73 dash lamps
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Joined: Dec 2017
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From: Monroe NC
73 dash lamps
Hey guys, I need some help with the instrument lamps on my 73. None of them burn, I checked the fuse which was good (replaced anyway) and checking the voltage I have 0 volts on either side of the fuse. The head light indicator works and the kick panel lights come on when I turn the head light switch to the full left position. Where do I check next?
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Joined: Dec 2017
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From: Monroe NC
73 dash lamps
Checked all the other fuses and they have 12 volts across them. Tried rotating the switch from full dim and to full bright, with no change. According to the wiring diagram the inst lights are on the small 5amp fuse at the bottom of the panel.
Le Mans Master
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From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2019 C3 of Year Finalist (appearance mods)
If the dash lights go on then the rheostat in the head light switch is bad.
Burning Brakes
Joined: Sep 2005
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From: Lewes Delaware
Fuse may be bad or there is corrosion at the holder. Also check wire connections to the holder. Take out the two lights that do not work and test them. Replace if burned out. Otherwise, check for corrosion/loose connection at the sockets.
Fran
Fran
Le Mans Master
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From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2019 C3 of Year Finalist (appearance mods)
Pulling the light switch to the first or second click sends power on the GREEN wire into the fuse.
Power comes out of the fuse on GRAY wires and sends power to ALL the bulbs.
Could you have corrosion where the GREEN connects to the switch or at the fuse connection?
Could you have a break somewhere on a GRAY wire?
Have all the bulbs lit up ever before?
Wild guess, are all the bulbs bad?
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Racer
Joined: Jan 2013
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Since your instrument lights work (with the exception of speedo and tach) when running a positive wire to the fuse that tells you your ground is good to you "gauge plate" ( the gauges are mounted to a metal mounting plate) and the wires are good to each bulb that lights. So you have a power problem, either at the headlight switch or out of the headlight switch. I can speak to the gauge lights only as I've got mine working (not speaking to tach or speedo). The lights for my 73 have a single gray positive wire to each socket, ground is made from the socket tangs that hold the socket into the metal gauge plate which is grounded. So, either wiring issues from switch to fuse, switch issue or input issue to switch. Your tach and speedo could be as simple as burnt out lights or something related to the gauge lights. Lots of luck, Russ
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From: Monroe NC
OK goys tomorrow I am pulling the head light switch and running a 12 volt source to the green feed and see if we get lights. My assumption is if the lights come on it points to the switch if not the fuse block.
Le Mans Master
Joined: Aug 2006
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From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2019 C3 of Year Finalist (appearance mods)
Make sure you reconnect the vacuum hoses correctly.
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Joined: Dec 2017
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From: Monroe NC
OK changed the switch and created a set of new issues. the dash lamps come on but burn all the time unless you dim the switch as far as it will go. makes no difference if the lights are on or not, Also the tail lights burn all the time.
Racer
Joined: Jan 2013
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Grumpy73,
Sounds like a possible issue with your new head light switch. If the switch is not internally wired correctly or the switch is not the correct one ( I remember two different switches being listed for early VS later C3's) then that could be an issue. Did you try out the new switch before you re-assembled things back together? Where did you get your new / different switch from? Might be worth talking with the supplier about your issues. I changed my headlight switch but used a NOS Delco I bought off eBay. It was fairly reasonably priced (paid about $70 including shipping) tried it out before fully re-assembling and then buttoned things up. The new switch fixed my gauge lighting issues. Keep updating with any new developments. Lots of luck, Russ.
Sounds like a possible issue with your new head light switch. If the switch is not internally wired correctly or the switch is not the correct one ( I remember two different switches being listed for early VS later C3's) then that could be an issue. Did you try out the new switch before you re-assembled things back together? Where did you get your new / different switch from? Might be worth talking with the supplier about your issues. I changed my headlight switch but used a NOS Delco I bought off eBay. It was fairly reasonably priced (paid about $70 including shipping) tried it out before fully re-assembling and then buttoned things up. The new switch fixed my gauge lighting issues. Keep updating with any new developments. Lots of luck, Russ.
