What are best steps to take to determine why none of my side marker lights work when headlights or turn signals are on. Any ideas?

Thanks!

Same as any light. Start at the bulbs and work backwards. Test the bulbs themselves, check to see if you have power getting to the socket, and check the ground for rust and corrosion. If everything looks and tests good at the light itself, start moving farther back up the circuit testing as you go.

Side note - the Datsun sidemarkers only work with the parking lights, they did not flash with the turnsignals.

Thanks, Arne, simple advice seems to work the best!

What is best source for new marker lights and gaskets? Once I get mine to work, need to replace a couple of mine.

Thanks!

Try MSA, Victoria British, Too Intense Restorations, etc...

I found that Victoria British has better pricing on Side marker gaskets, front turn signal gaskets & tail light gaskets. And oh, their price on the rubber gas door flap is also a lot cheaper.

Side note - the Datsun sidemarkers only work with the parking lights, they did not flash with the turnsignals.

couldnt u get them to work by wiring it to the rear tail lights for the rear markers and the markers in front to the front side markers? then that would make the side ones blink too. should anyway. im gona try to make them work. also i was having the problem where when i turn the signals on and everything is flashing outside but the dash lights dont blink. the lights in the dash work when i turn the warning signals on thou. any ideas what this could be?

As far as blinking side markers, you'd need dual filament bulbs in order to have the regular running side markers when they aren't blinking. I've never seen a dual filament bulb of the type that fits in the side markers and if you used a larger bulb you'd probably burn the lenses. The other problem is most likely in you turn signal switch such as a bad contact in the area that sends that signal to the dash lights.

Nah, you could make them blink with a relay or two. If the lights were off, they'd blink with the signals. If the lights were on, they'd blink opposite. It can be done, but it's probably more trouble than it's worth, especially on a 240 where the normal turn signals wrap around the side anyway.

in the roadster and 510 worlds, the method used the make the front marker lights blink is to route the ground through the turn signal hot. Thereby, when the turn signal turns on, it interups the ground path for the marker and it turns off. This included replacing the SS marker housing screws with plastic screws to isolate from ground.

Ahh! i found the artical!

http://dimequarterly.tierranet.com/articles/tech_lite.html