 | Home > In Car Electronics > Tdci heated screen switch |
 
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| 22900013A Member Since: 23 Dec 2010 Location: Oxfordshire Posts: 3150   
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Are they known to fail? Mine has stopped showing the light (it did occasionally still come on but has now stopped completely). I seen to remember they stick in then spring out after a few minutes but I may be wrong. When I press the button there doesn't feel like anything happening, ie no resistance or push back, it just springs back when I release it.
I've ordered a new genuine one as it was pretty cheap, just wondered if anyone had experience/advise? 2011 110 USW 1973 Series III 1-Ton 1972 Series III 1-Ton Cherrypicker 1969 IIA 1-Ton 1966 IIA 88" |
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13th Jan 2024 11:36pm |
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| 22900013A Member Since: 23 Dec 2010 Location: Oxfordshire Posts: 3150
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Sound, so physically as expected but either failed internals or failed bulb? 2011 110 USW
1973 Series III 1-Ton 1972 Series III 1-Ton Cherrypicker 1969 IIA 1-Ton 1966 IIA 88" |
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13th Jan 2024 11:54pm |
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| 22900013A Member Since: 23 Dec 2010 Location: Oxfordshire Posts: 3150
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Just pulled the center dash out, connection looks fine. Tried button and light comes on now. With ignition on but engine off it went straight off again. With engine on it stays on. I'm going to swap the switch when it arrives and hopefully that'll solve it. 2011 110 USW
1973 Series III 1-Ton 1972 Series III 1-Ton Cherrypicker 1969 IIA 1-Ton 1966 IIA 88" |
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14th Jan 2024 10:29am |
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| blackwolf Member Since: 03 Nov 2009 Location: South West England Posts: 17443 
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The heated screen and hence the light in the switch won't come on and stay on unless the engine is running, if it is either a factory fitted screen or has been wired in accordance with factory specs. The circuit uses an "engine running" signal from the IPAC.
Nothing you've described so far sounds like aberrant behaviour. |
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14th Jan 2024 12:55pm |
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| macfrank Member Since: 05 Nov 2015 Location: somewhere in the north Posts: 1081  
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No fancy mechanics. It's just a simple momentary switch that triggers the timer relay for the windscreen, provided the engine is already running, as blackwolf said. The timer then switches a relay which powers both the heater and the LED inside the switch. If the heater is indeed not working, I'd check the fuses to the timer and the relay first. edit: missed you last post :/ Seems nothing is wrong and you now have a spare switch you probably will never need 
To clarify: usually electric systems that draw a lot of power will only turn on with ignition on, i.e. they are wired to the IGN postiton of the ignition switch. Heated seats, for example. The heated windscreen electrics, however, get an additional control signal from the instrument cluster when the engine is running. So IGN is not enough to turn it on. |
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14th Jan 2024 3:36pm |
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| 22900013A Member Since: 23 Dec 2010 Location: Oxfordshire Posts: 3150
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It's done this a few times recently, sometimes doesn't want to work, then miraculously cures itself. I was running the vehicle at night with the heater and lights on when it refused to work, can't remember previous instances specifically but the screen/light did come on eventually. I can only guess something is breaking down, can't imagine a Defender being clever enough to limit voltage use by refusing to activate certain features, it's certainly not been an issue previously. 2011 110 USW
1973 Series III 1-Ton 1972 Series III 1-Ton Cherrypicker 1969 IIA 1-Ton 1966 IIA 88" |
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16th Jan 2024 7:07pm |
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| 22900013A Member Since: 23 Dec 2010 Location: Oxfordshire Posts: 3150
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Just an update on this. Fitted the new switch and still no telltale so presumably wiring? Also the new switch locks in place like the rear heated screen switch, which is rather odd.
Any ideas what the issue is? 2011 110 USW 1973 Series III 1-Ton 1972 Series III 1-Ton Cherrypicker 1969 IIA 1-Ton 1966 IIA 88" |
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25th Jan 2024 8:56pm |
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| custom90 Member Since: 21 Jan 2010 Location: South West, England. Posts: 20441
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My guess is poor connections or contact between switch and plug, possibly a plug connection loose or poor connection to the heated screen contacts.
If there is copper tracks on these screens anywhere perhaps some damage, are they similar to the rear heated screens at all? I’ve only read quickly but if it does it less with the engine running, than with ignition on its worth noting there is a few volts difference between ignition on and alternators charging voltage with the engine running. So if there is a poor connection that can overcome the possible high resistance of a loose connection due to the few volts difference with the engine running. See what current it’s drawing from its fused circuit and see what it is drawing, if it’s below 50% of the fuse rating then there is a sign. I don’t know what the current draw is of this circuit, but if it is say 8.2A, that would look normal if it was rated in the fuse box at a 10A fuse. But if it was only drawing say 1A instead then that tells a lot in its self, especially if the current varies when tested at different times and different scenarios. As you’ve changed the switch, and still the same the LR side socket pin housing maybe suspect, or connections to the heated screen or the screen it’s self. It’s less likely to be wire damage imo but you never know. $W33T $0U7H3RN $UG4R 🇬🇧🏴🏴🏴🇮🇪🇺🇸⛽️🛢️⚙️🧰💪 |
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25th Jan 2024 9:29pm |
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| 22900013A Member Since: 23 Dec 2010 Location: Oxfordshire Posts: 3150
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It did have a new screen fitted late last year, could it be they didn't connect it properly?
I think we can say we have eliminated the switch as the culprit. I assume if for some reason power can't get to the screen the light won't come on? I'll check the fuse tomorrow, if that's intact I'd say it's got to be wiring or a connection somewhere. The fact it's now not working at all suggests a break. That it *sometimes* worked before suggests something coming loose? 2011 110 USW 1973 Series III 1-Ton 1972 Series III 1-Ton Cherrypicker 1969 IIA 1-Ton 1966 IIA 88" |
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25th Jan 2024 10:17pm |
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| blackwolf Member Since: 03 Nov 2009 Location: South West England Posts: 17443
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It sounds as though the replacement switch isn't the right one, it definitely should not latch. The windscreen itself won't affect the lighting up or otherwise of the switch tell-tale, and you will need to obtain (if you don't already have it) the wiring diagram for your model year.
Check all the fuses in the heated screen circuit (there are two involved); check that you are getting power on the "engine running" signal from the IPAC to the time relay. Check that the timer relay is energising the switching relay. It is not unknown for timer relays to fail. The route to solving your problem will involve the circuit diagram and a voltmeter, and careful logical checks. The momentary-contact non-latching switch together with the engine running signal allow the timer relay to be energised(the switch provides the earth path), the relay gets power from a 5A fuse (probably CJB fuse 15 but I am not sure if there are model year variations). The timer relay in turn energises the HFS relay, which is powered from a 30A fuse (probably CJB fuse 36). The output of this relay powers both the HFS and the tell-tale in the switch. If any of the following have failed, the tell-tale will not light up and the HFS will not work: CJB fuse 15, CJB fuse 36, the "engine running" output from the IPAC, the switch, the timer relay, the HFS main relay. About the only thing which won't prevent the tell-tale illuminating is a failure of the screen itself.  Click image to enlarge |
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25th Jan 2024 10:23pm |
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| custom90 Member Since: 21 Jan 2010 Location: South West, England. Posts: 20441
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I’d be most suspicious of grounding point: C0809-01 in the bottom right corner of the diagram Blackwolf provided, is there more details on where that is located?
K108 is also a possibility. Checking the voltage at fuse 15 & 36, and the above two grounding points could help locate the fault. And if the two fuses are in-tact, then I’d then look at replacing Relay R208 there is D247 as well, presumably the latter costs more? If they aren’t overly expensive it might pay just to replace both to save the fault fining exercise if they happen to be cheap enough and it may be one of those especially the timer delay one as Blackwolf mentioned. Earth faults are common tough. Sometimes switches stick, because they touch the side of the dash and get stuck on it when they shouldn’t. An elastic band can stop that loped around another at the rear, I had this once with one of the switches on the upper left top of the centre dash and an elastic band around the rear just kept them uniform enough to stop the one switch sticking on the dash side. It’s hard to explain, but that’s the reason why they do it sometimes. If the switch is out of the dash and pops back once unlatched then it should do that in situ. And if it’s a non latching switch then it should always pop back in the same way unless pressed and if it doesn’t then it’s catching on another switch fascia or dash surround. As Blackwolf mentioned methodical checking is needed, live voltage checks for the live side and continuity for the ground to start with. Using a good separate ground to do the voltage checks as well, I’d check the grounding points or add a quick temporary one first. If it isn’t ground points, and the R208 relay seems okay, then I’d look at replacing D247 as Blackwolf mentioned. Bearing in mind if the fuses are okay, and the relays seem to be working or partially it could well be the ground as that will have random effects and effectively will turn it off and have many strange effects. Checks for water as well, especially a wet relay. I’d imagine the timer relay failure or grounding would be places to look, the tell tale light going off obviously means a break in the circuit within that circuit on live or the ground side. Ground faults are one of the most common, and can give the impression of relay failure as fuses seem in-tact and without sufficient grounding relays do not then work. I don’t have a heated screen on mine, and Blackwolf knows his stuff with this one and as mentioned the diagram he has found for you will be key with methodical checks of it. A multimeter is ideal.  $W33T $0U7H3RN $UG4R
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26th Jan 2024 12:12am |
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| Linds Hanson Member Since: 16 Jan 2021 Location: Cornwall Posts: 486
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There's a issue with these switches at the moment coming through wrong I've reported it to JLR parts but got the usual oblivious response and apparently no old Defenders there to try the momentry switch operation! They are just sending out click on click off YUG000470LNF HRW type switches in the correct YUG000460LNF bag. |
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26th Jan 2024 11:47am |
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| 22900013A Member Since: 23 Dec 2010 Location: Oxfordshire Posts: 3150
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That explains why the new one is wrong - and here I was thinking genuine would be correct!
 2011 110 USW
1973 Series III 1-Ton 1972 Series III 1-Ton Cherrypicker 1969 IIA 1-Ton 1966 IIA 88" |
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26th Jan 2024 12:44pm |
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| macfrank Member Since: 05 Nov 2015 Location: somewhere in the north Posts: 1081
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Strange it did fit as connectors and dash are keyed.
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26th Jan 2024 1:57pm |
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