Wiring experts: plz help identify short circuit

[Rickl]

Originally Posted by six50joe

The actual DOME fuse is in the box to the right of the engine. I'm wondering if it's possible to tap to that one and wire through the firewall. I haven't taken a close look at that area yet, and so have no idea at the moment whether that could be done or would be difficult / impossible. If it is, any other thoughts on getting a 12V lead to BLU/YEL?

There are always rubber grommets or plugs on the firewall which makes it real easy to get a small wire into the engine compartment. On the other hand there are probably several fuses in the interior fuse panel that would serve the same purpose
.

Originally Posted by Dr. Dyno

Besides why should Rickl have all the fun.

Fred, you have always been a "big man" in my eyes, but if you are able to hang upside down and work on that junction box, 4" in front of your nose, I'm now picturing you about 4'0" tall, 98 lbs, and spineless.

I can't say I remember it being that much fun the last time I tried to get my 6'4", 230 lbs back out from under the dash. Thought I might have to call the fire department.

[Dr. Dyno]

Originally Posted by Rickl

Fred, you have always been a "big man" in my eyes, but if you are able to hang upside down and work on that junction box, 4" in front of your nose, I'm now picturing you about 4'0" tall, 98 lbs, and spineless.

I can't say I remember it being that much fun the last time I tried to get my 6'4", 230 lbs back out from under the dash. Thought I might have to call the fire department.

Rick, you've got me by 6" and 60 lbs and yes, I do know the feeling of laying face up on the floor with the door sill & seat prodding into me and wearing two pair of reading glasses to see stuff at my nose. And then wiggling out and waiting five minutes to be able to stand again!

And, altho I haven't been following this thread blow by blow, I can't help but think it's something simple. Obviously the lights have to get power and ground which I'm sure you've covered, but short of a lot of smoke and melted wire or a simple pin pushed out at a connector I can't imagine any other failure mode. I'm afraid smoke and more damage is what may happen with cutting, splicing and bypassing.

I'd love to get my hands and my filament-bulb 12V test light on it. I wouldn't even trust my meter or my LED 12V test light since they don't give a load the would find a weak connection. I the meantime let the saga continue as long as you're willing to type.

BTW, don't tell Joe, but I might even buy at Wendy's just for the fun of troubleshooting his RAV.

[Rickl]

Originally Posted by Dr. Dyno

I'd love to get my hands and my filament-bulb 12V test light on it. I wouldn't even trust my meter or my LED 12V test light since they don't give a load the would find a weak connection.

BTW, don't tell Joe, but I might even buy at Wendy's just for the fun of troubleshooting his RAV.

The testing done so far makes me suspect that Joe's water leak has created some corrosion in the junction box, creating a high resistance connection to the ceiling lights. As you say this type of problem is better diagnosed with a test light, compared to a voltmeter. If Joe were to measure the voltage inside the dome light it is possible he could read 12v with a voltmeter and yet a test light would not light. The reason being (for those that don't know) is that the voltmeter draws no current (almost none) and therefore no voltage would be dropped across the corroded connection and the person measuring would read 12v even though there was a problem.

Joe did use both a test light and multimeter at various times, which required additional testing be done to eliminate the possible misinterpretation of results, but I think in the end we narrowed it down to the bad connection in the junction box. If you get some time to read over the thread, I think Joe and I would both value your opinion.

Don't worry I won't mention a word to Joe that you will buy lunch AND fix his light problem. I may take you up on the offer though the next time I need to crawl under the dash. I think the 9 hour drive is more favourable than crawiling under that dash again.

[six50joe]

I think I owe you both lunch at Wendy's, plus some beers. DD, I'll bet you'd probably spend 5 minutes in our Rav and have the problem solved. In the end, I wouldn't be surprised if the real problem is something really easy to fix, like the accessory tip in the cigarette lighter was for the radio short.

If I knew which connector to disconnect while getting upside down and contorting my fingers I'd probably go for it. I have fresh memories this year of crimping a wire and causing a short that ruined the optical drive in my Mac while struggling to install it in it's bay. Consequences of damaging something unrelated to the personal lights are enough to scare me from trying.

Tomorrow I'm going to see if it would be easy enough to put fuse taps in the actual DOME fuse in the box to the right of the engine and wire up to the BLU/YELs in the windshield column. If I'm able to confirm the BLU/YELs as Rick described, and snake the wires through (I'm assuming I should do two wires, one for each BLU/YEL so the load is correct?), I'll go for it.

[Rickl]

Originally Posted by six50joe

Tomorrow I'm going to see if it would be easy enough to put fuse taps in the actual DOME fuse in the box to the right of the engine and wire up to the BLU/YELs in the windshield column. If I'm able to confirm the BLU/YELs as Rick described, and snake the wires through (I'm assuming I should do two wires, one for each BLU/YEL so the load is correct?), I'll go for it.

You only need one wire from the fuse, and then connect the new wire to the 2 blue/yellow wires that head towards the roof. Tape over the ends that head towards the fuse panel in case the bad connection clears itself over time and once again makes contact.

Originally Posted by Rickl

You could temporarily touch this new wire to a 12V source like the cigar lighter to prove it will work before spending any time or money to purchase the fuse taps.

Making the temporary test connection means no fishing wires either until you know it will be worth your while. All the work can be done without leaving the drivers seat.

[Dr. Dyno]

Originally Posted by six50joe

Tomorrow I'm going to see if it would be easy enough to put fuse taps in the actual DOME fuse in the box to the right of the engine and wire up to the BLU/YELs in the windshield column. If I'm able to confirm the BLU/YELs as Rick described, and snake the wires through (I'm assuming I should do two wires, one for each BLU/YEL so the load is correct?), I'll go for it.

Again I haven't reviewed all the testing, but it does sound like a disconnect (an open circuit not a short) has developed somewhere in a connector or harness. And bypassing it (with one wire) is sometimes preferable to tearing everything apart and possibly causing other problems. And as long as you connect the BLU/YEL at the fuse to the BLU/YEL under the dash you'll be good. Pull the DOME fuse before starting. The only thing different I might suggest is not cutting the BLU/YEL existing wire since you don't know where else another open might develop. Good luck!

[Rickl]

Also, if you are not familiar with fuse taps (and there are many styles and sizes), make sure you connect the "tap" to the load side of the fuse and not the supply side.

[Dr. Dyno]

Originally Posted by Rickl

Also, if you are not familiar with fuse taps (and there are many styles and sizes), make sure you connect the "tap" to the load side of the fuse and not the supply side.

... meaning, just to be sure, it will be dead with the fuse pulled.

[six50joe]

I thought I had an 'aha' moment yesterday and that my next post would be one of triumph. Sadly, it isn't Before trying the hack, I tried spraying some electrical components cleaner onto the J/B and harness connectors in hope that maybe it would penetrate a little and find the corrosion that Rick had been referring to. (I had the battery disconnected of course while doing so). I also did this on the J/B to the front left of the driver's side door (where the turn signal plug is). Before replacing the panel for that J/B a blue harness connector caught my eye because it had 2 BLU/YELs coming from it (in the attached picture). I didn't have the schematics handy yesterday but thought it was too significant a coincidence because it was also one of the connectors that was wet before I fixed (hopefully) the Leaking when it rains issue.
Finally, when I disconnected the harness, I did in fact see signs of corrosion on the individual connectors. I figured that just had to be it. I sprayed it real good with the cleaner (but did not phyiscally clean the connectors yet as I didn't have anything to fit into the little square holes to clean with).
I waited a couple of hours for the cleaner to completely dry, reconnected the harness, then the battery. Nothing Either that wasn't it, or (I would hope) the connectors need to be physically cleaned with something. No flickering of the personal light bulbs or weak light, still dead as has been.
I didn't yet attempt any part of the hack (nor did I do the BLU/YEL confirmation test yet). When I opened the hood I didn't see any easily reachable grommet that I could feed a wire through. The ones that were easily reachable and visible were pretty tightly in place and I don't know if they come out on the inside of the firewall in a place I can reach.
Any thoughts on that connector or wiring if the hack is still the way to go?
DD, scheduling that trip out to Wendy's is starting to look very appealing

[Dr. Dyno]

Hey, if you found any corrosion that's progress! And you have the connector in hand. I'd try hooking the battery back up (yes that's safe) and turning the lights on. Then watch them as you connect/disconnect those plugs. If the lights do anything you've localized it and only have to physically clean the pins. That can be done by removing them from the sockets or you could run a bypass wire around them right there.
BTW, what's the pink snap-on connector on the left side of your picture?

FYI, those electrical sprays sometimes work for low power electronic circuits but not often for circuits carrying almost an amp.