Piston Slap: Occam’s Razor Cuts Hardbody Headlight Headaches?

 

My bad. (photo courtesy: imgflip.com)

Robin writes:

Hi Sajeev,

It's me again, steady reader, random poster/questioner, with another D21 question. My good old '94 Nissan D21 is soldiering on, 213,000 and steady on. Of course I don't ever thrash it which I'm sure makes a difference.

But to get to the point: the other day I went out to go to work and presto! No low beams. High beams, check. All signals, markers and brake lights, check. Just no low beams.

Forum surfing ensued, all seemed to point to the switch stalk. I checked fuses. No headlamp fuse? WTF!

What the… (photo courtesy: OP)

I'm hoping against hope that it's something simple and stupid that I've overlooked in my attempts to shoot the trouble. And that another Piston Slap reader has a tip.

Because Piston Slap is only run twice a week, Robin beats us to the punch:

Hi Sajeev,

I emailed you not too long ago about my D21's low beams going out all at one time. Replaced the switch stalk (a common culprit per several forum threads I browsed), scratched my head furiously over the fuse panel, girded my loins for the big $ hit of having someone with a clue troubleshoot the electrics. In the meanwhile, I drove around with my high beams on, undoubtedly pissing off my fellow North Texans.

So this morning I decided to just replace both sealed beams. At worst I'd still be in the same boat but new bulbs. Voila! It was the ultra-rare concurrent low beams burnout phenomenon.

Old Bill from Occam really knew his stuff.

Sajeev answers:

I'm glad to hear you fixed it. Perhaps you also needed that new headlight switch, as it sounds like a multifunctioning switch which are known to misbehave in the oddest ways after 10+ years. Anyone with even a passing interest in Nissan Hardbodies should download this PDF. Yes, it's for a 1990, but it's a start.

I looked at page EL-41 and saw nothing fishy about Hardbody headlights: fuses, connectors, grounds, etc as expected. I am stumped as to why your 1994 fuse box doesn't list a fuse a la the 1990 shop manual. While I think Occam's Razor applies to the 15A fuses (if you have them!), having both headlights blow out simultaneously is odd but the obvious problem after that. Why?

Bonus! A Piston Slap Nugget of Wisdom: 

Because headlights are a wear item. I've said this multiple times before, if your halogen bulbs are 5+ years old and the filament's shiny finish isn't chrome-like (it's tungsten, but you catch my drift) in perfection, they probably need replacement. Hell, I've seen a certified pre-owned, two-year-old used car (presumably with thousands of night miles under its belt) need new bulbs so the new owner can see safely at night.

Send your queries to sajeev@thetruthaboutcars.com. Spare no details and ask for a speedy resolution if you're in a hurry…but be realistic, and use your make/model specific forums instead of TTAC for more timely advice.

The post Piston Slap: Occam's Razor Cuts Hardbody Headlight Headaches? appeared first on The Truth About Cars.

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