# Clearance Illumi Fuse Keeps Blowing



## Theonlymogly (Aug 4, 2020)

This is my first post on here and i dont know EXACTLY where to put it. Just bought a 1987 300zx non turbo a little while ago and it has quite a few problems. Starting with the fuel pump, electric radiator fans and the injectors all being on switches and a poorly wired radio. Since then i have fixed the radio wiring. Its all correct now and does not use anything connected to the Clearance Illumi fuse. But the fuse will blow about every 20 minutes. Everything operates just as it should when the fuse isnt blown. Ive tried all the way up to 30 amp fuses to no avail. It acts fine and all of a sudden when i try to turn it on after turning it off the fuse blows. I dont know much about these cars just yet and was wondering what all i should check before i go crazy looking for a short. Somebody has also cut into the stock wiring for the tail lights and used crimp connectors. And the reverse lights do not work to my knowledge. But is there any pointers on where to look for a short in these cars? Thank you!!


----------



## rogoman (Dec 16, 2004)

First thing is to inspect the area that was cut into; look for bare wires in the harness that could possibly short out. I've included two wiring diagrams; depending if the car has "stop and tail lamp sensors" or does not have the sensors.

To start trouble shooting, disconnect the battery on the negative (-) side. Next pull the 15A clearance illumination fuse. Following the diagram - starting from the end points working back toward the 15A fuse holder; start disconnecting harness connectors along the way and remove all the bulbs - testing for shorts on the disconnected legs. Use an ohmmeter for continuity testing. With the test leads; clip the negative probe to a ground point; use the positive probe on the disconnected legs looking for shorts; while testing, wiggle the harness and lamp holders.


----------



## Theonlymogly (Aug 4, 2020)

rogoman said:


> First thing is to inspect the area that was cut into; look for bare wires in the harness that could possibly short out. I've included two wiring diagrams; depending if the car has "stop and tail lamp sensors" or does not have the sensors.
> 
> To start trouble shooting, disconnect the battery on the negative (-) side. Next pull the 15A clearance illumination fuse. Following the diagram - starting from the end points working back toward the 15A fuse holder; start disconnecting harness connectors along the way and remove all the bulbs - testing for shorts on the disconnected legs. Use an ohmmeter for continuity testing. With the test leads; clip the negative probe to a ground point; use the positive probe on the disconnected legs looking for shorts; while testing, wiggle the harness and lamp holders.
> 
> ...


Okay, so i unplugged all the harnesses for every running light around the car. The headlight motors are fine. But as soon as i flip the switch to turn on the now unplugged DRL lights it blows the fuse. Instantly. What all is run on this fuse and could it be the switch? Thank you for that wiring diagram, it helped alot.


----------



## rogoman (Dec 16, 2004)

To save popping fuses, I would use an ohmmeter for tracing a short.
If you follow wire R/L (Red/Blue) from the 15A fuse, the very next thing it goes to is the lighting switch. Unplug the lighting switch and measure continuity from the R/L wire to ground; it should be infinite; if not, there's a short somewhere along the wire. So at this point if the reading is infinite, plug the lighting switch back in and measure the continuity again; if you're getting zero, then the switch may have a short in it or else there's a short in the wire R/G (Red/Green) coming out of the switch feeding the components.


----------



## Theonlymogly (Aug 4, 2020)

rogoman said:


> To save popping fuses, I would use an ohmmeter for tracing a short.
> If you follow wire R/L (Red/Blue) from the 15A fuse, the very next thing it goes to is the lighting switch. Unplug the lighting switch and measure continuity from the R/L wire to ground; it should be infinite; if not, there's a short somewhere along the wire. So at this point if the reading is infinite, plug the lighting switch back in and measure the continuity again; if you're getting zero, then the switch may have a short in it or else there's a short in the wire R/G (Red/Green) coming out of the switch feeding the components.


I actually got around to taking apart some things today and took out every single bulb that illuminated on the outside of the car. One at a time and bought a pack of 25 fuses. It ended up being a ground on the radio that was already wired in. I thought it was the stock ground wire so i didnt touch it. It was actually a live wire. But i grounded the radio in a different location and everything works as it should now. I just need to fix the speedometer and my reverse lights next. Odometer doesnt count up either. But thank you.


----------

