Attack of the evil rodents... Need suggestions... Horn crazy. Short?

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Gotta get outta here...
Sep 20, 2003

did not drive the 100 for a few days. Goes there today. The door does not unlock with remote. OK. Get in. Not a light on the dash. Measure the battery voltage. 4V. Puzzled. Put a jump charger on it, immediately the horn starts bleeping (discontinuous sound, like blap blap blap etc). Disconnect right away. Look around. Rodent poop. Look some more, a bunch of insulation material in the V8 trough under the manifold. Big freaking nest. Yikes!

Thinking that the little bastid chewed on some wire and short circuited something. Can't see anything wrong with the wiring under the hood or in the footwells.

Anybody knows what the horn doing that number means? Where should I look first for chewed up wires?

Bummer... Like I needed this now...
Any chance that there is an (orphaned) aftermarket alarm tucked up under the dash somewhere?
Indeed there is an alarm of sorts, IIRC. The thought crossed my mind but it did not seem obvious that the alarm going off would be related to low voltage. Although that would be great if it's just that. Is that likely? But then again, the battery likely didn't just discharge suddenly by itself, probably, so there is likely a short someplace that did discharge the battery, I would think. Unless it's something odd like the lights stayed on and the evil rodents are just a coincidence. But I don't want to attempt to boost the battery until I'm sure or almost sure the wiring is OK. Don't need a fire now either.
One of ours had an aftermarket (dealer installed) alarm. The alarm did have an additional constant battery draw, compared to our other 100 series.

If the battery got too low, it would trigger the “thieves have disconnected, and reconnected the battery” logic, which would cause the alarm to flash lights and honk horn (really just click the relays) until the battery was completely dead (thanks you stupid alarm!)

Standard practice when this happened:

- disconnect wires to the two horns under hood

- connect battery charger

- put key in ignition, and turn to “on”

- stand on head and track down alarm “toggle switch”

- turn off ignition and remove keys

- let battery charger fully charge battery

- reconnect horns
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Good to know. Well, if the honking is just due to low then high voltage on the alarm that's easy to deal with. Except that gives no clue as to what happened, unfortunately. I was sort of hoping that it would point to where the problem is. Wishful thinking...

Maybe I should just put a power supply on the battery with a very low current limit, like much less than an amp, and see if there is any corresponding draw from the battery when I do that. . That might preclude a bad short and overheating and tell me if there is indeed a short or not.
Another option might be to disconnect the negative lead, and try to charge the battery while disconnected from the vehicle. If it’s been taken down to 4v, it may not take a full charge anymore.
Another option might be to disconnect the negative lead, and try to charge the battery while disconnected from the vehicle. If it’s been taken down to 4v, it may not take a full charge anymore.

yes, can do that, but the issue then will be that I'll have a lot of juice in the battery afterward, and if there is a short it may go bang when I reconnect the battery to the truck. When I first saw this nightmare, I measured the draw on the battery at 4V and it was only 0.1A or so, so not much, but that is of course a function of the voltage.

Use ignition key to unlock driver door will stop the honking.

To avoid honking, set the key to ON position in the ignition switch before connecting new battery or jump pack.

Good suggestions, thanks, but given the unknowns here I think I'd rather disconnect the horn for a bit than take a chance on having the ignition on when connecting the battery, that seems potentially iffy to me.

I do need to look more seriously at all the wiring before I do anything else much. Any wild guesses as to what wire is more accessible / enticing to critters and more likely to have caused the dramatic discharge?

I would normally hope the ugly critter got its brains zapped, but don't want to deal with a carcass in there either. I cleaned up the nest and left a light on all night under the hood to deter it from coming back tonight.... Sheesh...
Some random Toyota alarm system tips and rodent prevention.

A few years ago I purchased a 1999 Tacoma that came with a "US distributor installed" alarm system. I think it was an Audiovox system that "Gulf States Toyota" had installed before the trucks were sold new. One day the system started malfunctioning and left me stranded. The local dealer was great and showed me how to reset the system

They suggested taking the truck to a local vehicle alarm installer to have the system removed. Installation instructions were still available for that unit so removing it was easy. Should I have another aftermarket system that gives trouble, I will have it removed by an alarm installer.


I've experienced rodents chewing up knock sensors and injector harnesses. The rodent problem was made worse by the manufacturer using soy/biodegradable material in the wiring harness covers. I've learned through the years that rodents do not like to chew on F4 silicone (or similar) tape. I've rewrapped harnesses on cars/trucks using silicone tape and see rodents building nests by the wrapped wires and never touching them. As a matter of course, I rewrap the knock sensor and injector wiring harnesses with plastic conduit and F4 silicone tape when I do maintenance in those areas. This has been working for 11 years.
wait, are you telling me that those critters are not only evil but vegan as well....? :censor:

Update: Did the slow voltage increase while monitoring the current. No evidence of major short. So put a jump power supply on the battery, got the alarm to stop going crazy, and the engine started fine. And ran fine. So seems like we may be very lucky and the critter did not munch on the wiring after all. Hope so.

Still don't know what caused the battery to go dead. Gotta monitor that still.

Can't believe I half filled a 5 gallons bucket full of nesting material just from under the intake... Critter had it good under there.

And ironically, some years back I took off the beauty cover thinking that this would help prevent rodents from nesting under there.

Might want to look at yours...

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