Mike B75 Posted July 24, 2021 Report Share Posted July 24, 2021 Hi All, Car is 1981 TR7 converted by Grinnall to V8 in 1988. I've had a problem with my nearside sidelights, which are now currently working but I have no dashboard and instrument panel lighting. It seems the feed is a red wire to the dashboard mounted rheostat, from which a couple of red+white wires run, which split into further red+white wires to all interior/dash bulbs. However I have no power at the original red wire feed to rheostat. This feed is supplied by the nearside sidelight circuit. The wiring diagram suggests there is a single red wire from the 15A fuse that supplies the NS sidelight circuit, which then splits 3 ways, to front and rear sidelight and to the feed to rheostat and then inst panel lighting. I suspect there is a problem where these 3 wires split. I am guessing there will be a connector behind the fuseboard, relay board or glovebox. I can see there is a whole mass of wiring there. I can unclip the fuseboard from it's holder but I cannot get enough movement to see anything behind there at all. A friend of mine happened to get the nearside sidelight circuit working when he was investigating the fuseboard and that specific fuse. I would like to examine that mass of wiring behind the glovebox and trace the red wire back as far as I can to it's fuse. Can anyone offer me any help or advice in how I go about doing this, including how to get it all back together again please? I can see there is a metal plate behind the glovebox, I guess it's this I need to remove or get into? Looking at it it all appears quite daunting but I really feel I want to take a look into there. I would appreciate any help or advice anyone can offer, thanks in advance, Mike. Quote Link to post Share on other sites
HowardB Posted July 24, 2021 Report Share Posted July 24, 2021 Its a real birds nest behind there and I am reliably informed that the easiest way is to remove the entire dashboard to access everything... However if you don't want to go to that extreme, I had to modify the supply to my instrument light cct. The original red instrument feed cable had been disconnected by a previous owner near the rheostat & a new supply jury rigged to feed the instruments. Last year I decided to sort it all out and discovered that there was a fault on the original red feed wire which was shorting to earth. With care its possible (easier if its a DHC) to remove the centre heater console & feed to red wire back to behind the fuse board - I managed to move the fuse board and cut the defective wire close to the fuse, but it would have been easier to cut if from underneath the dash (accessible by lying on your back with your head under the dash and feet in the air ) I spliced in a new cable and added a the red 10A modern fuse you can see on the right of the photo to provide a new supply. Hope this helps - I have also attached a redrawn wiring diagram that may assist you Howard UK DHC 1980-81 TR7 (2020-09) with pektron fuel gauge & fan details.pdf Quote Link to post Share on other sites
Mike B75 Posted July 24, 2021 Author Report Share Posted July 24, 2021 Hi Howard, That looks like something I may have to do, but can I take this opportunity to say thanks very much for the wiring diagram, that is an incredible piece of work and has been immensely helpful. Thanks very much indeed. Quote Link to post Share on other sites
HowardB Posted July 24, 2021 Report Share Posted July 24, 2021 Mike, where are you based? I am located in East Beds. H Quote Link to post Share on other sites
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