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Headlights won’t turn on


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So I was going to drive my 1978 620 into town to get gas tonight, and I went to start my truck and it wouldn’t crank. I tried to headlights to see if I had battery power, and they didn’t come on. I disconnected the positive lead from my battery for a while, then reconnected it. My truck then was able to crank, but my headlights won’t come on. I already checked the fuses in the cab, and they’re all good. I also removed the headlamp fuse and put it back in to see if the contacts were dirty, but it didn’t help. The PO rewired part of the headlight circuit. There is a pullout switch to turn them on and off, and a click button type switch by my feet for the brights. I can add pictures if that doesn’t make sense.

 

I’m not really sure where to begin diagnosing. Any info is appreciated

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This.

 

Clean and tighten BOTH cables and battery posts. If stripped bolts, replace.

 

 

Practically impossible to troubleshoot lights that have been messed with. There's just no telling what some incompetent, though well meaning idiot may have done to it.

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make I simple ck for Power using a test light.

Make sure light works by touching the 12volt on Battery then work your way up to the fuse box. . Lights should come on. Put a new fuse in as a old one may look good in the galss but the ends are broke inside

 

If it worked before then its just a connection issue most likely. Even if a hack wire job.

 

Last power proplem I had was a broken bolt n battery cable. I would get a 1 start then battery would look weak. I bought cables and battery when I took it apart said Fuck maybe that's all it was .

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Put a new fuse in as a old one may look good in the galss but the ends are broke inside

 

If it worked before then its just a connection issue most likely. Even if a hack wire job.

I just took the switch out and This is the problem. The fuse that’s on the switch itself looks good, but is actually broken. I’m heading in to grab a new one and will check back when done! Thank you all

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I just took the switch out and This is the problem. The fuse that’s on the switch itself looks good, but is actually broken. I’m heading in to grab a new one and will check back when done! Thank you all

 

Can't be a Datsun switch. Hard to trouble shoot home made fixes. Like a doorbell switch on the steering column for the horn. Or a light switch on the dash for the headlights

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I’m having more problems with my headlights again. The headlight switch gets very hot when the lights are on. I haven’t been using them because I don’t want to start a fire. I’ve been trying to figure it out myself before asking for help, but I haven’t been able to fix it. I’ve checked the switch connections for clean contacts and they’re all good, I’ve removed the electrical “plugs” from the back of the fuse box to make sure they’re clean, I’ve checked around for high resistance, I just can’t figure it out. Any ideas? This is not stock wiring by the way. I can try to get pictures of the wiring if that would help. Thanks in advance 

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On 4/28/2018 at 6:47 PM, Speedymaru said:

Yes, it is not a Datsun switch. The previous owner wired something up just before i bought it. Thank you all for the help

 

Who knows what this switch is rated for? 55 watt dual low beams draw about 9 amps. A house light switch and 60 watt bulb is 0.5 amps.

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They are not stupid questions.  Unfortunately there is no easy answer. A previous owner butchered the wiring and probably added several problems on the way. You are in the PNW alive with old Datsuns. Try to find another wiring harness?

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Sorry for the late reply, been pretty busy. That would be the correct thing to do, but I’m afraid it might be out of my expertise. I would like to try to locate the source of the problem. They’ve worked before so I’m thinking they’ll work again. I may end up taking it to a shop to have them take a look. I’m not well versed in wiring. Thanks for the help 

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clean connections.

a shop might just rig it up to work .

I would buy a h4 harness. I would get it to work and just use the old light system to trigger the H4 harness so you wounldnt draw alot of current on the stock light circut. the H4 harness would then be powered by a relay from the battery.

 

somebody near by could maybe help you.

 

key is get it back to stock then add the harness

key is knowing what the previos owner did first

Edited by banzai510(hainz)
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Read up on it. you unplug your pass side outside lamp,it has a 3 prong plug.

this 3 prong will now be your trigger input to a new H4 harness . The new harness has 2 relays one for the lows and 1 for HIGHS of the outer lamps. and Power.

Your stock lamps and H4 lamps have 2 elements on there.

 

the Inner HIGH lamps will not be touched and hopefully will still work.

 

 

there H4 harness are about 25 -40$ for the cheaper Chinese better ones run upward.

 

I got mine from a place called 4 crawlers or soemthing like that show installed on a Toyota 4x4 pickup

 

Just remember Im trouble shooting from afar. so hard to tell what you have. but Im postive your fuses in fuse box will not melt anymore

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