Datsun 260Z Headlights

[porkbun]

I hate to ask this question since its been asked so many times before, but I tried the other solutions and they did not work. When I bought the car, both the low and high beams worked fine. The day I got it home, the left headlight had gone out and a few days later the right headlight followed. The amp meter needle bounces when I switch on the low beams (parking lights) but no longer does anything between the low and high beam settings. Literally every other light in the car works except for the headlights. I did some searching and other people who had the same problem as me either found a broken connection under the steering wheel or had a bad switch, so I cleaned the switch, checked all the connections under the steering column and I couldnt spot any problems. This connector was too hot to handle after I tested all the lights and left the lights on the high beam setting for a while(pulled it apart as much as my fingers could handle before taking the picture:

According to the FSM it connects a ton of stuff, but after pulling it apart, I did not notice anything odd with the individual connections and everything looked very clean. After putting everything back together, the plug no longer heats up, but still no headlights. Did my headlights just die out? Is there something I overlooked? Here is the album that has all the pictures of my car and the pictures from around the steering column:

https://picasaweb.google.com/flyingaero/Datsun260Z

I purchased these lights from eBay to replace the old ones, but I would like to see if I can solve the headlight problem before putting in higher power lights and a headlight relay harness. Any idea how I would get the halos to work? The knowledge of electronics I had does not translate to inside the car like I thought it would

Edited September 2, 2012 by porkbun

[EScanlon]

Although it's obvious, it can get overlooked... have you checked your fuses? Don't just look at them, those glass fuses have been known to be bad even though they appear good. Remove them and do a continuity check on them. While you're at it, check to make sure you have 12v across their terminals when the headlights are on.

FWIW

E

[5thhorsemann]

The best way to test fuses is to check both sides to ground, a good fuse will show the same value to ground on both sides of the fuse, then check the voltage across the fuse, it should be 0.0 volts. If you are reading ANY voltage across the fuse, you are seeing a voltage drop and this tells you the fuse is bad. Continuity tests only work for a blown fuse or breaker, not one that is otherwise defective.

[Zed Head]

Headlights do get old and die. If you have power at the fuse (measure voltage from the fuse to ground), there's probably power to the headlight.

I bought a bunch of new fuses and just replaced all of mine. Cheap insurance. I found one that looked original, probably been in use since 1976. Maybe 35 years old. Most of the others looked pretty crusty on the inside.

Your ammeter won't bounce between high and low until the headlights work again. No current (amps) is flowing.

The connector probably had a poor connection causing resistance that caused heat. When you opened it up and put it back together you created a better connection so the heat went away. When cars sit without moving, the heating and cooling cycles are enough to open up the connections and allow light corrosion to fill in. Use 'em or lose 'em.

[EScanlon]

I'll differ on the fuse evaluation method.

Time and time again, people have posted that they've checked the voltage across the fuse, to ground from either terminal and ... it ends up being the fuse that was bad.

It's simple and it works, take the fuse out of the fuse box and check continuity through it. If it checks out, then the simple act of removing and replacing it may be enough to, as it apparently already happened, to make a new and better connection.

FWIW

E

[5thhorsemann]

I agree E, but if there is a bad connection at the fuse block you will see that too if you use the voltage meter across the fuse (testing with the probes on the tabs, not the fuse itself) you will read a voltage drop caused by the resistance of the bad connection. A continuity test uses a very low voltage and almost no current to determin if there is a complete circuit. The voltage meter method gives you real world readings with the circuit under load. Arching at the fuseblock/ fuse connection due to a loose fuse holder in combo with a problem in the protected circuit often can cause the kind of problem that gets missed, and you will just keep fiddeling around with the fuses untill the real problem comes to a head and leaves you on the side of the road. By testing the system undisturbed you can find all the problem areas at one time (usually)

[EScanlon]

I'm not arguing the reliability nor the extent to the type of diagnosis that a multimeter provides.

The Average Joe simply uses his multimeter for the most basic of purposes... what's the voltage on AC or DC; Resistance and Continuity.

What each of those values indicate is more often than not, only useable by those that work in the electronics industry. Granted it doesn't take an EE degree to see 12V DC or 120AC or 3 Ω or to hear the "beep" of cotinuity, but to determine that 10.3 Ω means that .... and there is where it gets technical.

An obvious bad connection at the fuse box is like any other bad connection... loose or broken off wire... probably NOT what you want happening. But measuring voltage that is going through the fuse, well I'm no genius with the multimeter, but wouldn't it be reading the voltage from negative to positive terminals of the fuse and therefore read 12V? Additionally, one side of the fuse would read 12V and the other should read 0.0V.

Again, what I'm saying is that your knowledge and experience may be that YOU can discern much more than the Average Joe but he uses it like an LED current tester... if it's on there's current, if not... no current.

The R&R of the fuse is bone simple and most everyone can do it.

FWIW

E

[Wade Nelson]

Headlights are fairly easy and quick to diagnose after you've done a few. The #1 failure is the GROUNDING wire for BOTH headlights comes loose from the body. Both bulbs go out. If a single headlight fails, MOST OFTEN it's a burned out bulb. One followed by the other typically means something more complex.

So you turn on your headlights (ignition on), because SOME cars headlights don't stay on when the ignition is off, and I can never remember WHICH the Z does...and pull the connector off a single headlight.

See if you've got battery voltage (12.2-12.8) on one of the pins, and ground on the other. Flip it to high beams and check again.

You can use a test light to check for voltage AND ground, putting the end of the lead first on the battery negative, and then positive terminal. No meter needed!

Next, what I should have checked FIRST, would be the fuse for the headlights.

If your connector is getting hot your switch is pulling WAY too many amps, and you should IMMEDIATELY install headlight relays. Unless, of course, you like replacing $159 headlight switches (Rock Auto still has 'em)

The connector getting hot is a vital clue --- if the connector is hot, but the bulbs are not lighting up, you PROBABLY have a dead short to ground somewhere in the headlight harness. You can unwrap the entire harness to find it, or just wire around it (including your new relay pack) and save a whole bunch of time.

If you add relays, your headlamps will be noticeably brighter, provided you use the correct gauge of wire. The voltage DROP in a headlamp switch means, if your battery is at 12.6, you're lucky if you're getting 12.3 at the bulb connector in a 30 year old car. That .3v voltage DROP means a significant reduction in brightness --- like 30% or more.

Which is why I always wire headlamps and associated relays with 10 or at most 12 gauge, and NEVER the 14 gauge mfr's do. (Even the aftermarket headlight sockets/pigtails today come with 14 AWG wires!!!! ) I like my headlights bright white, not yellow. Beefy wiring and new bulbs and even an OLD car, with an alternator putting out 13.5+ volts can LIGHT UP THE NIGHT.

Hope this helps!

[porkbun]

Turns out that one of my replacement fuses was a bad one. The right headlight just needed a fuse, the left needed a new bulb. I threw the ones I got off of eBay in and after hours of messing with the assemblies, I got everything back together and in place.

I threw them in there before the harness for emergency situations where I have to drive when it starts getting darker. I forgot to mention that only my high beams are working, but I havent searched for a solution for that yet. I take it the MSA headlight harness wont work at all in my 74 260?

[porkbun]

Does this count as hijacking my own thread?

I left for a short trip yesterday and decided to test the rear window defogger on the way there. Not only did I lose a hubcap, but I forgot to turn the defogger off when I turned the car off. Had to get the car jumped to get going and went straight to a car parts store where they told me to go to a gas station to get my battery charged and that my alternator would need to be changed soon (after testing both). Would I run into any problems if I went with an OEM voltage regulator and this alternator: http://www.autozone.com/autozone/parts/Duralast-Import-Alternator/1974-Nissan-Datsun-260Z/_/N-iopilZ9ci9i?itemIdentifier=334268_29983_10563_ ?

[EScanlon]

Your defrost switch should not have drained your battery, unless it's hooked up to the wrong power source (i.e. non-switched instead of switched).

As far as the Reg/Alt swap, I'll leave to others, but I don't know why you would run into problems.

Just make sure that the alternator is NOT internally regulated and that your car DOES have the provision for a voltage regulator in the engine bay.

If either of these is true, then you need to adjust what you're getting.

An internally regulated alternator does not need an external regulator (duh! sorry couldn't resist), BUT you do have to shunt a wire in order for it to work with your car, if your car has the wiring for the voltage regulator.

If you don't have the wiring and it is an int. reg. alternator, then you don't need the external regulator

On the other hand, if it is NOT an internally regulated alternator and your car requires one, then you need a different alternator and you can forget the external regulator.

Got that? I wrote it and I'm still thinking it through.

E

[porkbun]

Your defrost switch should not have drained your battery, unless it's hooked up to the wrong power source (i.e. non-switched instead of switched).

I think its the defrost switch because the car has never had problem with sitting before and everything was turned off except for that switch. It very well could be some funky wiring since it does have an 8 track player behind the passenger and theres a mess of wires under the mats. I was just wondering about the alternator and regulator to see if there was a preferred replacement, and to see if there was a more modern replacement, but now that I think about it, an internally regulated alternator is the modern replacement. Ill be ordering that Duralast and the OEM regulator if no one says anything by Monday