FJ-80 window operation = brighter lights (1 Viewer)

[jamot]

Picked up a 91 FJ-80 today, pretty nice, 192k, good price, needs basic 80 tlc from po neglect. One strange thing I encountered is when you operate the power windows, and put the window motor under load, the head lights and dash lights brighten..... Let go of the switch, no load, and they dim. I've seen the oposite happen, ie dimming lights under load, but not this ( I don't remember my other 91 doing it at least)... Does anyone know what gives or where to start checking grounds, relays etc?

I did notice the po did some additional underhood wiring for some type of accessory which I have yet to check out, but I'm always suspect of additional wiring possibly not done right. Again this is her first night home, so wondering if anyone else has seen this light phenomenon occur?

 

[RavenTai]

There was a similar thread recently, it was also a Fj-80, no solution posted,

https://forum.ih8mud.com/showthread.php?t=37080


I'll ask you the same thing, with a meter on +/- posts of the battery what is the reading wile rolling down the window?

 

[thorvald]

mine does the same thing, havent checked into it. was thinking its the same as the engine picking up speed to operate air conditioner? picking up speed, making the alternator work harder? would be interested in a reason for it also.

 

[jamot]

Thanks guys.

No time to put a meter on her yet. It'll be another day before work will allow me to spend the time checking some more things out and also finding out what those two non oem wires are coming off the battery. Again always suspicious of other peoples wiring jobs, especially coming off the battery directly.

I'm not sure the extra wiring and light fluctuations are related though. Almost seemed like it was doing it as the windshield wiper motor operated too. I just sold another 91 I had for almost 2 years and never noticed such. Again strange, but I'm intrigued to the point I'll have to figure it out.

The past has taught me the "bad connection gremlin" ie grounds, battery connection etc, could play a role. Anyway if no one can nail it, I'll update in a day or two if I can. Ah the joy and discovery and work of a newly aquired cruiser.... Wouldn't be fun if everything worked!

 

[TopGear]

Add my '92 to the list of brighter lights when operating the windows. Will try to throw the volt meter on the battery tomorrow to check voltage fluctuations. I've been putting off some alternator trouble-shooting for a while now because she otherwise runs great.

 

[RavenTai]

Ok must be a FJ-80 thing, that is completely opposite of my FZJ and all other vehicles I have ever seen, is the alt on those externally regulated?

WAG: I wonder if a common connection is causing it to not see all of the system voltage as current increases?

 

[jamot]

Raven,

Internally regulated alternator from what I remember on the 80. Yeah a strange "80 thing" but at least I don't feel as crazy as when it happened.

Meter on the battery at window roll up/down is a good point as well as a common point/junction/ground/connection being a possibility as you note.
Interested to put a meter at different points and lay the mystery that seems to haunt a few of us to rest...

 

[Arya Ebrahimi]

Sorry Raven, my '94 does it too...

 

[RavenTai]

Arya, your lights get Brighter when you put a load on?

Mine get dimmer when a load is put on (only at idle)

 

[kipper]

mine get brighter on load too. I betcha Slees harness fixes this...

 

[Arya Ebrahimi]

Arya, your lights get Brighter when you put a load on?

Mine get dimmer when a load is put on (only at idle)

Correct. Well sorta. When the windows are in motion I think the lights dim(honestly not sure), but I know for a fact that if you pull up on the switches when the windows are all the way up, the lights get brighter. The more switches you pull up, the brighter they get. If I pull all 4 it makes a remarkable difference. One of these days I'll get around to installing my slee headlight harness, I wonder if it will still have the same effect with the lights getting the power they deserve.

Ary

 

[PHAEDRUS]

Yup,
MIne doe anyways, slee harness wired direct to the battery.

My WAG is the alt has either a load or no load voltage regulator. SOOOOOO

You are at idle and lights are on and windows down. alt is putting out 14.5 volts and about 10 amps available to draw. you trip the motor switch and the alt puts out its max ampaerage as available to draw in the system. Not sure what it is but say 40 amps. the window motors will not need the additional amps so your lights get brighter???

if you have the windows all the way up the motors will try to turn but will not draw any amperage per say. the lights are in the circuit and suck up the excess amperage easily. just a WAG here so dont flame too hard.

Dave

 

[lowtops]

jamot,
I am the one who started the earlier thread eluded to by Raven. I have yet to figure it out. When I realized the alt. was internally regulated I moved on to other maintenance issues. If you find anything out please post your results. I agree with the others who said voltage regulator, but since it's internal I'm not sure what options we have. New alt???

PHAEDRUS,
Could you explain "WAG" for the new guy. (me) The best I could come up with is "Wild A$$ Guess"

 

[RavenTai]

PHAEDRUS,
Could you explain "WAG" for the new guy. (me) The best I could come up with is "Wild A$$ Guess"

You got it


PHAEDRUS, Alt regulation is more fine tuned than that, it is suppose to vary it's output in amps and match what is used to maintain a steady voltage (liek you said about 14.x volts )

at lower RPM's it max output it is able to deliver is decreased, if the total combined load exceeded what the alt can output in amps then the system voltage drops.

that fits well with my lights dimming when I roll up the windows at idle, but does not fit with them getting brighter, for some reason the regulator most be getting tricked, I only have WAG’s as to how.

Depending on how badly, how long and how often it is getting tricked it may overcharge the battery shortening its life.

 

[jamot]

Seems my brother in laws 96 FZE does it too. Also seems he hid the fact from me in shame until I brought the subject up. Very emotional for him..... I told him he was not alone.

I pretty much agree with phaedrus about the excess current finding an alternate path. I've seen it happen when a ground fails and electricity goes looking for an alternate one to use. Looking at it in that perspective it makes more sense to me.

I can live with that, sans actually doing a few test too, but........ brighter is definitely better, (for the headlights, dont really care about brighter dash lights), almost seems like a 50% increase, so will the slee headlight harness help ? Ignorant of it's existence to this point..

 

[PHAEDRUS]

Jamot,
the slee headlight harness is good for you......

wont help at all withe alt light phenomenon but it will increase your normal output by (and this is my personal experience) about 35-40% at low beam. even more on high beam. well worth the money and aside from playing wiht the grille its an easy install.
Dave

 

[nyk438]

My 91' started doing this after I put in a rebuilt alternator. Happened when I ran it through a mud pit, drove to fast...


I'm assuming the alternator has less amps then the stock? Causes lights to dim at idle and turn bright when RPM increased.

 

[jamot]

The slee harness is on the short list for this 80 after a few more tlc issues are finished. Looks worth the money. Thanks for the info...

I wonder how many with the brightening light syndrome have re-built/re-man alternators? I ask this because my other 91, which never experienced this had the stock alternator and I rebuilt it without replacing the regulator..... Where as my "new" 91 (light syndrome) has a shiny new denso alternator that had to have just been done by po..... Maybe some sort of slight difference in regulation or output... maybe...

Regardless, once I get a full day with her and get a meter out, I'll post if I make any revelations.....

Thanks again for everyones input on this.

 

[thorvald]

when i took mine out to get it tested, it had a reman sticker on it, pretty sure it was a toyota reman but not for certain. have to look and see if I can tell with it in there.

 

[Riley]

I think I might know why this is happening. I wonder where the "sense line" is for the regulator. In some regulator designs, the regulator measures the voltage at some other point other than the alternator output (i.e near or at the battery).

Let's say it senses it somewhere along the cable that feeds the electric windows. When you turn on the electric windows, that cable will have a small voltage drop along it as it powers the windows. To the regulator, it will look like the voltage at the battery is low and bump up the voltage it's feeding to the battery to keep it pegged at the set point.

That higher voltage (which is compensating for the voltage drop developed in the cable to feed the windows) is also fed to the lights directly without the same voltage drop (because it's in another cable and probably heavier cable).

To check out this theory, check the regulator and see where the sense wire connects to (I would think it's the lighter gauge wire). I bet it connects to another wire that is running from the battery to the windows. Also check which wire feeds the lights.

To fix it you would need to either run a heavier cable to the windows OR feed the regulator from a different point (in either case, don't worry about it).

When testing with the meter, measure at the battery and also at the regulator. I bet at the battery you will see differences when the window is powered on/off but not at the regulator.

Just a hunch.