I have power to starter, alternator, and horn relay but no power to fuse panel. In-line fuses look ok and when I turn on the headlights they don’t turn on and I lose power to the alternator and horn relay. Can’t figure it out driving me crazy. The car is a 1968😎 I should mention I put a new a new engine wiring harness on it and it ran fine but when working on the headlights I shut off the car and forgot to turn the lights off after that is when I had the problem.

Wiring diagram shows 2 fuse links in the circuit that goes to the fusebox/firewall passthru. One is down by the starter, brown wire on the starter end, then it changes after the fuse link to a red wire. That red wire goes up to the horn relay/power junction. It ALSO t-ees off to the fuse box, with another fuse link in a splice, orange wire on horn relay side, changing to a black wire on the fusebox side of the fuselink. Just looking a a fuse link will not tell you if it is good. You need to check voltage on BOTH sides of the link. On the horn relay/junction is another fuse link wire that goes thru the fusebox to the ammeter, orange wire at the horn relay, turning into black after the fuselink, then thru the fusebox thru the ammeter.

Check ALL of the fuselinks with a voltmeter on BOTH sides. ALL of these wires should have battery voltage at all times, key on or not. If all of the fuselinks check good, then I would suspect the firewall passthru has been compromised with corrosion, or heat. Happens a lot on these old cars like this. 

Of course, all of this assumes the battery itself, and it's connections are good, including the grounds from the battery tot he frame under the driver seat, as well as the ground from the frame to the engine mount on the passenger side. 🙂

Joel Adams
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Thanks I’ll check it out tomorrow 😎

Now I have power to the fuse panel but if I turn the key to start or I put the brake lights on or pull the light switch out I lose power to the fuse panel. Any answers? Thanks 

You have a loose, or corroded connection somewhere, that is not allowing the amperage needed to pass thru it. I would suggest starting with the basics. Check battery( + & - ) connections, from the battery to the starter. Take them off and clean them, even if they look OK. From there, you just have to go down the line and check every connection from the starter up to the horn relay, the to the firewall passthru/fuse box connection. 

If the new engine harness is all you replaced, I would highly suspect that your problem is going to be in the firewall passthru. Make sure the bolt is tight. Maybe even disconnect it and see if there is an obvious issue with any of the terminals in that connector. Not easy to do, considering the location, but my feeling is the problem is in that connection. 🙁

Joel Adams
C3VR Lifetime Member #56    
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"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"

Thanks I’ll try the bulkhead hopefully that will help.