Hey guys, here's the story..need some help..

I have a 71 240z. Stock (mostly). Prior owner installed the parking light upgrade with 15 amp fuse link coming from battery positive terminal. I just upgraded the alternator to a 60 amp. Disconnected the old voltage regulator and capped with the diode connector from motorsports. Everything was and is great! Car runs better. Charging well. Starts easy and no problems when I got everything hooked up. About 30 minutes into my drive back home after connecting everything at my friends shop. The dash lights went out (and the side and rear parking lights). Headlights, high beams, turn signals, dome, hazzard, lighter, radio, power antenna, ignition buzzer, brake lights are all functional. I checked fuse link for parking light upgrade and it was blown. Replaced it and everything worked. Next day, still worked in the morning. Then at night, blew fuse again. No other fuses are blowing. It happens whether car is running or not. Just the fuse for the parking light upgrade. I don't think it's the alternator upgrade, just coincidence, or I grounded something during install? Or connections to turn signals/parking lights have grounded? Any ideas of where I should start.thanks

Forgot to add one important piece of information. This happens only when I turn headlight knob forward to activate parking lights, or headlights, no other time..

Check the light sockets for corrosion. The side markers can get corroded as the gasket gets old and leaks.

You might also consider moving to LED lights. They draw less power.

Check the light sockets for corrosion. The side markers can get corroded as the gasket gets old and leaks.

You might also consider moving to LED lights. They draw less power.

Thanks!

Doing that tonight.

I'll let you know if it works!

If it keeps blowing, then we'll go into full diagnostic mode by pulling connectors to isolate the part of the circuit giving you problems. You wouldn't happen to own a multimeter and know how to use it by any chance?

If it keeps blowing, then we'll go into full diagnostic mode by pulling connectors to isolate the part of the circuit giving you problems. You wouldn't happen to own a multimeter and know how to use it by any chance?

Yes I do.

Thanks.

I think I may have found the culprit.

Drivers side marker..bulb is rusted in the connection. Completely corroded. Passenger side bad took..I'm going to check rear markers as well..if they are bad, I'll clip and cap all and try again. I'll post some pics when I get back to the garage. Thanks!

If necessary...

Datsun 510 120Y B210 240Z Side Marker Lamp Red Amber | eBay

Thanks..necessary..

Thanks for the advice guys. It was the front running lights. Drivers side corroded really bad. Passenger side less, but not worth repairing. Rear running lights were brand new. Prior owner must have replaced. Cut, capped, new15a fuse.

Everything works..dash lights, rear running lights and rear tail lights when headlights are on. Now to order some new ones! Thanks again.