19963.4lsr5
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Do you have the dome circuit wiring for your 99? If so can you post a copy of it so I can review it?
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Dome Light Question
- Thread starter 906-Runner
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906-Runner
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I believe this is the correct one, I found it on another thread about the dome light in a 99.
if the trip odo resets, that's sounding like a battery disconnect, which is really nonstandard unless one does this manually (e.g., removes the connector for one's safety or for testing). what you've just related seems to masquerade as a battery problem, but based on your earlier post, your battery maintains at 12.6v. i start to wonder if you might have a relay that's going bad or may not be fully seated. outright failure is fairly rare for relays, but not impossible or unheard-of. would you check to make sure they're seated? also a random question: do you know if the vehicle was ever flooded and took on water and/or mud way high in the engine room? any high-water line in the fusebox? far-fetched, but worth asking given that you've got other rando electrical issues.
did you check the current draw with everything off (no radio, no fan, engine off, no lights, no add-ons like a scangauge, and so on -- just nothing, as if you planned to leave it for a month)? there would be a small draw from the clock, but not much else. if you're getting more than a few dozen milliamps, you've definitely got a phantom load to fix, and though that may not be the root of the issue regarding your dome light, it's in league with these issues.
my $0.02: i don't think the dash (i'm gathering here, "dash" means the combo meter) is the problem. i could be off, of course, if for instance there's some unexpectedly janky wiring back there which /cough/ i would know nothing about, looking at my own vehicles /cough/ but... i would want to see what's going on with some of the big hitters like the radio. is it using the stock connector, or is it hardwired like i had to do with mine? do you have any indicator lights that simply don't light?
does your combo meter get warm or hot? whatever's causing a huge current draw (if that turns out to be what this is), would need to be dissipating a lot of heat, and would nearly but not totally max out the capacity of the fuse it's on.
another consideration: are the fuses all of the correct rating? so for instance, the dome light fuse should be 15A. that is allowing current sufficient to generate 200W to heat up something. i'm stunned your battery isn't run down after even a few minutes of this.
when issues like this get really deep, it's useful to make a 2D matrix with system components on one axis and tests on the other, and where those meet, record the result.
another edit: do your battery voltage (let's say 12.6v like before) and voltage measured across the terminals of the dome light socket equal each other?
and heck, something more to look into: would you disconnect all of the interior lights (see the diagram for which) *except* for the troublesome dome light, then see if it's still dim? are all the other interior lights dim, too? they all have the same main fuse, so presumably what happens to one, happens to all.
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19963.4lsr5
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As the 3rd Gen became more modern more and more things that use to he hard wired became distributed modules. You’re instrument cluster is no exception. It’s digital? Yes?
It looks like it is in control of your dome light controls and if your odo is crewing up.......I’d look for a cluster with similar milage and buy it and see how it behaves.
My old 04 Grand Cherokee had modules everywhere. Seats, doors, instrument cluster.....it was there way of saving money on copper wire and having a 2 wire communication bus sending info locally to control things.
In 99 Toyota completely changed their engine and body controls. Your milage may vary....
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It looks like it is in control of your dome light controls and if your odo is crewing up.......I’d look for a cluster with similar milage and buy it and see how it behaves.
My old 04 Grand Cherokee had modules everywhere. Seats, doors, instrument cluster.....it was there way of saving money on copper wire and having a 2 wire communication bus sending info locally to control things.
In 99 Toyota completely changed their engine and body controls. Your milage may vary....
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can't speak for exactly what's in [MENTION=274758]906-Runner[/MENTION] 's dash but mine is the same year and SR5 spec, and it's not digital. i've had the cluster off too many times to admit to, and it's the old-style boxy thing with spring-load twist lights and exposed traces all around the board, and three molexes to connect the silly thing to their extra-short cables.
19963.4lsr5
New member
The combination meter is the instrument cluster? If your 99 is still analog gauges without digital ODO is it the correct diagram. My 97 drawing shows something else in place of the combo meter.
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thanks for the reminder: on mine the gauges are analog. the odo is digital.
906-Runner
New member
I actually did try plugging in another dash from my 2000 parts vehicle, nothing changed. I ordered a volt meter to try testing continuity and power supply stuff to see where my draw is coming from. As far as I know it is not a flood vehicle but then again I don't really know much about its past. I've had it apart a few times and couldn't find any signs of a flood vehicle(sand every, fried electrical stuff, corrosion) but I really don't know where I would be looking specifically. My plan is to just pick away at it a little bit at a time and if I cant fix it I'll just deal with it until graduation next fall and buy something newer.
906-Runner
New member
Got my volt meter tester yesterday and tried it out today. I have continuity everywhere, I tested resistance as well and got around 1 Ohm between all connections except one. I had 12 Ohms between my dash and my radio; I’m guessing it must be pinched or something, but still barely connected? Any ideas how I could figure out what it is?
tl;dr: measure current in addition to resistance, to see if something is sucking power.
long version:
in addition to ohm readings, switch it over to amps and see what you get using the same technique and connections. ohms will tell you for instance that some device has internal resistance, and it's not out of the question that 12Ω simply is the sum total of your speakers. amperage though should help to determine if something is power-greedy when it shouldn't be. i wonder if there's something goofy with the stereo, such as it has a built-in sub that is always on and simply doesn't make any sound unless it gets signal. in my '95 pickup, i learned the hard way that the rear (jumpseat) speakers are active, and they will run down a battery if not specifically switched off. i had hooked a new stereo to *unswitched* +12v and had a separate manual switch for it. i came back the next day and -click- no power. after i recovered from the doomed feeling, i realized the error of my ways, and now in that vehicle i have two switches -- one for stereo on/off, and another for active rear speakers on/off. this came about because the stereo did not automatically turn off the rears when it was powered down. weird.
19963.4lsr5
New member
Using a test light and using the bright bulb- dim bulb-no bulb
If the OP isn’t mindful putting that meter of his to Amps he will blow the internal fuse. It can’t be used in the same way switched to amps as one does measuring voltage and resistance.
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If the OP isn’t mindful putting that meter of his to Amps he will blow the internal fuse. It can’t be used in the same way switched to amps as one does measuring voltage and resistance.
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good reminder. i was operating on the assumption (but we know what that makes of us) that OP would have the vehicle off and accessories off, and then commence testing in series with various suspect devices, to see which one(s) is/are using power without permission. i didn't make that super-clear... my bad.
in my '95 truck, there's a dash dimmer and it is scratchy and sometimes craps out some dash lights until i adjust it. i don't recall any rheostats used to control the interior lights in either the truck or my 4R, but if there's one that i can't recall, it would be very worth twiddling that.
in the absence of an actual rheostat, given the persistent symptom that all interior lights run dim if they run at all, then it's not a matter of say one loose lead to the dome light. we don't yet know if there's +12v to the dome light receptacle (as an easy one to test). if the battery measures 12.6v at the time of testing but when the dome light *ought to* light up in the ON position with the door shut, instead the dome light receptacle measures far lower voltage, then something seriously weird is happening. if the dome light receptacle (correctly) has 12.6v also at that time, i can't picture what would be functioning to dim it as if it had a rheostat, which is why i was wondering if a high-drain device such as a radio might be causing the dimming, but that still sounds far-fetched despite my inclination to think of it as a culprit.
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906-Runner
New member
I got a bit lost reading your posts, and have a total noob question. How am I supposed to test the dome plug for voltage without risking blowing the internal fuse on my meter?
set your DVM to the right range (unless it's auto-ranging) for DC voltage. for instance, one of my DVMs is auto-ranging and all i do is set it to DC. another one of mine has a rotary dial for DC 2-20v, so i use that when i use that DVM.
set the light switch to the position where it would be on, even though it's either dim or not getting power at all at the moment. turn on your DVM in the right range. with the dome bulb temporarily removed to make this easier, just hold one probe to each of the bayonet mounts. it doesn't matter which -- you'll either see positive voltage, like +12.60v or negative voltage like -12.60v. for our purposes we don't care whether positive or negative, but rather that it's getting continuity to the battery and nothing is dropping the voltage.
once you get a reading, check that against the battery directly so you can compare.
touching your DVM probes to the leads (one each, no bridging) is as harmless in the right DC range as directly measuring across the studs on the top of the battery. there should be no issue with blown fuses, since you're not going to exceed your DVM's maximum range by getting thousands of volts.
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19963.4lsr5
New member
He also needs to check that dome lamp voltage under load with the bulb installed and switch turned on.
Bad connections will show full voltage when not loaded. Under load the connections fail.
He only needs to be carefull in amps mode. If he tries reading a higher voltage than what he has his range set for it will just read OL or range etc.
Dumb question....OP you have the correct lamp in there correct? Not one that fits rated for 24v or a LED?
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Bad connections will show full voltage when not loaded. Under load the connections fail.
He only needs to be carefull in amps mode. If he tries reading a higher voltage than what he has his range set for it will just read OL or range etc.
Dumb question....OP you have the correct lamp in there correct? Not one that fits rated for 24v or a LED?
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906-Runner
New member
So I actually do have small LED panels in place of the stock bulbs, but those where installed and worked before I started testing as I mentioned in my first post.
906-Runner
New member
I tested between the prongs on the dome light and I'm only getting about 2 volts; clearly I have too much resistance somewhere but now I've got to track it down.
this is going to sound bizarre, unlikely and just wrong in the head, but it seriously sounds like it could be being run through your speakers. if i'm calculating this right, if you start with 12v dc and the circuit (this hypothetical messed-up circuit) with four 2Ω speakers is set up in a voltage divider arrangement, then 12v in becomes ~ 3v out. i mean, crazy-sounding but it bears some investigation.
if someone with way more electronics background than i have, could chime in, that would be great.
19963.4lsr5
New member
Did you pull the led out of the socket when you had 2v at the prongs?
What were you putting your black lead on for ground.
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906-Runner
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So I actually tested the socket it self without the led in place, that’s when I got two volts. I might be doing it wrong as far as testing cause I just had my red lead on one side and black on the other with my meter on volts
