Need help choosing a resistor again.

Thread Starter

GRNDPNDR

Joined Mar 1, 2012
540
You could try rewiring the LED between the indicator output and the +5V supply. It sounds like maybe the LED is switched between 5V and 12V.

Bob
I don't know how I'd do that without redesigning the circuit board. I want to try just using "regular strength" LEDs. and see what happens.

This is kind of the last remaining modification project on my list and the last thing I have left to get working right and then I'm done.
 

BobTPH

Joined Jun 5, 2013
2,734
Circuit boards can be patched. You can cut traces and solder in new jumpers. I assumed this is just a one-off project, not a production issue.

Bob
 

Thread Starter

GRNDPNDR

Joined Mar 1, 2012
540
Circuit boards can be patched. You can cut traces and solder in new jumpers. I assumed this is just a one-off project, not a production issue.

Bob
it is a one off, but I don't feel like getting that involved in it when I'm sure there's a simpler solution.
 

MrAl

Joined Jun 17, 2014
7,884
Hello there,

It sounds like it could be a switch leakage problem. This is rare but it does happen.
This kind of problem means that there is still some current flow though the switch when it is turned into the 'off' position. You would think all current would be zero, but high brightness LEDs have a very low "first light" threshold and so you may be seeing that tiny but significant current through the LED light the LED up slightly.

Another problem is leakage through another unknown impedance. This would act similar to the leaky switch syndrome.

EIther way, a resistor from the LED side of the switch to ground will shunt the current to ground. A 1k should do the trick, but perhaps even a 5k or 10k might do it. Use the highest value you can, but also make sure that it turns off WITHOUT the new resistor when the ignition is turned off.

Alternately, a zener in series with the LED or even maybe a silicon diode in series with the LED.

Still yet another possibility is a 1k resistor ACROSS the LED. That will shunt most of the current if the current is low anyway and will not draw too much when it is on.
 

Thread Starter

GRNDPNDR

Joined Mar 1, 2012
540
I don't have the room to start putting in resistors across LED,s or running them to ground, I can't change much except resistors or bulbs that's it.

Here's the bottom line, with the factory "regular bright" LEDs installed they remain off when they're supposed to be off and function as normal.

Doing absolutely nothing more than swapping those orange LEDs for super bright blue ones, the blue ones remain dimly lit at all times.
So what's the explanation for that?

On top of that I have to be careful when changing resistances because the computer on the vehicle handles a lot of functions or diagnostics based on the resistance of certain circuits. If I start changing out resistors that do something more than just control the current to lights then I could end up changing the way the 4WD circuit works or even break it completely.

I got the wiring harness for it, so I should at least be able to do some better testing of it.
 

MrAl

Joined Jun 17, 2014
7,884
I don't have the room to start putting in resistors across LED,s or running them to ground, I can't change much except resistors or bulbs that's it.

Here's the bottom line, with the factory "regular bright" LEDs installed they remain off when they're supposed to be off and function as normal.

Doing absolutely nothing more than swapping those orange LEDs for super bright blue ones, the blue ones remain dimly lit at all times.
So what's the explanation for that?

On top of that I have to be careful when changing resistances because the computer on the vehicle handles a lot of functions or diagnostics based on the resistance of certain circuits. If I start changing out resistors that do something more than just control the current to lights then I could end up changing the way the 4WD circuit works or even break it completely.

I got the wiring harness for it, so I should at least be able to do some better testing of it.
Hello again,

Well if you dont have room to do ANYTHING different, then you will have to do everything the SAME
Replace the high brightness blue's with regular standard brightness LEDs and see what happens.
If that's your only option, that's your only option.

Various scenarios have been given to you to tell you why this might be happening and the solutions you seem to not be able to do, so you are stuck with doing it the old way.

There are also surface mount resistors, not sure if you can deal with them or not.
 

Thread Starter

GRNDPNDR

Joined Mar 1, 2012
540
I'm going to try standard LEDs, I've ordered a few different types so I'll see what happens, I also have a second switch to use in my truck while I experiment with this one, and the wiring harness so I can plug it and breakout the pins to make it easier to test the pins.

I'm considering SMDs as an option, but first I'm going to wait until my standard LEDs arrive and give those a shot.

I'd be both surprised, and not surprised if I dropped in standard LEDs and it worked without issue..... I'm telling you, automotive electrical can be downright strange sometimes.
 

MrAl

Joined Jun 17, 2014
7,884
I'm going to try standard LEDs, I've ordered a few different types so I'll see what happens, I also have a second switch to use in my truck while I experiment with this one, and the wiring harness so I can plug it and breakout the pins to make it easier to test the pins.

I'm considering SMDs as an option, but first I'm going to wait until my standard LEDs arrive and give those a shot.

I'd be both surprised, and not surprised if I dropped in standard LEDs and it worked without issue..... I'm telling you, automotive electrical can be downright strange sometimes.
Hi again,

Sounds like a good plan. Yeah i know what you mean about automotiver electrical stuff, sometimes not what we expect. My alternator on my car takes a full second or two to bring the battery back up to the normal charge voltage after i start the engine. My older car never took any time at all.
 

Thread Starter

GRNDPNDR

Joined Mar 1, 2012
540
After plugging in an unmodified 4WD switch I've come to realize that there isn't actually any problem, and the factory orange LEDs do in fact remain on very dimly lit any time there's power.

Its just nearly unnoticeable in the day time because the factory LEDs aren't super brights.

So this is just a function of the switch, and if I do use standard bright LEDs it'll work the same,.

This is good to know.
 

MrAl

Joined Jun 17, 2014
7,884
After plugging in an unmodified 4WD switch I've come to realize that there isn't actually any problem, and the factory orange LEDs do in fact remain on very dimly lit any time there's power.

Its just nearly unnoticeable in the day time because the factory LEDs aren't super brights.

So this is just a function of the switch, and if I do use standard bright LEDs it'll work the same,.

This is good to know.
Hi,

Oh that's interesting. What else would be interesting would be to track down the cause of that little light up problem. Maybe there is something else in the circuit we dont know about yet. If the switch is leaky, you may be able to tell with a 12v supply and a sensitive current meter. The Ohms function may or may not show anything wrong.
 

Thread Starter

GRNDPNDR

Joined Mar 1, 2012
540
It would actually be kind of nice to sort it out, but I feel like they probably designed it that way. Perhaps then it's some kind of safety type feature that lets you know if something is wrong with a part of that particular circuit or something.
As mentioned above, the LEDs have multiple sources to receive power. They're all connected to a single trace that then goes to others parts of the board going back to other pins that have power, so it might be kind of hard to trace what's actually keeping the bulbs lit.

Like I said though I can't just go changing the resistors all out because it could affect how the circuit functions or how the vehicle computers receives it's signal.
 

MisterBill2

Joined Jan 23, 2018
7,713
It has been a while since I visited this string, and I see there is no solution yet. But if the LEDs stay on when the switch is off, and if that is indeed a problem, then instead of a series resistor, try a shunt resistor across the LED. Try a 1000 ohm (1K) resistor and see if that is able to shunt enough current to reduce the brightness to an acceptable value. But don't go to less than 100 ohms because that will draw too much current when they should be on.
 

MrAl

Joined Jun 17, 2014
7,884
It has been a while since I visited this string, and I see there is no solution yet. But if the LEDs stay on when the switch is off, and if that is indeed a problem, then instead of a series resistor, try a shunt resistor across the LED. Try a 1000 ohm (1K) resistor and see if that is able to shunt enough current to reduce the brightness to an acceptable value. But don't go to less than 100 ohms because that will draw too much current when they should be on.
Hi,

That has been considered and rejected previously in this thread.
After the OP's most recent post i see why he doesnt want to do this so strongly now.
 

MrAl

Joined Jun 17, 2014
7,884
It would actually be kind of nice to sort it out, but I feel like they probably designed it that way. Perhaps then it's some kind of safety type feature that lets you know if something is wrong with a part of that particular circuit or something.
As mentioned above, the LEDs have multiple sources to receive power. They're all connected to a single trace that then goes to others parts of the board going back to other pins that have power, so it might be kind of hard to trace what's actually keeping the bulbs lit.

Like I said though I can't just go changing the resistors all out because it could affect how the circuit functions or how the vehicle computers receives it's signal.
Hi,

Oh yes that is the best point i have read so far for NOT doing anything fancy which involves just about any mod. That is, unless you feel like experimenting a little and are ready to reset your monitors if needed and you have the tool to do that also.

What else you say makes a lot of sense too now. The LED comes on very slightly to show that the circuit is working. So it's on part way for perhaps a good reason. It comes on all the way when it is appropriate, and stays only dim when necessary. That could all be so true. Perhaps a forum for your particular vehicle could help more on this issue because there would be many other users with the same type of car and maybe even same model and they may understand this issue more thoroughly.

Usually when we make a mod of any kind we know the entire circuit first, and that in this case could even involve the ECU too. It could be detecting a tiny current just to show that the LED is not burnt open or any other part of that circuit is not open circuited.
 

MisterBill2

Joined Jan 23, 2018
7,713
Hi,

That has been considered and rejected previously in this thread.
After the OP's most recent post i see why he doesn't want to do this so strongly now.
OK, sorry about being redundant. I just went back through and saw the comments from Mr.Al in #24. . And I should have examined those photos right near the beginning. In another thread there was quite a discussion about the minimum voltage to light an LED just a bit. It seems that some of them will glow with a very small current at way less than the specified voltage. That is interesting.
 

Thread Starter

GRNDPNDR

Joined Mar 1, 2012
540
Knowing that the LEDs remain on in all of our vehicles means I didn't o anything so wrong, so I'm relieved about that. I actually brought this up in a facebook group and surprised many people with this information.
3 people went to check their 4WD switches and came back totally surprised that the LEDs do remain lit and they've never noticed it.
I only discovered this by using super bright LEDs that are much brighter at lower current levels.
I've only done some very basic testing and looking at the board, but I THINK if one of those LEDs were to go out it would break the circuit to whichever mode was out...so if 4HI burned out, then I think it would prevent you from switching to 4HI mode and would throw up either the "Lamp out" warning (not likely for an onboard LED) or would throw the "Serv 4WD" message due to the circuit not working.


I actually did spend some time on a forum dedicated to our trucks, I've been a member for years, problem is as much as those guys go crazy doing insane mods, I've caught nothing but flak and ridicule for "constantly breaking things" and "making a mess of it" even though everything is done clean and proper.

They all show off their blue interiors which is done by using nothing more than drop in bulbs, and people ask how they can do the switches and things I've done they reply with things like "man I'd hate to be the next owner of your truck", but I have videos detailing the process and showing the work.

I've single handedly proven a lot of information wrong about our gauge clusters (which is actually a computer too), I've had mine completely apart, shown off inside, how they work, how to repair what I broke properly, etc .... basically just thrown out TONS of excellent info about our cluster that nobody (even Chrysler) knew, and when I do I have everyone down my throat about how I don't know jack even though the literal proof is in their face in my video.

If it doesn't bolt on, or replace easily, they don't know jack.
Not a single one of them knows the internal workings of the power window circuit. I mean these guys can't even swap LED bulbs in their headlights or dome lights because nobody seems to know that our trucks use changes in resistance to measure a lot of things.

When you swap out filament bulbs for LEDs funny things happen. Lights flicker on and off rapidly, or they don't work, or won't work unless you turn on certain bulbs all at the same time, because when you swap LEDs you change the resistance so you need to add resistors with the LEDs to make the circuit function again.
When there's a change in resistance in the lighting circuits you get a "Lamp out" message as well.

This is a festoon bulb in my reading lights. Without the resistor on each bulb they remain dimly lit at all times and will onyl turn on when you turn on ALL of them.
Add in the resistors and the problem goes away and lights function as normal.

So yeah, those guys aren't exactly a wealth of knowledge on the electric side of things.
 

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MrAl

Joined Jun 17, 2014
7,884
Knowing that the LEDs remain on in all of our vehicles means I didn't o anything so wrong, so I'm relieved about that. I actually brought this up in a facebook group and surprised many people with this information.
3 people went to check their 4WD switches and came back totally surprised that the LEDs do remain lit and they've never noticed it.
I only discovered this by using super bright LEDs that are much brighter at lower current levels.
I've only done some very basic testing and looking at the board, but I THINK if one of those LEDs were to go out it would break the circuit to whichever mode was out...so if 4HI burned out, then I think it would prevent you from switching to 4HI mode and would throw up either the "Lamp out" warning (not likely for an onboard LED) or would throw the "Serv 4WD" message due to the circuit not working.


I actually did spend some time on a forum dedicated to our trucks, I've been a member for years, problem is as much as those guys go crazy doing insane mods, I've caught nothing but flak and ridicule for "constantly breaking things" and "making a mess of it" even though everything is done clean and proper.

They all show off their blue interiors which is done by using nothing more than drop in bulbs, and people ask how they can do the switches and things I've done they reply with things like "man I'd hate to be the next owner of your truck", but I have videos detailing the process and showing the work.

I've single handedly proven a lot of information wrong about our gauge clusters (which is actually a computer too), I've had mine completely apart, shown off inside, how they work, how to repair what I broke properly, etc .... basically just thrown out TONS of excellent info about our cluster that nobody (even Chrysler) knew, and when I do I have everyone down my throat about how I don't know jack even though the literal proof is in their face in my video.

If it doesn't bolt on, or replace easily, they don't know jack.
Not a single one of them knows the internal workings of the power window circuit. I mean these guys can't even swap LED bulbs in their headlights or dome lights because nobody seems to know that our trucks use changes in resistance to measure a lot of things.

When you swap out filament bulbs for LEDs funny things happen. Lights flicker on and off rapidly, or they don't work, or won't work unless you turn on certain bulbs all at the same time, because when you swap LEDs you change the resistance so you need to add resistors with the LEDs to make the circuit function again.
When there's a change in resistance in the lighting circuits you get a "Lamp out" message as well.

This is a festoon bulb in my reading lights. Without the resistor on each bulb they remain dimly lit at all times and will onyl turn on when you turn on ALL of them.
Add in the resistors and the problem goes away and lights function as normal.

So yeah, those guys aren't exactly a wealth of knowledge on the electric side of things.
Hi again,

Oh sorry to hear about your bad experiences with the dedicated forums. Sometimes users can be very, well let's just say, less than helpful :)

I have the same problem with my car, which is somewhat new technology for me because the last car i had before this one did not have a computer that's how old it was. So i never had the monitor issues and stuff like that until i got the newer car. The dedicated sites for that car do help sometimes though so i continue to use them as well as do my own searches and some experimenting.

What surprised me about your situation with the possible change of headlamps from regular to LED was that when you go to buy the LED headlamps a lot of times those little computer fooler things come up too, which prevent blinking and such. So i would think that someone would have know about that. Maybe no body there did the actual conversion yet they just talked about doing it perhaps.

In any case good luck with your future car repairs :)

One final thought...
When you replace the regular LED's with the high brightness LED's does the amount that the new LED's are lit bother you more than the regular ones? That is, are they that much brighter than the standard LEDs when they are supposed to be 'off' ?
 

MrAl

Joined Jun 17, 2014
7,884
OK, sorry about being redundant. I just went back through and saw the comments from Mr.Al in #24. . And I should have examined those photos right near the beginning. In another thread there was quite a discussion about the minimum voltage to light an LED just a bit. It seems that some of them will glow with a very small current at way less than the specified voltage. That is interesting.
Hi,

Hey no problem really, just wanted to mention that.

Yeah it's amazing to me too how some of these LED's light up with so little current. I used two super bright white LED's to make an emergency light back some years ago before we had a big hurricane hit here. It's just two 5mm white LEDs in series and in series with a somewhat high value resistor to limit current to a very low level, and connected to a 12 volt, 7 ampere hour lead acid battery :)
Because the current is so very low and the battery so 'big' (7AHr) the light will stay lit for an estimated three months or more. The light output is just enough to see your way around with in the dark.
I was lucky i built this (although it's hardly a very big project really) before a hurricane hit a few years back that took out our electric for four or five full days in a row. I had the emergency light going the whole time with confidence it would go several months. It's amazing how little light we need when we are faced with complete and total darkness.
 

Thread Starter

GRNDPNDR

Joined Mar 1, 2012
540
My initial concern with the LEDs being on when they should off was that this was not known information. In all the years of people owning these trucks, in the literal millions of threads posted on forums, not once have I ever seen this mentioned. It isn't mentioned in the factory service manual which actually states that the lights are off when that mode isn't selected.

Basically not one single person knew that these LEDs remain on in when they're supposed to be off. I just had a number of people surprised when I brought this up and they actually went to look.

So what bothered me initially was that I thought I had done something wrong and the LEDs were remaining lit due to a fault of my own, but if this is how they function normally then I'm ok with that.

I would like to crank down the brightness a little bit, they're 13,000 MCD, they're brighter in their "off" state than the original LEDs were in their "on" state lol. That's why I've ordered a couple of different varieties of blue LEDs, I'll see which one works best and appears dimmest while "off" and brightest while on, leave it at that and call it done. :)

As for the guys on the dedicated forums....well I don't know, they know their stuff for sure, just not when it comes to electrical at all and even the people who know you need resistors when converting to LEDs never mention it to the guys who's lights are flickering.

There is a TON of parroting going on. For instance, with the cluster:
everyone says you can buy a cluster from the wreckers and have a dealership send it back to be reprogrammed for the correct odometer and engine hours.
You can't, or at very least the dealerships won't send it in....3 major dealerships and a call to the company directly verified this information.

Everyone also says many companies can reprogram the cluster. Again, some calls and fact checking later it turns out this model year cluster has it's chips locked and cannot be accessed even by third party companies.

The clusters have a self test feature. EVERYBODY has said this is a calibration, and if you're needles are out of whack (or literally any other problem) just run this calibration and it will fix it.
It does not. I have a video literally proving this and showing 100% that it is only a test...... everyone gives me flak for breaking my cluster, still says its a recalibration.

That's just a "small" example of the kind of crap I keep having to deal with while doing any kind of modification work.....successfully...... on my own vehicle.
 

MrAl

Joined Jun 17, 2014
7,884
My initial concern with the LEDs being on when they should off was that this was not known information. In all the years of people owning these trucks, in the literal millions of threads posted on forums, not once have I ever seen this mentioned. It isn't mentioned in the factory service manual which actually states that the lights are off when that mode isn't selected.

Basically not one single person knew that these LEDs remain on in when they're supposed to be off. I just had a number of people surprised when I brought this up and they actually went to look.

So what bothered me initially was that I thought I had done something wrong and the LEDs were remaining lit due to a fault of my own, but if this is how they function normally then I'm ok with that.

I would like to crank down the brightness a little bit, they're 13,000 MCD, they're brighter in their "off" state than the original LEDs were in their "on" state lol. That's why I've ordered a couple of different varieties of blue LEDs, I'll see which one works best and appears dimmest while "off" and brightest while on, leave it at that and call it done. :)

As for the guys on the dedicated forums....well I don't know, they know their stuff for sure, just not when it comes to electrical at all and even the people who know you need resistors when converting to LEDs never mention it to the guys who's lights are flickering.

There is a TON of parroting going on. For instance, with the cluster:
everyone says you can buy a cluster from the wreckers and have a dealership send it back to be reprogrammed for the correct odometer and engine hours.
You can't, or at very least the dealerships won't send it in....3 major dealerships and a call to the company directly verified this information.

Everyone also says many companies can reprogram the cluster. Again, some calls and fact checking later it turns out this model year cluster has it's chips locked and cannot be accessed even by third party companies.

The clusters have a self test feature. EVERYBODY has said this is a calibration, and if you're needles are out of whack (or literally any other problem) just run this calibration and it will fix it.
It does not. I have a video literally proving this and showing 100% that it is only a test...... everyone gives me flak for breaking my cluster, still says its a recalibration.

That's just a "small" example of the kind of crap I keep having to deal with while doing any kind of modification work.....successfully...... on my own vehicle.
Hi,

Oh, dont get me started :)
For example, on my hatchback wagon the gas springs that hold the tail door open went bad so the door would not stay open. On the web, they all talk about replacing the two gas springs 1,2,3. NEVER mention the little end clips at the end of each gas spring. The question is, are the little clips really needed or not. The old ones had the holes for them but not the clips, and the new set had the clips installed but they have to be taken out to install then maybe put back in. BUT, no mention whatsoever on ANY site after viewing multiple sites and videos. Just doesnt make sense. IT's hard to believe that no one else ran into this problem that took the time to make a video for that very same make and model and year, just too hard to believe.
 
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