Headlight always on, charging issues tercel 86

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Esaus
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Joined: Sun Oct 16, 2022 11:12 am
My tercel:: 86 Tercel 1.5 Europe

Headlight always on, charging issues tercel 86

Post by Esaus »

Hi! Im a swedish recent tercel 1986 owner where I purchaced a car that had been sitting for 10 years. its in rough shape and needs alot of fixing. I'm having a wierd issue with charging and heatlights. The issue is that the headlights stay on constanly when the charging fuse is put in the fusebox. Even if i turn the lightswitch to parking lights or off the headlights still are on. Alternator and voltage regulator has been replaced. Issue persists.

backstory:
When i got the car it wouldn't charge the battery and the battery light was on. i saw that the fuse was removed so i put it back in and the headlight and parking lights would immedietly turn on with the car off. Both in the front and rear. When removing the fuse the relay would click and the lights would turn off.

At first I thought it was a short of some kind so I looked inside the fuse box and couldnt see any immidiate issue. I tried checking whatever I could think of and replaced the voltage regulator as I thought it was faulty. It didnt do anything and the issue persisted. I continued looking at wiring and checked connections. When removing the voltage regulator the lights would turn off! I opened up the wiring harness going inside the front left fender and couldnt see any issues there either.

I googled around and saw that the charging and brake light combo would point at the alternator. I took the alternator apart and saw that it had burnt diodes but the ground to the case and the stator i think its called was functioning. I ordered a new alternator without the internal voltage regulator as i had the external one. I installed it today and the issue still persists. I have also replaced the battery since the old one was faulty and had 14 volts without the car on. The alternator wont charge the battery it seems despite the new alternator. I think i checked continuity on the wires from the alternator to the voltage regulator during the initial troubleshooting and they were fine.

Any guesses what it might be? all i can think of is that the voltage regulator is faulty even though i replaced it. Might it still be a short? anyone with experience with this? I have the tercel workshop manual but cant really figure it out.
1986 Tercel 4WD, Red, 170000km, restored.
1987 Toyota Corolla Dlx hatchback, 250000km
1988 Toyota Corolla touring 4wd, estate yet to be restored
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NWMO
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Re: Headlight always on, charging issues tercel 86

Post by NWMO »

Esaus,

Did you find an alternator that used the same plug? or did you have to modify the wires. You should be able to check the alternator when running and get 14+ volts on the rear power connection point. If so, you may need to check the voltage regulator. It’s been many years since I worked with an externally controlled alternator, but I seem to recall a need to “polarize” the regulator? or some other component?

As for your light situation, it sounds like the headlight switch has failed “on” or more likely, someone has monkeyed with the wiring.

Chris
Psalm 37:4 "Delight yourself in the Lord and he will give you the desires of your heart"

In remembrance of my friend ARCHINSTL:

T4WD augury?
"Oh, do not ask, 'What is it?' Let us go and make our visit."
T.S. Eliot - "The Love Song of J. Alfred Prufrock"

"Now and then we had a hope that, if we lived and were good, God would permit us to be pirates."
Mark Twain
Esaus
Advanced Member
Posts: 59
Joined: Sun Oct 16, 2022 11:12 am
My tercel:: 86 Tercel 1.5 Europe

Re: Headlight always on, charging issues tercel 86

Post by Esaus »

Hi! It has the same plug as the original one. I made sure to order the correct one alternator. It is a reman one. I'm not getting a charge currently with the new alternator as when i enter the charge fuse the headlights turn on. I'm guessing there is a short somewhere. The headlighs work normally when the carge fuse isnt in the car. I can change between the different settings no problem with the stalk but when i insert the charge fuse the switch wont work and the light are always on.

I havent had time to check for faults in the electrical system. I have been busy with replacing drive shafts, balljoints, brake booster and gaskets etc.
1986 Tercel 4WD, Red, 170000km, restored.
1987 Toyota Corolla Dlx hatchback, 250000km
1988 Toyota Corolla touring 4wd, estate yet to be restored
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NWMO
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Posts: 1615
Joined: Wed May 20, 2015 1:08 pm

Re: Headlight always on, charging issues tercel 86

Post by NWMO »

Wiring is the next thing to check for your headlight issue. Good luck and let us know what you find.

Chris
Psalm 37:4 "Delight yourself in the Lord and he will give you the desires of your heart"

In remembrance of my friend ARCHINSTL:

T4WD augury?
"Oh, do not ask, 'What is it?' Let us go and make our visit."
T.S. Eliot - "The Love Song of J. Alfred Prufrock"

"Now and then we had a hope that, if we lived and were good, God would permit us to be pirates."
Mark Twain
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Nordical25
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My tercel:: 2 4wd 1987's. One with 4a, other with 3a
Location: Finland

Re: Headlight always on, charging issues tercel 86

Post by Nordical25 »

Yes, let's hope that you will find a source for that. Do you have an original car manual? That explains which fuses you need for headlights. It sounds like a wiring error. Please tell if you lack manual. I can scan some fuse information to you on Euro Tercels if needed.
Esaus
Advanced Member
Posts: 59
Joined: Sun Oct 16, 2022 11:12 am
My tercel:: 86 Tercel 1.5 Europe

Re: Headlight always on, charging issues tercel 86

Post by Esaus »

I managed to fix the issue. I noticed a small burnt smell around the battery/ charging regulator and decided to try the old regulator again. It fixed the issue! Seems the new regulator with integrated circuits had burnt up. Perhaps with the overcharging situation before i replaced the alternator. Either way the new part had failed. It now works again and the headlights work as normal now. Might have shorted internally or something.
1986 Tercel 4WD, Red, 170000km, restored.
1987 Toyota Corolla Dlx hatchback, 250000km
1988 Toyota Corolla touring 4wd, estate yet to be restored
User avatar
NWMO
Highest Ranking Member
Posts: 1615
Joined: Wed May 20, 2015 1:08 pm

Re: Headlight always on, charging issues tercel 86

Post by NWMO »

Good job!
Psalm 37:4 "Delight yourself in the Lord and he will give you the desires of your heart"

In remembrance of my friend ARCHINSTL:

T4WD augury?
"Oh, do not ask, 'What is it?' Let us go and make our visit."
T.S. Eliot - "The Love Song of J. Alfred Prufrock"

"Now and then we had a hope that, if we lived and were good, God would permit us to be pirates."
Mark Twain
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