Very Frustating Electrical Issue with lights

[Lazeum]

I'll try to summarise my problem in a short way.

 

First of all, my headlight are modified to meet Euro specs i.e. white/yellow position lights instead of the stock US orange ones.

So I've got some Hella H4 housing with position lights included. I had to reroute the position light wire to the housing and get some ground. I've spiced position lights ground with headlight ground.

I has worked good with no problem at all for over one year with everything functionnal.

 

 

So my problem as of today: I keep blowing up fuses each time I turn the lights on!!!

 

 

1st issue:

When I turned the headlights on, both left & right headlight fuses blew; I had no more headlight at all.

So I've checked if I could have some shorts with an ohmmeter between wires, wire/ground. I found 0 problem.

I decided to clean up the headlight switch, I know it has a tendancy to fry because of high current going thru it. I've also check at that time every connections I could; cleam them up & spray some WD40 into them.

 

I had got some very weird result:

When I was turning the lights on, they turned on, 1 or 2 seconds after the right fuse only blew up. The right headlight turned off before turning on again (!!!!???!) couple of seconds after.

 

2nd issue:

I remembered the way I've ground the position light. I thought that headlight could get the ground out of position light. So I've disconnected the harness for the pos. light. I was able to turn on the headlights with no fuse burning out or what so ever.

Next step was to understand what went wrong with the pos. light so I've tried to change bulbs since those can also be bad.

 

I'd started with right hand side which used to blow fuses, I've made the trial with the bulbs hanging down. Everything was working as it should!

I'd done the same on the left side to get the same bulb ref. on both sides, everything went alright.

 

I then reattached everything up with screws. I've made a test. This time the 20A fuse for the position lights, tail lights, side lights blew up!!!

 

Next step?

So 3 different kinds of fuses had blown since I started looking for the root cause. Each time it happens I'm not able to explain why!

and why everything works when everything is hanging while it does not when everything is properly attached????

 

Of course, I'm checking what kind of connection could have created such a result. So I've isolated every light housing as much as I could. I also check if bolts were not long enough to touch something they should not (apparently, everything is ok).

 

I run short of fuses; I blew at least 20 of them during my experiements. So I stopped so far for this time being, I will continue next WE.

 

I'm writing this to know if this happened to some of you. Maybe you'll have some explanations or some tips to help me sorting this issue out.

 

 

I have to go to Le Mans Classic in July which is a revival of the 24hrs with only classic cars. I cannot miss that!!! We do have a Datsun club stand, I cannot come with my DD whereas the Z is almost there

 

 

 

=> I know also I should add the relays in my system but it seems to me relays won't solve the issue anyway, the way it is now.

 

=> the summary has been far away from being short I'll do better next time!

[Tony D]

Add the plug-n-play relays for the headlamps and divorce the high load totally off your chassis wiring harness.

 

Likely what you have is a broken wire insulation that is grounding and shorting when in place, but not when hanging. Find that, then relay it to stop the high load through the switch!

 

My wife's Y2K Navara was toasting the left headlamp socket due to poor grounding by Nissan. No matter what I did I could not get that thing to work and it kept killing lamps.

 

So I took the one good right socket and used it to trigger the relays, putting a resistor on the left plug permanently to keep the 'headlamp check option' from saying one headlamp was out. Worked like a charm.

[Lazeum]

Relay upgrade would be a must have for sure! Even if my lights on my car (when working) are very good (way better than my DD - a Silvia S14a)

 

I'll continue looking for the short, it is somewhere for sure! it is around the lights, it should become quite easy to spot, even if I've failed for the moment...

Maybe I should also look at ground connection, something could be loose somewhere creating this intermittent issue.

 

I'll work on it this weekend, hopefully I can report back and close this issue

 

 

Thanks for the reply btw

[PapaSmurf]

my 78 has some serious wiring issues as well. I finally got all the marker lights working the other day but my headlights would only work on bright for years until I went through my fuseable box, the fuseable links were replaced with some large fuses that I can't find any information about. It's in a clear open to air (and water) box that just sucks. I fiddled with it, cleaned up the wiring made sure everything was making good contact, then tested the headlights and now they only work on dim!?

 

So I'm here to tell you I know how you feel, 30 year old electrical systems are a pain in the ass.

[Lazeum]

my 78 has some serious wiring issues as well. I finally got all the marker lights working the other day but my headlights would only work on bright for years until I went through my fuseable box, the fuseable links were replaced with some large fuses that I can't find any information about. It's in a clear open to air (and water) box that just sucks. I fiddled with it, cleaned up the wiring made sure everything was making good contact, then tested the headlights and now they only work on dim!?

 

So I'm here to tell you I know how you feel, 30 year old electrical systems are a pain in the ass.

Your story seems as odd as mine   Good luck with your! Have you check for instance Resistance for all fuses/connections on the box? That could lead to some solutions ...or not (like mine  )

 

 

I'm going to pick up some more fuses and continue my investigations today. For you rinfo, I've got 2 fuse boxes (the ones below the choke/windshield lignt) but both looks and not corroded at all.

 

 

[Lazeum]

I think I found the origin of my problem today!!!     

 

I was unable to get a lot of new fuses (20A does not seem to be so common over her in Europe), So I had 2 and move forward with smaller steps to get the all potential root cause out of the picture until one failure occurred (kind of "5 why" methods).

 

 

Fuse blew only when I was attaching the side lens housing to the body, otherwise it was fine. So I start looking for color on wires and I found out the previous owner did a home-made harness with inappropriate colors (ground = Red, 12V = Yellow, butt plugs) and get stuffs mixed up. I've compared both sides, they are opposite. Basically 12V signal goes on the housing of the lens in my car (and only on 1 side)   

 

I guess plugging 12V signal on the body is a bad idea   

 

 

 

 

So I'll redo the harness the proper way and give it a try but everything was working very well today when lights was hanging. So I'm confident it's a done deal!   

 

 

 

 

My problem is I don't understand how the car was working before? Could have I messed around with the wires at one point? It is very plausible but I don't recall. I cannot either explain why symptoms have been so erratic with the Z. Hopefully the issue is behind me now since I've checked all connections, greased everything to prevent failure/rust, all fuses are new (!!!) and switches have been cleaned up.

 

I just need relays now!

Edited June 13, 2010 by Lazeum

[Lazeum]

I just wanted to let you know, everything is now working very well I've put 15A fuses instaead of 20A since I couldn't find any.

 

I don't think I've been dealing the right way with electronically issue.

I should have removed all the bulbs from my car, check if fuse was still blowing with no bulb, that would have meant problem was with wires.

I should have afterwards put bulbs one by one until I'd have blew a fuse. It would have been much quicker than guessing and trying to solve unproven issue.

 

Anyway issue sorted, it was ignition switch corroded, NOK side marker bulb & wrong installation (wires mixed up) during the check up.

 

thanks for your help!

Edited July 2, 2010 by Lazeum

[Tony D]

Oh, side marker lights...

 

I feel your pain. To be sure, NISSAN made the sidemarker lights the ONLY non-idiot-proof connection on the body! They are the only lighting connector where you can directly connect power to ground.

 

I thought you meant something else in your description! I had the EXACT same issue on my 73 when I bought it. Right Rear Corner Marker was directly grounded, and it took a LOT of fuses to find that one!

 

It's where a 1 amp circuit breaker with a pop-out reset comes in handy. You can make them with a dowel, some metal tubing, wire and a standard pop style 12V circuit breaker. Makes troubleshooting shorts much less bothersome (I wouldn't say less expensive, fuses are CHEAP compared to a ceramic bodied aircraft style circuit breaker! LOL)

 

Great to see you got it beat!

[Tony D]

As for troubleshooting technique:

You have to identify all components in the circuit where the fuse is blowing. (FSM Wiring Diagram)

 

Then disconnect all components and safe the wires.

 

Install a fuse in the circuit (checks box shorts) and then start reconnecting components one at a time until the fuse blows. Repair whatever you find wrong related to that component, and then continue with a new fuse in the circuit until all parts are reconnected. (I have seen more than one short in a circuit, never never never put everything back together after you found the first short! ALWAYS follow the procedure until the whole circuit is reconnected!!!)

 

I of course learned of this technique AFTER my failure as well...

[Lazeum]

Thanks Tony for the comments

 

It feels good to have this issue sorted. I've learned in the process how to root cause an issue such as this one. It would be good for others to know the tricks instead of shot gunning the problem.

 

I've been running the Z this weekend, I'm still anxious to turn on the lights but it has worked like a charm. It better does since I'll be driving the Z at night next weekend.