Hey all

What started out as a once in a blue moon occurrence has now rapidly become a reliable and very annoying problem, arguably at the worst time it could have. Seemingly whenever it's warm outside - about 80 degrees and above - I randomly lose power to my gauge cluster in the middle of driving. Sometimes it's within 5 minutes, sometimes it's after half an hour, but either way there's no rhyme or reason for it. This means I not only lose my tach and speedo, but all window and HVAC functions as well while driving around in the sun

I've noticed sometimes shutting down and letting the car sit for a minute or two will restore it, but if that doesn't work I have to unplug/replug the dash to get power again. That seemingly works out every single time

I've checked every wire I can for splits or cracks and have tried double-checking any ground I come across but everything seems totally fine. All fuses are good too - some of which I even replaced just for the giggles to see if it would stop it from happening again but to no avail

Anybody have any ideas what could be causing it? Is my dash dying or something? I'm worried that if I replace it altogether then my odometer will change

Hmm that is odd, that it only happens above 80 degrees. That might lead me to a possible relay. Ambient when cooler then 80 might just be enough to keep the relay cool. Any hotter and the relay shuts off. But I could be wrong too. Have you checked the circuit opening relay? I believe it's the blue one in the fuse box under the hood.

I don't have a wiring diagram in front of me now, so I can't check common grounds and powers.

Any recent electrical work on that system on your rig?

Nothing recent, no; the most recent was trying to tap in my diff locker switch to the dash light, but it didn't work so I removed it, and that was back in the winter as well The relay makes a bit of sense, I believe you're right that it's in the engine bay so it could be getting pretty toasty. I might look into replacing it just to be safe and see any changes

Update: reconnected the dash before I went into work and it did the trick. Went out to my truck again on lunch and it's dead again Very strange, hasn't done that before. Usually once it's "fixed" it stays on for a week or so

Anybody know what relay these functions run through? I found it in a thread a few months ago but can't find that particular post anymore

I have included the overall wiring diagram for the 2000 3rd gen. Hopefully it will help you find your gremlins. :-) I am chasing a tail circuit gremlin myself but I need to get a Honda civic done and off my lift to get the 4 runner in the shop.. :-)

Attached Images

	Overall_EWD-2000.pdf (546.3 KB, 29 views)
	Overall_How_to_Read_EWD_2000.pdf (87.0 KB, 33 views)

Damn thought I was in the clear.... I swapped my tail relay and put a fresh 10 amp fuse in the gauge cluster spot and didn't have the problem for quite some time, only to try and start up my car after sitting in 100 degree sun all day and it all went blank again :/

You wouldn't happen to have a wiring diagram for the interior fuse box would you? If not it's no big deal

Besides the Overall EWD Everything else is individual circuits. I unfortunately, do not have a gauge diagram. :{

Anyone know where I can find the integration relay on a 2000? When I try and look it up I just find people saying it's under/hugging the interior fuse box, but all I see is one solid unit. Is it perhaps integrated to the fuse box instead of a separate part?

This is my experience with wiring on my 4runner.
I was having issues in the cluster with the Gear indicator being intermittent, the cruise stopped working and the reverse lights stopped working. We traced the bad wiring to the harness from the neutral safety switch wire loom running from the trans through the engine bay to the fuse box. We unwrapped all the tape around the harness and found a crap load of exposed wires from corrosion or heat exposure, we ended up replacing almost every wire in that loom by hand. So I'd started by unwrapping and seeing if you've got the same issue. Good luck.

The body ECU is the "integration relay" from what I can find (or has it built in to it...). U can remove and replace the Board but there are many different part numbers even between the same yrs from what I've found (I save the broads from the fuse blocks I save from wrecked 4runner's/Tacoma's. U have to remove the cover on the fuse Box/panel to get access it the unit.

Well that blows

Keep working on it Devbot. You get this issue fixed. If you need that part check with Josh Young PNW4RunnerConnection

Honestly I just might give up. I really don't have the motivation to deal with this car anymore and chase down a complex gremlin that may or may not require a shotgun approach to it. If there was a somewhat simple answer then maybe - but since i dont even know where to begin and there's not even a hint as to what it might be, I'm not really keen to tear apart my car to the bones, replace wires just for the problem to may or may not get fixed, tear it apart again, wire in more shit, etc. etc.

However while looking over that EWD and reading other forum posts, I did have an epiphany as to why I could never get my diff lock light to come on with my switch ages ago - I followed instructions for a '98 which has totally different wiring, meaning I wired up a pin that goes to nowhere. So its kinda nice to finally have an answer to that at least

This thread is surprisingly devoid of questions.
First what HVAC system is it, I assume the automatic digital one?
What exactly are you unplugging and plugging in again to make it work again?

If you're unplugging the gauge cluster is it possible that maybe the cluster itself has issues? We all know how bad Toyota did soldering on other stuff.

If you have the digital odometer, I think the milage is stored in the car, so you won't lose it by replacing it with another. It is legal to replace odometers even if it does change the milage, you have to write down the old milage and the new milage and disclose it.

There are at least 3 variations of gauge cluster, but I know for sure that anything with an analog odo will be completely different from a digital odo one. So anything relating to gauge cluster will be useless to you if it's pre-1999.

I know people have proposed the fuse box and relay and given some good reasoning, but have you tried checking if power is getting past that part when the problem occurs? It would suck to do all that work and realize that power was getting by these suspected parts all along.

Start from where you know power isn't getting, and check before every connector that it still has no power (by shoving T-pins down the back side of the plug along the metal pin or stabbing insulation). If you find power, work your way back up until you find the point that flow of power stops. This is how you should approach it.

Its the manual HVAC and digital odometer in question, I have a sport model not a limited. What I would unplug would be the entire gauge cluster itself; all 5 connectors

However the kicker is that since it's become more frequent I've found that "soft reboot" isn't exactly what's fixing it; it's letting out all the 100+ degree air and having the interior cool down a little that does it. What makes me think this is when I would come out and have no power off the bat, I would simply open the doors for a little while then try again and power would regain without fail. To boot there have been times I very quickly got the dash out and tried to unplug/re-plug it back in and nothing would change. So I assume that when the problem first started happening, in the 20-30 minutes it would take me to pull the dash out it would become cool enough inside the cab again to work, leading me to believe I was doing something when I actually wasnt

After studying diagrams for the past couple days I plan to poke around with a multimeter this weekend, if I'm able to catch it happening again. It's supposed to be pretty warm out again so I imagine it'll come back. Hopefully I can do it in that short time frame - according to the wiring diagram I found, power is sent to and from the body ecu from plugs located behind it and I have no idea how easy it is to remove/access a spot with the multimeter