1985 Suzuki SJ410. When I put the gear to reverse and turn the key to on, the dash lights won't come on, and even though the starter will run, engine won't ignite.

I recently also had problems with the brake lights (none of them worked), but it suddenly started working again.

I suspect a grounding issue, and I think maybe the wires/fuses for ignition/coil and reverse lights share the same ground? Anyone know where I can find this grounding wire?

I suspect a grounding issue, and I think maybe the wires/fuses for ignition/coil and reverse lights share the same ground? Anyone know where I can find this grounding wire?

They don't share the same ground - but they do share a common power source - they are fed from the ignition switch - grab a test meter or test light and start troubleshooting.

I have no experience with electrical issues on a car - anyone know exactly where to start to look, and what to look for? I already checked all grounding wires in engine bay.

When dashlights are on, they will turn off if I put the gear in reverse. But not always. If I put it on off again, shift gear etc, I can sometimes put it in reverse without lights going off. And whenever I have lights on, car will also start.  Whenever no lights, starter will run, but engine will not start.

I have no experience with electrical issues on a car

The best advice I can give you is find someone who does - you cannot troubleshoot the problem if you don't understand how the system operates, swapping parts is going to get "real expensive, real quick".

When you say "dash lights" - what specifically are you referring to - the illumination lights that light the gauges so you can see them at night, or the dash warning lights - charge light, oil pressure light, etc. - if it is the warning lights, the problem more likely than not is the power feed from the ignition switch - a bad connection, a broken wire, etc..

When you say "dash lights" - what specifically are you referring to

I mean the warning lights. But if the ignition switch power is the problem, why will the starter motor, always run fine when I turn the key?

This is the exact reason I suggested you find someone who knows how the system works...

Power from the battery will flow through the fusible link to the ignition switch, there will be at very least three (usually four) separate switch sections in the ignition switch assembly - the first will be closed in the ACC & ON switch positions, but is open in the START position, the second will be open in the ACC position and closed in the ON & START position, and the third will be open in the ACC & ON positions and closed in the START position - if there are four, the fourth will be closed in the ON position and open in all others.

Any one of those switch sections could be defective and the remainder fully functional (it's quite common for section three to be problematic) - if the section two was worn or defective and making contact intermittently, you would have the exact symptoms you are experiencing now - the "downstream" wiring connected to that switch section goes to the fuse panel and then to the separate circuits - the wiring between the ignition switch and the fuse panel or the fuse panel itself could be defective, and you would have the exact symptoms you're describing.

Without a wiring schematic for the vehicle, I can't tell you if the affected circuits are protected by one or more than one fuse, but if it were one fuse, then the wiring downstream from the fuse panel could also be defective.

You're looking for a needle in a haystack, and because you lack the experience, you wouldn't recognize the needle even if you were looking directly at it.

Thanks for the reply... I'm not completely clueless on electrical work, but this issue seems a little bit strange to me. When the gear is in reverse and I turn the key to "ON" the dashlights will usually not turn on immediately - but after maybe 3-5 seconds, they usually turn on. All other gears, it turns on instantly. I don't understand what could cause this delay 

When I meassure the ignition wires, I get between 11.5v and 12v. That is a bit too low, isn't it? (meassured at battery, the voltage is higher/normal)