Neill Solomon

It is a 1986 300zx NA with 70K miles on the original engine. Car is in amazing shape! All electrical works properly except that the front marker lights are completely unresponsive. I have replaced both bulbs but that was not the problem. It seems to coincidental that it is both of them. I have looked at the Haynes and the Service manual but for my skill level I can see anything that would affect only the side markers.

Do you know anything that would affect only them?

Side note, when I step on the brakes the voltage gauge goes down is that normal or should i be looking for a short?

Thanks,
Neille

zxguy1986

If the 'marker lights' are the yellow ones on the front quarter panel sides, their power supply needs to be traced back with a multimeter to the harness connections. First check all your fuses. Then check your FSM electrical diagrams EL-53-54, etc. (factory service manual - It's a freebie from http://www.xenonz31.com/reference.html) Start at the bulb sockets to see if they are powered. If not, then work backwards one connector at a time to see where the break is. Sorry but there's no shortcut for this. Weird that they both are out at the same time. Sounds like a dirty connector issue right at the point where their power feeds split - which means a harness connection just this side of the light stick on the steering column. It's all in your elec diagrams. Yeah, they're a pain to follow. (I use colored markers and trace the feeds on 11x17 printouts I got from my local copy shop. They stay with my manual for future reference.)

If your belts are tight, the voltage gauge is telling you that your battery/charging setup needs to be tested. Battery-selling places will do that for free. Your alternator needs to put out over 14v while charging the battery/running stuff. Check that. If it's less, your alt is dying. Replace it. Also your battery may be old and not holding its charge well. Check all your batt/alt cables and connections. Dump the crappy batt terminals and get good ones. If you get a new batt, get one with more cold crank amps than your Z requires. Z31s need very reliable electrical power every minute or stuff starts acting weird all over the place. It will make you crazy looking for problems elsewhere - when it's just your DC power supply