Toyota Land Cruisers Are Waking Up Neighborhoods In The Middle Of The Night Due To A Ridiculous Electrical Problem

The 100 Series Land Cruiser is plagued with a poorly designed electrical system that wakes up neighborhoods in the middle of the night.

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Art by Jason Torchinsky, background by a famous painter whom you should all know.
Art by Jason Torchinsky, background by a famous painter whom you should all know.
Image: David Tracy

Not the Lexus LX 470. Of all cars, not the Lexus! I bought the Fancy Toyota Land Cruiser to act as a refuge from my AMC-era Jeeps’ frequent maladies, and for six months, the Toyota has lived up to its reputation — it has been flawless. But then Friday night at 3 A.M., the most annoying vehicular issue I’d ever experienced of befell me.

“BEEEEEEEEEPPPPPPPPPPPPPPP!!!!”

I sprang up from my bed instantly, wondering what all the fuss was about. It was 3 A.M., and I had been looking forward to catching some Zs, as I had lots of wrenching to do on Saturday (I swapped a steering box on a Jeep XJ, for those of you curious).

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An excruciatingly loud horn-sound blared outside. It could have been a siren. It could have been a car that had crashed near my house (I live on a main road). It could have been a jackass drunk driver or some disgruntled Jeep Compass fan trying to anger me.

There were lots of plausible reasons why a loud horn might be sounding outside my house, and yet, oddly, even at 3 A.M. and even when I was just barely awake, the first thought that came to my mind was: “Okay, which shitty car of mine is going ape-shit?”

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That’s where I’m at in life. It’s not good.

Anyway, here’s what I saw when I got outside:

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The Lexus’s horn is loud. Like, ridiculously loud. Since I’d recently installed a new battery into my key fob, I figured maybe the panic button had something to do with the ghost leaning on my steering wheel’s horn button. Unfortunately, pressing the panic button just activated a different set of horns. How many horns does the Lexus LX470 have?!

I resorted to pulling the battery cable, since I didn’t have time for this; I was tired. The following morning, I reinstalled the cable, and everything was fine for a few hours until it was not. I then yanked the cable, and that’s the current state of affairs.

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Noticing that the driver’s side floorboard had become a bathtub, I figured my problem was related to some sort of electrical short. I conducted a Google search, and learned that this phantom horn was a common problem with 100 Series Toyota Land Cruisers, and it tends to arise at the most unfortunate time: the middle of the night.

Here’s one forum-user’s account of his unwanted 3 A.M. wake-up call:

We had a large storm cell too through last night in Texas. Around 3:00am I was awoken by not thunder, but a horn blaring intermittently outside the house.

By the time I got dressed it was stuck on. I had to scramble to find tools and disconnect the battery while being half asleep.

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Here’s another story of a poor 100 Series Land Cruiser owner dealing with horn problems at 3 A.M.:

My son has a 2000 LC, during the night at 3am the horn came on, no blinking lights etc. He then started it and drove around the block hoping the thing would turn off. It did not. But when he turned off the truck the horn did stop. Today he just tried to start the truck and nothing happened.

I am assuming that turning the truck on and off reset the horn/relay etc.

This person got their wake-up call at 4 A.M.:

When I bought my ‘99, the horn fuse was missing. I replaced it. All was well. Last night (4am) the horn went off. The 100 was parked and locked. I couldn’t see the fuse diagram, and had to pull the wires off the horns to quiet the neighbourhood down. Seems weird it would just go off on its own while not moving or running?

My wife was in bed with me, so maybe it was telling me to GET a girlfriend?

This poor bastard got to listen to a loud horn at 5 A.M.:

I recently repaired a broken connection to my horn. After putting the horn relay back in, horn worked properly.

The other day, my son borrowed the vehicle and at 5:00am, the horn came on and wouldn’t stop. No one had gone near the Cruiser. He finally disconnected the battery. Later, he removed the horn.

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And here’s a 1 A.M. incident:

Fast forward 3 wks. About 1:00 this AM, I wake up to a blaring horn. It was mine. Not the alarm, just constant. Hitting lock/unlock/panic didn’t help, so I popped the hood and pulled the relay. I tried replacing the relay a couple times before work today, and the horn would start firing again, on its own, after a few seconds.

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What the hell is going on with these late-night Land Cruiser 100 Series horn incidents?

Well, a bit of research leads me to believe that the problem is caused by water intrusion into the driver’s side footwell area, where a large fuse panel (see image above from above IH8mud forum user ETXLX450F) sits upright on the left side against the vehicle’s sheetmetal. As I understand, on the back of that panel is a horn relay, which water has a tendency to ground out, causing the horn to go nuts.

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Image for article titled Toyota Land Cruisers Are Waking Up Neighborhoods In The Middle Of The Night Due To A Ridiculous Electrical Problem
Image: David Tracy

Speaking of nuts, a close inspection of my Lexus’s underhood area revealed a large squirrel nest:

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Image for article titled Toyota Land Cruisers Are Waking Up Neighborhoods In The Middle Of The Night Due To A Ridiculous Electrical Problem
Image: David Tracy

This could contribute to water getting into my cabin, though per the forums, the primary causes for the horn issue are a bad windshield seal or a clogged sunroof drain. I’ve been parking under a pine tree, so I wouldn’t be surprised if the answer were the latter. Too bad my sunroof doesn’t open.

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I’ll do some testing with a hose to figure out the source of my leak. As for the horn relay moisture, I’m hoping that just goes away. A number of forum members say their electronics have dried out, and they’ve never had an issue since. Hopefully that’s the case for me.

Either way, it’s an absurd failure that, due to rain’s propensity to fall at night when it’s cool (density increases at temperature drops), tends to happen at the worst possible time.