My 4runner keeps ending up with a dead battery. Tested the battery, its good. Tested the charging system, its good. Took the battery out and hooked the battery cables to my charger with my multimeter in series. First I was drawing 4 amps with the truck off. I think I sorted that out to a loose wire in the main distribution harness. Not positive, but it has gone away. I'm still showing a ~.2 amp draw which seems high. I started pulling fuses. When I pull the fuse for head lights and horn in the under hood fuse panel the draw drops to .008 amps which seems much more reasonable. I've pulled every fuse, relay, and module and the only one that has any affect is the head light fuse. I've inspected the wiring and can't find any obvious shorts. I'm looking at the wiring diagram. The only thing that looks like it should have power with the truck off is the hazards. Has anyone run into something like this before?

 

Ya when I got my 85 4 yrs ago I had a problem like this. It turned out I didn't know about the ignition lock button so the power was still on aaaall the time. I bought new batteries and an alt. And it was a mystery until a friend mentioned "uhm. You didn't turn the truck off...."

 

I am not sure what you mean has power with the truck off??

Did you mean Hazard /Horn Fuse?? Both of these work like the should ??

Unless you have something really rare The Headlights and Horn are not on the same circuit but then who knows with the age of these vehicles.

Every thing that is not controlled by the ignition switch has system voltage.

Headlights, Brake lights, Horn, all those goodies.

All the connections clean and tight I have seen corrosion cause a drain like this.

 

Yes it is the hazard/horn fuse. I haven't checked but I'm fairly sure the horn and the brake lights don't work with the truck off. The hazards and head lights do.

I did make sure to verify the truck is off and the key is in the lock position.

 

Let's clarify. Only the horn/hazard fuse makes drain drop from 0.2 amp to 0.008, correct? Not the headlight fuse, correct?

They should. Wanna double-check? Also check your actual wiring versus schematic, in case someone hacked wiring??

Yes, they should.

Hazards and horns should work even with truck off. They take power from battery wire "A"- always connected to battery, regardless of ign switch position.

Brake lights should work even with truck off. they take power from Battery wire "C", always connected to battery, regardless of ign switch position.

If above any of above is not true, perhaps things are connected to the wrong fuses. Unplug fuses and make sure those connected to them per schematic do NOT work.

 

Is there an alarm pulling juice by any chance?

 

Possibility, IF drawing power from hazard/horn fuse. That's why P.O needs to verify actual wiring versus schematic.

 

Ahh yes...


I missed that in your post when I read it over initially.


I can't count the number of times I have fixed electrical problems in older vehicles by returning wiring to stock, then fixing whatever minor problem wasn't trouble shot correctly and was hacked around.


It has often amazed me how industriously some people work to avoid properly fixing a simple item.

 

NP


Amen to that! Returning to stock also facilitates others like us trying to help. It's hard to troubleshoot, not knowing if subject vehicle is stock or not.

O.P.,
Any update on what works and what does not work with ignition on and off?
With hazard/hon fuse in or out?

 

So the drain mysteriously went away. As nice as it is that the problem fixed it's self self healing problems have a way of reemerging at the worst times.

 

Hmmm... Don't think you're done, yet.

In earlier post...
Which wire are your referring to? This could be a wire that sends alternator power to battery to charge it. Got picture of the wire? Where it was loose?

What has gone away?

Then, And have you figured out if wiring is stock?

 

Wiring is stock, well mostly. I miss spoke/typed in the first post. It was the horn/hazard fuse.

The loose wire was the main feed into the underhood fuse box. I had to replace the main feed wire and I didn't get the whole assembly clicked back in after replacing the wire. It wasn't touching anything that I can see.

I've driven the truck to work for the last two days. Starts first time, every time. I even left the headlights on at work this morning. Still started like a champ. Something moved and I'm sure it will reemerge at some point, but I'm moving on to rebuilding my winch.