TRbeginner Posted July 12, 2017 Report Share Posted July 12, 2017 Hi all A recent simple 'under dash' re-wiring job has sort of mushroomed to include problems with the blower switch. I removed and replaced the switch/control panel (ignition, blower etc) for other reasons and when reinstalled the fuse supplying the 'green circuit' kept blowing. I think this has been caused by part of the blower switch terminals earthing on the surrounding metalwork of the actual panel/dash. When I removed the blower switch to investigate, there appear to be two spare connectors on the switch (given that only three wires are connected to the switch - G, GN, GY). What is the purpose of the other two, apparently spare, terminals (see pics please)? Is there a recommended way to stop the switch shorting on the surrounding metalwork? Also I noted that two of the switch wires (GY, GN) rise, through a grommeted hole, into the heater box, presumably to the blower. However, there is a third wire (W) which is separate to the blower switch wiring which also goes into the blower mechanism - what is the purpose of this (shown in pics) please? The lower end is (very amateurishly) connected to a female bullet connector, with nothing on the other side! Just wondering whether to remove the complete dash assembly to sort some of this wiring once and for all - but the better weather is beckoning. It feels like a big job - is it? Thanks David Quote Link to post Share on other sites
AndrewMAshton Posted July 13, 2017 Report Share Posted July 13, 2017 Hello David, it looks like you have caught the bug, tinkering, and one job always lead to another, bigger job! Have you a wiring diagram, essential and if you can get it blown up to A3 even better. The green wire is live when the ignition is switched on, the GN/GY are the supplies to the slow/fast windings on the fan motor, there will be a black earth somewhere. White is normally reserved for the ignition curcuit so I think (and I have a 4A not a 5) it is an addition, if one end is bare what I would do is either tape it up or trace back to source and remove. If the switch casing is live then I think you have a faulty switch or the boot on one of your terminals is damaged. For reasons I won't go into here I have rewired my car 5 times and will be redoing it this winter, I picked up some good ideas along the way and happy to share if you decide to delve deeper, cheers, Andrew Quote Link to post Share on other sites
TRbeginner Posted July 13, 2017 Author Report Share Posted July 13, 2017 Hi Andrew, thanks for your thoughts. Seems like Ive caught some sort of bug - unplanned and self inflicted I think. Curiosity got the better of me when I changed the lighting stalk a while ago! Yes I've got a wiring diagram and the blower wiring looks correct apart from the white wire disappearing up into the blower, which I also feel may be surplus, but it is an unusual addition I feel. I guess there is a black earth within the blower/heater assembly but I've shied away from further dismantling currently. As far as the blower switch is concerned, when 12v is applied, the switch body isn't live (0 volts), however on both blower speed settings the two 'spare' terminals on the switch are live (12v). I'm scratching my head 1) why are these spade terminals needed? 2) why arent they protected/insulated - it seems madness to have live terminals so close to other metalwork? 3) am I right to make an assumption that when the switch is in situ it is one of these terminals that is shorting out against the under dash metalwork? The blower worked fine until I removed this panel a while ago and then started shorting on re-assembly. An added problem is that when I put 12v through the blower switch (at either speed) the blower doesnt work. I dont know whether it worked previously. Best David Quote Link to post Share on other sites
RogerH Posted July 13, 2017 Report Share Posted July 13, 2017 Hi David, have you got this series of circuit diagrams http://www.advanceautowire.com/tr2506.pdf As pointed out by Andrew the White is shown as Green in the diagram - it supplies the 12V On the earlier cars 4/4A it is a White wire and again simply supplies the 12V.. If you take the dash off don;t forget to check the big-ends, and the clutch fork pin, and fit an electric rad fan............................................ It will be never ending. Put it all back together and run the car for the summer. The winter will give you time to sort it out Welcome to the forum Roger Quote Link to post Share on other sites
bob-menhennett Posted July 13, 2017 Report Share Posted July 13, 2017 David Useful diagram from Holden Vintage & Classic https://www.holden.co.uk/productImagesWD/34477.jpg You could slip some transparent insulation sleeves on the " spare " terminals but do check out the possibility of something else shorting it out. Bob Quote Link to post Share on other sites
peejay4A Posted July 13, 2017 Report Share Posted July 13, 2017 The reason there are unused terminals is because the switch will be used in a number of different applications such as lighting or wipers. Quote Link to post Share on other sites
Guest ntc Posted July 13, 2017 Report Share Posted July 13, 2017 Common problem just rotate it so the pins are on the side. Quote Link to post Share on other sites
TRbeginner Posted July 13, 2017 Author Report Share Posted July 13, 2017 Hi David, have you got this series of circuit diagrams http://www.advanceautowire.com/tr2506.pdf As pointed out by Andrew the White is shown as Green in the diagram - it supplies the 12V On the earlier cars 4/4A it is a White wire and again simply supplies the 12V.. If you take the dash off don;t forget to check the big-ends, and the clutch fork pin, and fit an electric rad fan............................................ It will be never ending. Put it all back together and run the car for the summer. The winter will give you time to sort it out Welcome to the forum Roger Hi Roger Thanks for your information. Yes thanks, I have seen the series of circuit diagrams and that is what I have been using to date. The 12v supply to the switch is via the G wire, the W wire is superfluous, other than heading up the same sleeve as the GY, GN into the heater box, and not connected to the switch at all. ie the wiring on the switch is totally consistent with the diagrams. Since my previous post, the blower is now running on speed 1, but not on speed 2, despite being 12v on both wires. Any thoughts welcome about what goes on in the heater box....unknown territory for me! I was planning to do the big ends etc when I next fill the washer bottle , a few quick jobs at the same time! But yes, I do feel like I ought to be out on the road rather than faffing under the dash! Thanks again David David Quote Link to post Share on other sites
TRbeginner Posted July 13, 2017 Author Report Share Posted July 13, 2017 David Useful diagram from Holden Vintage & Classic https://www.holden.co.uk/productImagesWD/34477.jpg You could slip some transparent insulation sleeves on the " spare " terminals but do check out the possibility of something else shorting it out. Bob Bob Thanks for the info - is that a schematic of this switch? I only have five terminals? I will slip some insulation over the two spare spades and check for other shorts. Will also rotate the switch through 90 as suggested by Neil. Regards David Quote Link to post Share on other sites
TRbeginner Posted July 13, 2017 Author Report Share Posted July 13, 2017 Common problem just rotate it so the pins are on the side. Neil, Thanks sounds like a common sense solution to a problem that I cant believe was designed in all those years ago. Will also put insulation on the spades. Regards David Quote Link to post Share on other sites
TRbeginner Posted July 13, 2017 Author Report Share Posted July 13, 2017 The reason there are unused terminals is because the switch will be used in a number of different applications such as lighting or wipers. Pete Thanks for this - obvious when pointed out, may be I need to open my mind a bit . Seems to be a risky item in terms of extra unused contacts shorting out though! Regards David Quote Link to post Share on other sites
TRbeginner Posted July 16, 2017 Author Report Share Posted July 16, 2017 Hi guys, Sorry if this is a bit repetitive, basic, or using a sledge hammer to crack a proverbial nut, but I still had misgivings about the heater wiring query above, so have take some voltage readings, reached a conclusion and would just like one or two second opinions before I put the dash back together please? In summary the problem was too many wires visible beneath the dash and heater not working. Green, Green/Yellow, Green/Brown all connected to the fan switch as per first image above, and as per the wiring diagrams for all TR5/6 variants I believe. BUT there is also an additional White wire, descending from the heater box and hanging loose with a ratty looking bullet connector going nowhere (see second image above). The fan didnt work on either speed. The third image attached shows the readings taken today at various IGN and Fan switch positions As far as I can see the fan switch is working as advertised (plus has 12v at the spare terminals, which seems to be an acknowledged safety issue). The fan didnt work initially, but I discovered accidentally (!) that when I earth the white wire, the fan operates. When the white wire is not connected to anything the fan stops (on both speeds). My conclusion is that rather than the white being a surplus later addition to the under dash wiring, it appears to be the earth for the fan motor. If this is the case then I have two outstanding questions 1) It seems odd that an earth doesn't conform to the usual standard of being Black, therefore a poor diy bodge? 2) There is no obvious earthing point for the floating bullet - wouldn't a factory standard be a black wire and be earthed inside the heater/fan box? Again an indication of a diy bodge? 3) I plan just to strip the corroded White earth wiring back a couple of inches, attach an appropriate connector and earth on the back of the dash panel, as I am trying to avoid removing the heater box at this stage. Any problems with this approach? 4) Tell me if I have missed anything please......?! As I said sorry if this is a bit elementary but I'm just trying to build confidence currently. Many thanks David Quote Link to post Share on other sites
stuart Posted July 16, 2017 Report Share Posted July 16, 2017 On earlier cars the white had a ring terminal and was connected to the rear of one of the top H frame to dash bolts to earth out. For whatever reason its always been that colour and its not a bodge, sorry didnt pick up this thread before hand. Stuart. Quote Link to post Share on other sites
Guest ntc Posted July 16, 2017 Report Share Posted July 16, 2017 Not as far as I know? it was green, white was live. Quote Link to post Share on other sites
TRbeginner Posted July 16, 2017 Author Report Share Posted July 16, 2017 Stuart - thanks for the reply - music to my ears, explains everything! Neil - thanks, are you suggesting earth was green? Interesting opposing view! Yes I also struggle to accept the white as the fan earth (defies all conventions) but pragmatically I cant put another argument together that holds water. Thanks both, David Quote Link to post Share on other sites
Guest ntc Posted July 16, 2017 Report Share Posted July 16, 2017 http://www.advanceautowire.com/tr2506.pdf Quote Link to post Share on other sites
TRbeginner Posted July 16, 2017 Author Report Share Posted July 16, 2017 http://www.advanceautowire.com/tr2506.pdf Neil Not sure what you're showing me - the diagram shows G (live - from the fuse box, via the voltage stabiliser)) and GY/GN (to fan motor) plus B earth - for all TR5/6 variants . Which is how I described it above except that my earth appears to be W, which Stuart believes was the case for some cars. If my interpretation of the diagram is wrong, it would be helpful to know where? Apologies if I have misinterpreted your thoughts. Thanks David David Quote Link to post Share on other sites
Guest ntc Posted July 16, 2017 Report Share Posted July 16, 2017 Stuart knows more than me however having owned a few 5/250 and 6's never seen a white wire used as earth. Quote Link to post Share on other sites
RogerH Posted July 16, 2017 Report Share Posted July 16, 2017 Hi David, the standard convention for Lucas wiring is that WHITE wires are for Ignition live. There is no way that I can say Stuart is not correct so before bolting the white wire down check to see that it is not live. Roger Quote Link to post Share on other sites
Guest ntc Posted July 16, 2017 Report Share Posted July 16, 2017 http://www.tr-register.co.uk/forums/index.php?/topic/28353-heater-fan-switch/ Quote Link to post Share on other sites
TRbeginner Posted July 16, 2017 Author Report Share Posted July 16, 2017 Roger/Neil There is only 12v on the white wire when the Ign is ON, AND the Fan switch is also ON (slow or fast speed) at the same time. The Green always has 12v when the Ign is ON regardless of Fan switch position. Please see test data in image higher up thread. Does this change anyones views about the status of the whote wire? I also measured 0v on the switch body in all settings. I have only tested the voltages while the switch is hanging free and not in situ. So perhaps this is the next step given the info in the thread. I am aware that the rotation of the switch in situ can cause shorting problems and have yet to deal with this. Thanks David Quote Link to post Share on other sites
RogerH Posted July 16, 2017 Report Share Posted July 16, 2017 Hi David, 'if' the white wire is an earth wire then with it NOT connected to earth and the IG and Fan ON then the white wire will read 12V. If the white wires is then earth'd its volts will drop to 0V and the appliance start to work. If it is an Ignition live wire then a fuse will pop. Roger Quote Link to post Share on other sites
Guest ntc Posted July 16, 2017 Report Share Posted July 16, 2017 Hi David, 'if' the white wire is an earth wire then with it NOT connected to earth and the IG and Fan ON then the white wire will read 12V. If the white wires is then earth'd its volts will drop to 0V and the appliance start to work. If it is an Ignition live wire then a fuse will pop. Roger Yep And David just had a look and that is not std wiring Quote Link to post Share on other sites
TRbeginner Posted July 16, 2017 Author Report Share Posted July 16, 2017 Roger, Thanks, your last message, first para, describes exactly what is happening. Re the second para when the white wire is earthed, the fan starts to work. However I havent yet measured voltage when the white wire is earthed and the fan is running. Will do that tomorrow. The only times fuses have blown is when the switch was mounted. I think the two spare live terminals on the swtich were shorting on the local metalwork. I havent yet rotated the switch to avoid this. Dave Quote Link to post Share on other sites
RogerH Posted July 16, 2017 Report Share Posted July 16, 2017 Hi David, with the white wire earthed and the fan running the white wire voltage will be 0V. And thus Stuart does it again - pure genius. Roger Quote Link to post Share on other sites
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