smh00n 87 Report post Posted July 16, 2021 Being in Australia, we have a crazy law that requires both stop lights to be illuminated together - so the red indicator function needs to go. Where in the loom does the indicator/stop light happen? I'll try to split the wires and put in a separate bulb for the indicator. Quote Share this post Link to post Share on other sites
Midlife 814 Report post Posted July 16, 2021 Turn signal and stop lamps are combined together in the turn signal switch. There's no easy way to disentangle the two when the two signals share the same filament. The stop lamp signal is a green wire, 2nd from the end on the bottom interior curve. The rear turn signal leads are green/orange (left) and orange/blue (right) at the turn signal switch. Quote Share this post Link to post Share on other sites
smh00n 87 Report post Posted July 16, 2021 Thanks. So, do the stop light wires go through the turn signal switch? Would it be easier to run a new wire to the stop lamps? I was thinking that I could put in a divider inside the bucket/housing for the outer lens of the lamp, and use the outer third lens as the indicator light (I can use a red indicator lens) and use the inner two for stop lamps, again with a new holder to brighten them up. Would that be less effort? I'm a bit sick of idiots nearly rear-ending me due to being on their phones and dim stop lights not really indicating when I am stopping. Quote Share this post Link to post Share on other sites
Midlife 814 Report post Posted July 16, 2021 I'm not sure that would work. Yes, you can bypass the turn signal switch for brake lights, and convert one bulb to turn signal only and the other to brake lights. The problem lies in the side marker lamps which don't have a true ground, but compare voltage of turn signals to running lights. Quote Share this post Link to post Share on other sites
Mach1 Driver 560 Report post Posted July 16, 2021 Maybe bigmal will drop by here, or you can send him a message. He also lives down under and has a 70. I have a post here that describes the 70s turn signal system, and he said it helped unscramble the problem. Perhaps he can guide you through what he did. Look in "How to's" for "1970 Mustang Exterior Lights (turn signals)". 1 smh00n reacted to this Quote Share this post Link to post Share on other sites
pgold 2 Report post Posted July 24, 2021 Have a look at this conversion thread for 66 using reverse lights for indicators ( turn signals ). https://forum.mustang.org.au/index.php?topic=27150.msg336845#msg336845 Quote Share this post Link to post Share on other sites
smh00n 87 Report post Posted July 25, 2021 Pgold that's similar to what I was thinking. I'll have to get time to look at the whole set up and see how I can change it. I'm thinking maybe change the side lights to just marker lights. The whole 70 alternating indicator and side light thing has stumped me, and now may explain why the repro front indicators I used seemed to not work properly. The indicator bulb was on at park and the side light bulb flashed (basically, reverse of what should have happened) so now I need to spend some time thinking this through. One of the joys of buying another mans project :( Quote Share this post Link to post Share on other sites
Midlife 814 Report post Posted July 25, 2021 31 minutes ago, smh00n said: Pgold that's similar to what I was thinking. I'll have to get time to look at the whole set up and see how I can change it. I'm thinking maybe change the side lights to just marker lights. The whole 70 alternating indicator and side light thing has stumped me, and now may explain why the repro front indicators I used seemed to not work properly. The indicator bulb was on at park and the side light bulb flashed (basically, reverse of what should have happened) so now I need to spend some time thinking this through. One of the joys of buying another mans project :( That problem is due to a very bad design issue by Ford (which was corrected in following years). There are no true grounds for the side marker lamps, instead the lamps light up when there's a difference in voltage between the turn signal and the running lights. This means that the turn signal lines or the running light lines act as a ground and that there is voltage/current bleed-through from one to the other. This makes trouble-shooting near impossible. Bad Boy, Ford, Bad Boy! Quote Share this post Link to post Share on other sites
smh00n 87 Report post Posted July 26, 2021 On 7/25/2021 at 11:19 AM, Midlife said: That problem is due to a very bad design issue by Ford (which was corrected in following years). There are no true grounds for the side marker lamps, instead the lamps light up when there's a difference in voltage between the turn signal and the running lights. This means that the turn signal lines or the running light lines act as a ground and that there is voltage/current bleed-through from one to the other. This makes trouble-shooting near impossible. Bad Boy, Ford, Bad Boy! The Fraud Motor Company outdid themselves on this one alright. I stripped back the harness on the driver side yesterday - soooo many black wires! I think I have identified the wiring I need; it turns out the PO had already run a new brake light wire and has hacked up the OEM harness, so I believe I can just cut one wire and put it to the new indicator bulb. Watch this space. Quote Share this post Link to post Share on other sites
smh00n 87 Report post Posted November 29, 2021 Another question - what sort of voltage should I see at both stop and tail lights, at the rear lights? I checked yesterday and I'm seeing about 10.5v on the stop and closer to 11.0v on the tail. It does change a bit with engine revs which I didn't think would happen (?). I suspect the stop light circuit is not correct as there is some replacement wiring, and it may be higher resistance than OEM but knowing the 'correct' voltage will make it easier for me. Quote Share this post Link to post Share on other sites
Mach1 Driver 560 Report post Posted November 29, 2021 I couldn't give you a number but your results don't seem shocking. The brake light circuit starts at the headlight switch, goes through the brake switch, through the turn signal switch, through a plug and to the brake light filament which is more than four times the load of the tail light filament. I expect less voltage there. The tail lights start at the headlight switch, and only go through one plug and as I said the filament draws less than 1/4 the amps. Quote Share this post Link to post Share on other sites
smh00n 87 Report post Posted November 29, 2021 (edited) Thanks. I am converting the lights to LED and was going to use 10.0v as a reference for the load, but today I checked all the wires for voltage and somehow the voltage has now jumped to 12.5 on both light circuits. Dunno how I changed it, definitely some elec-trickery going on. At least now I can go forward with my lights and power box and not have to start again. I'm building the lights myself and not use a commercial unit. Edited November 30, 2021 by smh00n Quote Share this post Link to post Share on other sites
