pushed, both sides (at input connectors) test at around 14.5V
5. While running and the heated windshield button pushed, both sides max out my 10A multimeter which is telling me I've got a current
6. I've tried cleaning the connectors and verifying there's a tight fit
7. The wires on the left are purple on top and black on bottom. It's the opposite on the right side. I thought this could be an issue but the wires are only long enough to reach the windshield connector that it was connected to. Because of that I figured it was as designed and it also doesn't really allow me to test without connecting a jumper lead to one (which I can do if you all think this could be the source of my problem)
Any other ideas? I'm totally at the end of my understanding on how these work.
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 22nd Jan 2022 11:07 pm |
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Globetrotter448
Member Since: 21 Mar 2017
Location: Londonderry NSW
Posts: 1797
  
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Find which colour is the power side and connect power to it and see if it works. If not then broken wire in the windshield.
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| 22nd Jan 2022 11:18 pm |
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Pete K
Member Since: 15 Jan 2016
Location: GL
Posts: 10492
 
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The only thing you haven’t done is disconnect the windscreen and measure it’s resistance.
Should be around 1R
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| 22nd Jan 2022 11:37 pm |
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jekyllman
Member Since: 27 Dec 2020
Location: Pocatello
Posts: 42
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That was one of the first things I did. Both sides measured the same
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| 22nd Jan 2022 11:44 pm |
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jekyllman
Member Since: 27 Dec 2020
Location: Pocatello
Posts: 42
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Globetrotter448 wrote:Find which colour is the power side and connect power to it and see if it works. If not then broken wire in the windshield.
According to the wiring diagram the purple wire coming in is the power and black is ground. Both leads on the windshield are identical. Should it matter if the leads are swapped anyways?
https://disco3.co.uk/gallery/albums/userpi...age_60.pdf
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| 22nd Jan 2022 11:46 pm |
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Admirable
Member Since: 19 Jul 2015
Location: Fife
Posts: 1032
 
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Have you tested the black wire (ground/earth) of the side that is not working has a good connection to Ground?
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| 23rd Jan 2022 12:00 am |
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jekyllman
Member Since: 27 Dec 2020
Location: Pocatello
Posts: 42
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What I did was place my multimeter leads into the two female connectors (vehicle side) to test voltage and amperage. My assumption being that the ground was adequate as the measurements were successful
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| 23rd Jan 2022 12:07 am |
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galwaygreen
Member Since: 30 Oct 2011
Location: plymouth
Posts: 6525
  
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I now know where POCATELLO is
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| 23rd Jan 2022 1:42 am |
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Yankee_Rover
Member Since: 02 Jun 2021
Location: Seattle
Posts: 183
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Agree that you need to check ground, seeing as you have power to the windshield
and the resistance of both halves matches. Im not sure your current reading is tells the full story since the windshield can pull 27.5a but your DMM maxes at 10a. A poor ground could be limiting your current such that the windshield gets slightly warm, but not full temp. 2008 LR3 HSE, 4.4L V8
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| 23rd Jan 2022 4:11 am |
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jekyllman
Member Since: 27 Dec 2020
Location: Pocatello
Posts: 42
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galwaygreen wrote:I now know where POCATELLO is
Hidden gem!
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| 23rd Jan 2022 7:07 am |
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jekyllman
Member Since: 27 Dec 2020
Location: Pocatello
Posts: 42
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Yankee_Rover wrote:Agree that you need to check ground, seeing as you have power to the windshield
and the resistance of both halves matches. Im not sure your current reading is tells the full story since the windshield can pull 27.5a but your DMM maxes at 10a. A poor ground could be limiting your current such that the windshield gets slightly warm, but not full temp.
So I went back out and checked the ground lead everything looked good.
One additional piece of intel: I had the vehicle running and both sides unplugged with the heated windshield button active. I plug in the leads on the bad side and nothing happens. When I plugged in the good side it arced slightly and you could hear the engine/alternator lag a little under the load. To me this is showing that there really isn't a load on the bad side but no idea why... I tried to jiggle the leads and wires on the bad side to see if it would be an intermittent connection issue but got nothing from it.
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| 23rd Jan 2022 7:11 am |
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Admirable
Member Since: 19 Jul 2015
Location: Fife
Posts: 1032
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I'm still not convinced you have a good earth on the faulty side.
Can you connect a wire from earth connector from the faulty side of the screen to a known good earthing point on the car, the negative side on the battery would be ideal.
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| 23rd Jan 2022 8:31 am |
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Pete K
Member Since: 15 Jan 2016
Location: GL
Posts: 10492
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Yeah check ground
I think you measured current wrong
You need to break circuit and allow current to flow thru meter to measure it. (Series)
I wouldn’t do this as you will damage your meter. Well you could risk it on broken side I guess.
I think your current readings maybe invalid as we would expect with screen not actually working.
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| 23rd Jan 2022 10:19 am |
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jekyllman
Member Since: 27 Dec 2020
Location: Pocatello
Posts: 42
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This is what I did (I believe). I unplugged the windshield and plugged the meter into the connectors and turned on the windshield. Pulled the leads as soon as it shot up as to not blow the fuse.
I’ll check on the ground again. I need to find where it’s actually grounded to the body and see how that looks too.
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| 23rd Jan 2022 9:15 pm |
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Yankee_Rover
Member Since: 02 Jun 2021
Location: Seattle
Posts: 183
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Argh, had a long post but then browser froze.
In summary, you don’t need to find your windshield ground strap yet. Find a working ground point on your car with your test lead and then check for continuity from the ground pin in the windshield connector. If no continuity then you can trace your wiring for inspection. Make sure your test lead ground is good before making any assumptions about your car’s wiring.
Don’t worry about the current testing yet as your problem still sounds like a bad ground. If you do try testing current beware you could blow your DMM since this circuit is 30a and most consumer DMM max out at 10a. If needed, we can come back to that later.
Lastly, be careful with inserting DMM test leads into connectors as they will spread the pins and give you bad connections later. Use fine test lead probes or some stranded wire in the connectors, just dont force anything.
Good luck!  2008 LR3 HSE, 4.4L V8
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| 23rd Jan 2022 10:32 pm |
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