ignition on = lights off ??? (76 fj40)

[iliketomakestuff]

Hang with me on this explanation.

[ignition off]
Lights turn on and off fine

[ignition ON]
running lights turn on, but headlights do not

[lights switched ON, ignition ON/running]
turn key to off position.. truck does NOT shut off, until I turn off the lights

😵‍💫

I've been fixing and replacing lots of electrical stuff lately, but have not touched the switch for the lights.. thinking it might be the culprit, but does anyone have any idea where to start for tracking this down? This one has me stumped as to where to even start.

 

[B y r o n]

What items have you been working on? Fuse panel? Heater, lights (side marker, etc.)? Alternator, battery?

 

[iliketomakestuff]

Most recently I replaced voltage regulator and ignition switch , replaced a point to point wire to overcome a short between the voltage reg and alternator

 

[Mr. Green]

Are headlights on while truck is running with ignition ON position? If not, Appears it’s repathing via headlight circuit for your kill. Pull headlight fuse and redo test. I don’t know 76 ignition Wiring circuit but can’t imagine too far different from 74. Suspect something in new ignition. Compare old to new to confirm.

 

[GA Architect]

Not sure if you have these or not, but if you can find the '76 version, it may be of some significant help.

 

[B y r o n]

Most recently I replaced voltage regulator and ignition switch , replaced a point to point wire to overcome a short between the voltage reg and alternator

Ignition switch - Was it a Toyota OEM part or a aftermarket replacement? I've seen threads where aftermarket parts have had wires in the wrong pin location and caused issues.

Point to point wire - Is it possible that there was a diode in the wire that didn't get replaced? Not Toyota alternator but I had an issue with Chevy alternator that was back feeding power to the coil and engine would not shut off. I added a diode and problem solved. Maybe is was a resistance wire that simply didn't allow enough voltage to fire coil but your replacement does. Just a guess on this last one.

 

[ToyotaMatt]

- your headlamp switch & Electrical key switch primary large gauge wires have been tapped into at one point for other uses

- or

- your ignition ROTORY switch has failed and melted down internally .......

- or

- the BATT B+ white wire w/ blue tracer stripe from key switch feeds the other 3 wires , blue w / red tracer , black w/ White tracer , black w/ yellow tracer

- remove your pos. battery B+ cable first !

- then remove the 2 10mm hex bolts holding on fuse box , flip it over and carfully inspect all the connector plugs feeding fuse box , a melt down here WILL cause all your symptoms , and does indeed occur for many reasons age and time included ...

 

[iliketomakestuff]

first test, I unplugged each light individually, and it behaves as it should, but if I plug them both in it does the weirdness described above.
When I remove the headlight fuse, it behave as it should.

 

[ToyotaMatt]

first test, I unplugged each light individually, and it behaves as it should, but if I plug them both in it does the weirdness described above.
When I remove the headlight fuse, it behave as it should.

" when you remove the head light fuse it behaves as it should ? "

please elaborate on this key point , because if i read it right , then your mooching B+ from another yet to be identified source and this is a huge RED FLAD ⛳issue

 

[iliketomakestuff]

" when you remove the head light fuse it behaves as it should ? "

please elaborate on this key point , because if i read it right , then your mooching B+ from another yet to be identified source and this is a huge RED FLAD ⛳issue

Sorry. I meant that the ignition on/off acts as it should. The lights do not turn on when the fuse is out

 

[ToyotaMatt]

Sorry. I meant that the ignition on/off acts as it should. The lights do not turn on when the fuse is out

ok