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Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go hereXJ (84-01)
All OEM related XJ specific tech. Examples, no start, general maintenance or anything that's stock.
Engine: 4.0, new lifters valve job with new springs and exhaust valves, preload set with shims
Are the LEDs even compatible with a dimmer??
If not they wont work right at all. I know in houses dimmers have to be compatible with LED or they just wont work right. you have to buy the LEDs that say DIMMABLE and the dimmer that says LED compatible.
Same is true for the motion sensing 'dusk to dawn' lights, if they aren’t compatible it wont work .
Last edited by 97grand4.0; 08-13-2020 at 07:30 AM.
Are the LEDs even compatible with a dimmer??
If not they wont work right at all. I know in houses dimmers have to be compatible with LED or they just wont work right. you have to buy the LEDs that say DIMMABLE and the dimmer that says LED compatible.
Same is true for the motion sensing 'dusk to dawn' lights, if they aren’t compatible it wont work .
Thanks! Good thinking. Hmm These are definitely not dimmable LEDs. They are some cheapo ones from Amazon that don't even have a spec sheet.
Non dimmable ones should work if they get enough voltage, just not dim, but they might take a higher voltage to turn on. This is one idea that would need to be tested. I only get the right side of the gauges turn on consistently, the left side is off usually but sometimes flickers on. The shifter lights are always on. The LEDs (that do turn on) turn on when I crank the headlight switch all the way. This is why I was thinking of just trying another set of LEDs (maybe even dimmable ones) that actually have a spec sheet in case the ones I have just need too high of a voltage to work consistently.
They are also LEDs with polarity. Meaning they have to be rotated the right way around. I've tried all orientations and different bulbs.I don't think that's the case.
dont know about your '91, but my '96ers have a poor design that allows all fan motor blower current to go directly thru the ignition switch
check the circuit diagram for yours, but if it is the same, I added relays behind the PS kick panel..one for each speed is needed
Interesting!
How much current gets drawn usually for the blower motor?
Are you thinking in general this might be a good fix if I'm wiring in a new fuse box with ignition switched power from the battery, or are you thinking this might contribute to issues in other circuits like the lights?
Year: 1998 Classic (I'll get it running soon....) and 02 Grand
Model: Cherokee (XJ)
Engine: 4.0
Originally Posted by awg
meanwhile, the ignition switch, and every other item in the circuit is getting all that current.
No, that's not how it works. Only the device that is drawing the excess current gets the excess current. The others see reduced voltage during that current draw.
Originally Posted by awg
It will not help solve any other lighting or electrical issues.
Engine: 4.0, new lifters valve job with new springs and exhaust valves, preload set with shims
[QUOTE=BlueRidgeMark;3616547]No, that's not how it works. Only the device that is drawing the excess current gets the excess current. The others see reduced voltage during that current draw.
He's saying the blower is wired through the ignition switch on the 96.., if that's true, the ignition switch would indeed see whatever it normally does plus whatever current the blower is drawing.
Engine: 4.0, new lifters valve job with new springs and exhaust valves, preload set with shims
[QUOTE=moonsandals;3616531]Thanks! Good thinking. Hmm These are definitely not dimmable LEDs. They are some cheapo ones from Amazon that don't even have a spec sheet.
Well by definition an LED is a light emitting diode, diodes require a forward bias to turn on, usually .7 vdc for silicon, .6 for germanium.
Thats not much, but you also don't know if they have a dropping resistor in them to limit the current. I would bet they do if they plug into 12v. As you mention they are polarized as well, this is because the anode has to be more positive than the cathode, ie, forward biased so your forward bias occurs across the junction.
Last edited by 97grand4.0; 08-14-2020 at 09:59 AM.
Why I initially created this thread
Just to give a bit more context on where my head was at when I first created this thread, I had been googling the issue since I had just fixed another issue on the circuit that was causing my instrument lights to go out.
From my google searches, I was under the impression it was a common issue with the instrument lights being dim, and I could not see many solutions posted. This is why I was coming off, maybe a little hot, with specifically asking if anyone has done anything like a relay before (because, again I was under the impression this was a common issue that doesn't get resolved, and I was wondering if I missed some fix somewhere on this).
After this thread kind of went sideways, I pulled those searches back up and quickly threw them into a table.
I've only found a total of 17 issues in my google search (fewer threads, but often a number of people posting or highjacking those threads with their own issues) related to the instrument lights.
So not a massive problem. Enough for my google searches to have pages of results, but nothing nearly as common as the headlight issues or door lock/ power windows issues.
Since I had that in Excel already I threw together a few pie charts to visualize how the issues were distributed.
So based on this, most of the issues people have are due to the light just straight up not working. And the majority of those were due to a short and blowing the parking brake fuse (actually a similar issue to what I had just resolved). On top of this are posts of people just asking about LEDs, which isn't really an issue, but just seemed to pad my google search results.
So I was way off base in what I assumed the scope of this issue was. I thought it was something more widespread than it is and was just trying to collect information and ideas when I first created this thread.
I'm guessing others in this thread were aware that this isn't a common issue in itself, and I'm guessing that's why we were misaligned.
What I am actually doing about MY issue
Now, the thread is clearly turning into an investigation into my own issue.
I totally welcome advice on actually fixing it. And although maybe it wasn't obvious, I personally don't do anything without testing first. I am VERY thorough and structured. Just because I was raising a hypothesis earlier or spitballing doesn't mean I was going to jump into doing anything without testing. I just got finished with 2 days of tracing wires, and a few weeks ago spent a day cutting out and repairing other wiring problems from the PO of this Jeep. I have a multimeter and use it. I'm not some cowboy cutting up my wiring harness ***** nilly.
In general, this is my plan. I lay this out now (based on the pesky hypothsis I raised earlier in the thread) so I can just work through it in a structured way down in my garage. I don't like going in without a plan:
I've got to get most of the wires back in place after my previous repair. Mostly need to connect the connectors in the kick panel, tidy up fuses, etc to make sure that's all good before I try to diagnose another issue
It's happening anyways when I install my aux power fuse box so I might as well do it right away - I'll tie the interior ground into the M8 stud as Cruiser suggested. This will just be adding the ground, not adding the fuse box. I'm keeping it simple and one thing at a time.
Test voltages for the lights, and maybe continuity on the flex circuit (it tends to look tarnished).
Test continuity at the lights/ gauges to ground
If low voltage at lights, work backwards. Focus on voltage at headlight switch next and work backwards.
If low voltage at headlight switch/ dimmer switch then look at replacing the switch (unlikely; pretty damn new switch but I would need to rule it out first)
If low voltage behind headlight switch, then.. could be anything. Look through connections, clean connections, check for pinched wires, etc.
If sufficient voltage at lights, try other LEDs with a known min voltage
Seem reasonable?
So the question is:
What's a reasonable voltage to have at the light sockets? 11.5 V? More? Less? When should I start looking at the headlight switch?
Niceeee, another Excel nerd like myself. And for what it's worth, I, for one, enjoyed reading your spitballing during the first part of this thread.
I think your action plan sounds pretty reasonable. Only change I might suggest would be to test the voltage into the dimmer switch and out of the dimmer switch first. If that's your issue then you'll save yourself effort testing other circuits. If it's not, well, then go back to your plan and test all the likely culprits in the circuit. And come to think of it, before you do anything, you should improve the ground as per Cruiser54 - the man is a wealth of knowledge on these old gals.
Niceeee, another Excel nerd like myself. And for what it's worth, I, for one, enjoyed reading your spitballing during the first part of this thread.
I think your action plan sounds pretty reasonable. Only change I might suggest would be to test the voltage into the dimmer switch and out of the dimmer switch first. If that's your issue then you'll save yourself effort testing other circuits. If it's not, well, then go back to your plan and test all the likely culprits in the circuit. And come to think of it, before you do anything, you should improve the ground as per Cruiser54 - the man is a wealth of knowledge on these old gals.
Thanks! I'm my line of work, looking at things like this and crunching some numbers is necessary. Some people might not get it but there's some value in thinking like that as long as you don't convince yourself something is true without evidence.
Although that Excel table is..much milder than usual. My wife however looked over my shoulder and said something to the tune of "it figures". Lol.
Thanks for the feedback. Honestly I was trying not to probe the headlight switch since I have the connector zip tied on haha. It's on there good and I could cut it off easy enough but seemed like something I wanted to avoid. But I'm not sure where is best to test voltage on the instrument cluster. It's really just that flex board then a light. So I guess I'd have to probe that. So I guess the dimmer isn't much worse than that.
Today I did the ground improvement that Cruiser suggested. I was putting all the wires back together after another repair (another, previous problem) and added the ground wire at the same time. It didn't change the instrument lights at all, but I feel better and I'll use the M8 stud as my ground point when I wire in my aux power fuse box.
Drove the Jeep (carefully) to my local shop around the corner. He did the brakes a month ago and I noticed a brake fluid leak so brought it back to him today to sort out. He seemed really concerned so he's going to fix it ASAP.
Once I get it back, I'll pull the gauges again to test voltage. Then I'll wire in the fuse box.
Thanks! Good thinking. Hmm These are definitely not dimmable LEDs. They are some cheapo ones from Amazon that don't even have a spec sheet.
Well by definition an LED is a light emitting diode, diodes require a forward bias to turn on, usually .7 vdc for silicon, .6 for germanium.
Thats not much, but you also don't know if they have a dropping resistor in them to limit the current. I would bet they do if they plug into 12v. As you mention they are polarized as well, this is because the anode has to be more positive than the cathode, ie, forward biased so your forward bias occurs across the junction.
Sorry it looks like the full quote didn't come through in your post, so I hope I'm reading the correct context.
That's interesting!
I'm no expert, so I was basing my numbers off of Wikipedia and online sources. Those give me forward voltage numbers much higher than yours (more like 1.8 to 3.3 volts per LED). So, according to those websites, you can get something like 3 LEDs in a bulb X 3 volts (or whatever the forward voltage is) = 9 volts. Plus resistors. This seems to line up with some spec sheets I could find online for automotive LED bulbs.
My bulbs definitely have three LED boards on them, and are blue, so I understood they should need a higher voltage. More like 3x 3.3 = 9.9 Volts plus resistors. Of course, I'd need a spec sheet or test to know for sure and you can get LED bulbs with a single LED on them which would cut the voltage down by 1/3 and would be a lot less likely to cut out on a circuit like this.
This is resolved. Super corroded socket seems to be the culprit.
I had the XJ at a shop a couple weeks ago for another issue (blown PARK fuse) that I thought might be linked to work they previously did (it was being tripped by the brake fluid level sensor; the shop replaced front brakes so I thought it could be indicating a brake fluid leak).
They needed to investigate the short circuit so they pulled the instrument cluster, and while doing so they replaced most of the bulbs with incandescent dimmable bulbs. They seem to really hate LEDs.
They knew I was in a rush to go camping so they gave me the car back without actually figuring out the issue with the short circuit. They went as far as confirming it's not a brake leak, but had to throw the dash back together quickly so I could go.
Everything but the right turn signal lit up when I got it back. But this got me wondering that my issue with the instrument cluster lights might be a bad bulb socket that just moved around when they replaced the bulbs. Keep in mind it's only one bulb that never lights up. Normally bits been a backlight. This time it's the turn signal.
I bought new LEDs (some glass dimmable ones, also some 9 V non dimmable ones) and new bulb sockets from superbrightLEDs.
Today after my wife and I finished working on our new bike, I had a bit of time to fix the turn signal bulb, so I pulled the cluster. I wanted to measure voltage at each socket, but it's a bit awkward to do alone and my (pregnant, at that point very tired) wife left me to have a nap and couldn't help me. So I settled on inspecting the bulbs, sockets and the circuit board/ flexible board as a first step.
The bulb socket was indeed very corroded looking. I tried replacing with one of the new sockets that I bought but the plastic housing on the new socket wasn't quite right and it fit too tight when you twisted it to lock it in. So I pulled the copper contacts out of the new one and replaced the old contacts in the old socket. Very easy to do. Also the flex film was very corroded so I cleaned it with alcohol. And bam. It worked.
I then replaced all bulbs back with LEDs. Turns out some of the glass dimmable ones broke in shipping so I didn't have enough for the whole dash so I used the non dimmable 9V ones. So I don't have dimmable bulbs unless I wanted to use the incandescent ones (which both me and my wife are not a fan of).
I went through the rest, refreshed socket contacts as needed, cleaned the copper film with alcohol, replaced with 9 V LEDs and after reassembly everything works.
At the end of the day, I didn't follow the steps I had planned and I'm not sure how much voltage it's actually getting (definitely more than 9V; I can turn the dimmer quite a bit before they shut off) but it's really obvious there was an issue with the contacts being corroded so I'm glad that repair has made the lights work again.
If anyone wants photos on how to swap out the socket contacts with new ones I could attach those here.
Last edited by moonsandals; 09-05-2020 at 07:15 PM.
08-12-2020, 10:59 PM
talking about relays
