late 80 upper rear hatch electrical questions (and leaving it open)?

[lumbee1]

I don't know about your problem with the headlights and hatch, but I would suggest running DC wiring for a third dome light. It's a common mod for the hatch. Wiring attaches to the 2nd row dome light. I don't have a good picture but hopefully this helps.

In addition, I push a carabiner in the lock mechanism to shut off the door lights and dome lights but keep the hatch open. To release the carabiner just pull the interior hatch release handle.

 

[NeverFinis]

do you mind if i ask you for some explanations on how i should start tracking things here? i realized this is time on your end so its not a big deal if it doesn't happen i just try to learn a little bit.
for instance greening think is some kind of open closed switch (or closed open i guess) at the tailgate? anyway is it possible for you to help me start seeing how this circuit (if that's the right word) is functioning? i see the bulbs obviously. and i think there are some diodes in here for some reason i dont totally understand.
but also i always have an issue understanding - well i guess when a switch is normally open a circuit is not energized? so when the hatch closes it gets energized? and my clue here is that the hatch in green here shows open so i should know that closing the hatch closes the circuit?
then everything "upstream" in the sense it is on the same line (or on a line that intersects in a dot) - well it gets energized - well when sort of implicitly it would not be energized otherwise? or i guess a line in a circuit can be energized even if it interstate at with this "normally open" hatch circuit?
sorry it's always a kind of practical learning exercise over here when i work on the 80....

View attachment 4010064

Yes, the green is the switch in the upper hatch door. Toyota shows switches in its normal state. In this case, the switch is open because the hatch is normally closed. If you open the hatch, the switch then closes, allowing current to flow.

Diodes, in most situations, allows flow of current in one direction.

There is voltage (relative to ground, ⏚) on one side of the switch and there is ground (⏚) on the other side.

In the above circuit, current can not flow unless the switch is closed (hatch is open). It is current that allows work to be done, like lighting a bulb.

 

[Irish Reiver]

@Irish Reiver and @landcruiser3DP

1. Does this behavior persist if you pull the Dome Bulbs?
2. Does this behavior persist if you pull the Dome Fuse?

Behavior = Headlights turned off by Auto Off, Open rear hatch, Headlights then turn on.

When my headliner was out, I noticed Toyota routed the 2nd row seat dome light wiring wedged into a metal bracket attached to moonroof tray. It was a very likely place to develop a short.

Just did some testing on my '96.
The short version is the headlights will come on every time I open the hatch BUT when I remove the rear dome bulb the issue is completely gone.

My dome lamps are all incandescent. I also noticed that when I open a rear door the lamp is bright but opening the hatch only the lamp is dim.
I still don't have a high level brake light (might be dim but can't be sure at the moment) and my rear windscreen wiper results in a steady clicking - with the cadence of a turn signal).
Time to chase some grounds...

 

[Irish Reiver]

Quick update : - Just pulled the center console. The ground for some (if not all the circuits in the rear hatch) are located here. It all looked nice and clean with no oxidization but I gave it a freshen up with some sand paper. It worked a treat and now I have high level brake light and the rear wiper working again.

It made no difference to the headlights / hatch scenario

 

[landcruiser3DP]

I am having difficulty parsing what you are writing.

1. Pulling the rear dome bulb did or did not stop the behavior?
2. Pulling the dome fuse did or did not stop the behavior?
3. Replacing the one LED bulb with an original incandescent bullb did or did not stop the behavior?

Answer yes or no to each question.

Where are you located? I saw Woburn Toyota as a place you might order from. If you are in Mass, it might be easier if I come by.

just finishing up at o'riellys here. i will try to be concise but if i miss anything please let me know. i am interested in learning here obviously in addition to fixing this. also trying to be a good student.

background:
i had a LED in the front dome light (behind front seats) and an incandescent in the rear dome light in the back. i had an LED in the back but it was too bright for camping so i put then incandescent back in.

i also see i had two LED's for the licence plate (one was flashing on and off) and i see i had two LEDs in the drivers and passenger side vanity lights in the visors (drivers side was out).

1. Pulling the rear dome bulb did or did not stop the behavior?

yes but pulling the FRONT dome light fixed the drivers door not turning off the headlights issue. it did not fix the rear hatch turning the lights on issue.

so pulling the front dome light caused the automatic headlight off when keys are pulled and drivers door is opened to work. this was an LED. i just took out the LED and it works.

2. Pulling the dome fuse did or did not stop the behavior?

did not try this. i will test this if it is of use here.

3. Replacing the one LED bulb with an original incandescent bullb did or did not stop the behavior?

yes. pulling the front LED dome light fixed the drivers side door issue without putting an incandescent in its place. putting an incandescent bulb into the front and rear dome light when there were no bulbs in either dome light subsequently ALSO fixed the rear hatch issue.

elaborating: i pulled the rear incandescent dome light after pulling the front LED fixed the drivers side door issue but did not fix the rear hatch opening causing front headlights and or front and rear taillights going on.

this did not fix the latter issue.

i just bought two incandescent (even though i had one in the rear dome light) and put one new incandescent in each of the dime lights.

opening the drivers side door still causes the headlights to go off and now opening the rear hatch does not cause the headlights to go on.

i think this means putting a bulb into the rear dome light fixed this issue since i tested like three times with both bulbs out. this seems weird but i tested both issues three times here with incandescent bulbs on the two dome lights and i don't have either problem now.

i how that makes sense. i'd like to be able to "see this" in the electrical diagram not not mission critical!

one other item is the vanity lights in the visors are LED. one didn't work and i think i managed
to short out the other one (?) because i used a key to try to pull it and making contact (?) either blew a fuse or shorted the LED i guess?

 

[landcruiser3DP]

Quick update : - Just pulled the center console. The ground for some (if not all the circuits in the rear hatch) are located here. It all looked nice and clean with no oxidization but I gave it a freshen up with some sand paper. It worked a treat and now I have high level brake light and the rear wiper working again.

It made no difference to the headlights / hatch scenario

wow. great news. do you have LEDs in the two dome lights?

 

[NeverFinis]

Edited: Ignore this if you have solved the issue.

After looking at the wiring diagrams, I think one should inspect connectors BU1, BV1, BW2. (Going by LX450 1996 EWD naming).

The first two are in the left quarter panel. Look at these first. I do know that the wires on BU1 are very tight and close together. I had damage on BU1 from a rodent.

The last one, BW2, is in the hatch.

You may have a short from one wire to another, not necessarily to ground. I put the pin numbers that one should look at first. If you don't see obvious damage, then proceed to probing for voltage, continuity, and continuity to ground.

BU1: Pins 3, 4

BV1: Pins 1, 4, 8

BW2: Pins 2, 3

 

[NeverFinis]

Quick update : - Just pulled the center console. The ground for some (if not all the circuits in the rear hatch) are located here. It all looked nice and clean with no oxidization but I gave it a freshen up with some sand paper. It worked a treat and now I have high level brake light and the rear wiper working again.

It made no difference to the headlights / hatch scenario

Nice. There are a ton of circuits that ground there. I would have expected much more issues if there was a ground issue there.

 

[NeverFinis]

just finishing up at o'riellys here. i will try to be concise but if i miss anything please let me know. i am interested in learning here obviously in addition to fixing this. also trying to be a good student.

background:
i had a LED in the front dome light (behind front seats) and an incandescent in the rear dome light in the back. i had an LED in the back but it was too bright for camping so i put then incandescent back in.

i also see i had two LED's for the licence plate (one was flashing on and off) and i see i had two LEDs in the drivers and passenger side vanity lights in the visors (drivers side was out).

1. Pulling the rear dome bulb did or did not stop the behavior?

yes but pulling the FRONT dome light fixed the drivers door not turning off the headlights issue. it did not fix the rear hatch turning the lights on issue.

so pulling the front dome light caused the automatic headlight off when keys are pulled and drivers door is opened to work. this was an LED. i just took out the LED and it works.

2. Pulling the dome fuse did or did not stop the behavior?

did not try this. i will test this if it is of use here.

3. Replacing the one LED bulb with an original incandescent bullb did or did not stop the behavior?

yes. pulling the front LED dome light fixed the drivers side door issue without putting an incandescent in its place. putting an incandescent bulb into the front and rear dome light when there were no bulbs in either dome light subsequently ALSO fixed the rear hatch issue.

elaborating: i pulled the rear incandescent dome light after pulling the front LED fixed the drivers side door issue but did not fix the rear hatch opening causing front headlights and or front and rear taillights going on.

this did not fix the latter issue.

i just bought two incandescent (even though i had one in the rear dome light) and put one new incandescent in each of the dime lights.

opening the drivers side door still causes the headlights to go off and now opening the rear hatch does not cause the headlights to go on.

i think this means putting a bulb into the rear dome light fixed this issue since i tested like three times with both bulbs out. this seems weird but i tested both issues three times here with incandescent bulbs on the two dome lights and i don't have either problem now.

i how that makes sense. i'd like to be able to "see this" in the electrical diagram not not mission critical!

one other item is the vanity lights in the visors are LED. one didn't work and i think i managed
to short out the other one (?) because i used a key to try to pull it and making contact (?) either blew a fuse or shorted the LED i guess?

I think from what you have written...everything is good due going back to incandescent.

Yes, you probably shorted the led.

I personally have LEDs in all the doors, but not the Dome lights. They are still incandescent. My dash is all LED, except for the low fuel warning light.

 

[landcruiser3DP]

I think from what you have written...everything is good due going back to incandescent.

Yes, you probably shorted the led.

I personally have LEDs in all the doors, but not the Dome lights. They are still incandescent. My dash is all LED, except for the low fuel warning light.

crazy. but kind of stoked to see this working. they are so kind of variable it is hard to even understand how they are supposed to work to even get to troubleshooting (at least for me).
are you able to help me - well how do i get from this circuit to the headlights going on?
there is a different diagram that also tied to the switch other rear hatch which is tied to the tail lights and head lights?

 

[NeverFinis]

are you able to help me - well how do i get from this circuit to the headlights going on?

Can you rewrite so I can understand?

there is a different diagram that also tied to the switch other rear hatch which is tied to the tail lights and head lights?

No common circuity other than shared grounds and common power.

My theory, there wasn't enough of a voltage drop from the LEDs compared to the incandescent bulbs. That excess voltage, post LED, was able to back feed other circuits due to sharing a common but poor ground.

 

[landcruiser3DP]

Can you rewrite so I can understand?



No common circuity other than shared grounds and common power.

My theory, there wasn't enough of a voltage drop from the LEDs compared to the incandescent bulbs. That excess voltage, post LED, was able to back feed other circuits due to sharing a common but poor ground.

ok. thanks a TON for this. i pretty much basically want to just sit here like a simpleton turning the ignition key on, pulling it out, opening the drivers side door and watching the light go out over and over. then getting out once in awhile and opening the hatch and not seeing exterior lights going on.
but help/humor me here please?
the switch at the tail gate is NO or normally open? so when i OPEN the hatch this circuit is "closed" by the switch and this energizes a lot of this circuitry (shown in heavy RED)?
meaning it energizes this front and rear dome light and - well we are saying that there is something about the low load of the LED in the front dome light that caused the two dome lights to send more current than normal out all of these thin red arrows (and the heavy red line) and this somehow activated headlights and/or tail lights?

 

[NeverFinis]

the switch at the tail gate is NO or normally open? so when i OPEN the hatch this circuit is "closed" by the switch and this energizes a lot of this circuitry (shown in heavy RED)?

Yes. As shown by the manual, it is normally open. The switch closes when the hatch opens. It connects the circuit to ground, allowing current to flow.

The circuit before the switch is always "Energized" (12V) but current can't flow to ground until the switch closes.

meaning it energizes this front and rear dome light and - well we are saying that there is something about the low load of the LED in the front dome light that caused the two dome lights to send more current than normal out all of these thin red arrows (and the heavy red line) and this somehow activated headlights and/or tail lights?

I don't know about more current, but higher voltage since voltage drop across a led is less than an incandescent. Couple it to a bad ground, and now you have higher voltage throughout the circuit.

 

[landcruiser3DP]

Yes. As shown by the manual, it is normally open. The switch closes when the hatch opens. It connects the circuit to ground, allowing current to flow.

The circuit before the switch is always "Energized" (12V) but current can't flow to ground until the switch closes.


I don't know about more current, but higher voltage since voltage drop across a led is less than an incandescent. Couple it to a bad ground, and now you have higher voltage throughout the circuit.

i see. can i ask you to help me with the terms here? if the current before the switch is energized - well what does that mean as compared to whatever i call the circuit when it closes so it can go to ground?
is that a good question?
like it's energized but doesn't have 12V but if i close the circuit by opening the hatch it is - live? powered? or what do i say please?

 

[NeverFinis]

Energized isn't a term I use, except in regards to capacitors.

There is Voltage before the switch, but Current can not flow because the switch is open. Therefor Current = 0, but Voltage >= 12.6V

Voltage is the difference in electrical potential between two points in a circuit.

For example, Voltage between a Battery and Ground in a vehicle would normally be at least 12.6V.

Current is the flow of electric charge through a circuit. Current can not flow if the circuit is open.

Power (watts) = Current x Voltage

 

[smorkington]

Likely moisture / corrosion in the connectors behind the headliner mine we really bad

 

[landcruiser3DP]

Energized isn't a term I use, except in regards to capacitors.

There is Voltage before the switch, but Current can not flow because the switch is open. Therefor Current = 0, but Voltage >= 12.6V

Voltage is the difference in electrical potential between two points in a circuit.

For example, Voltage between a Battery and Ground in a vehicle would normally be at least 12.6V.

Current is the flow of electric charge through a circuit. Current can not flow if the circuit is open.

Power (watts) = Current x Voltage

ok. that's progress. i will reread it.
i have one more and then i am going to try to tackle the rear hatch brake light per comments here. i /super/ appreciate your walking me though this. i can't really do it without help honestly.
one last one. i am almost sure i /shorted/ the vanity mirror using a key to get the LED bulb out since wit went out when i was prying it and made contact.
so presumably next time i need to use wood - or i guess i can hold that little activation switch closed manually while i pry it out i suppose.
i assumed i blew a fuse and i also saw the CLOCK blank when i was driving home. so i figured i had to replace a 10A fuse or something.
/anyway/ tonight i ran out at 8:30PM and saw ehe clock ON showing 1:00 and also the passenger side vanity is working now.
is there any good reason it would be out - meaning the circuit i guess since the battery has always been connected - for basically like 7 hours and 30 minutes?
like is there a good electrical explanation for this? it temporary blew something that eventually recovered? i mean i kind of really don't get this?(!) or is it possible for the LED to short out for 7 hours and keep the clock from working too?(!)

 

[NeverFinis]

No idea but the clock has multiple power sources. Check your cig fuse.

 

[landcruiser3DP]

No idea but the clock has multiple power sources. Check your cig fuse.

View attachment 4010677

thanks. last one promise.
so i call a circuit "open" and "closed" or how do i talk about the circuit relative to the hatch opening and closing the circuit?
you know what i mean? i mean it obviously turns on lights once the hatch opens and the switch closes? totally stoked to get this headlight and rear hatch issue solved. sp thank you. it's hard to even understand how these are supposed to work when then start acringe weird.

 

[landcruiser3DP]

Quick update : - Just pulled the center console. The ground for some (if not all the circuits in the rear hatch) are located here. It all looked nice and clean with no oxidization but I gave it a freshen up with some sand paper. It worked a treat and now I have high level brake light and the rear wiper working again.

It made no difference to the headlights / hatch scenario

so i cleaned this connector to try to tackle the rear upper brake light and it's not lighting up. i think next step is to open up the left rear pillar and find the harness.
also i guess there must be some troubleshooting steps in the FSM?