2005 Land Cruiser 100 Series Electrical Issue... Any Advice??

[SLO4RNR]

Here's the issues I'm having...

We've owned this LC since January 2025 (so semi-new to us) and has 80,500 miles. Everything has worked fine since we bought it and have had no issues.

Two weekends ago we were driving back from Great Sand Dunes NP. We use the Tape Deck with aux cord to listen to music from my phone. We noticed the tape deck randomly clicking then resetting, like it was powering off then restarting. Thought, hmm that was weird. But then it worked for the rest of the 3 hour ride home. The following weekend we noticed that the clock was resetting to 1:00 after starting the engine, also weird. A couple days later my wife ran an errand, came back to the vehicle and there was no electrical power at all, similar to the battery being disconnected. We have a quick disconnect on the negative terminal. I had her flip that up to disconnect and then push it down to reconnect. Electrical power was then restored and she was able to start it and make it home. When I got home, the LC again had no electrical power. I flipped the negative quick disconnect on the battery and reconnected and the power was restored. I checked all the terminals, everything was tight, no corrosion. Tested the volts with a multimeter and was getting 12.36v. I started the engine and tested the volts at the battery again and was getting about 14.2v with it running. I removed the battery and took it into the auto parts store to test. The battery tested good, but they said the volts was at 12.2v. and recommended charging it. So I got home, reinstalled the battery, cleaned all the terminals, reconnected the battery and put my NoCo trickle charger on the battery overnight. Checked in the morning with the multimeter, and it tested at 12.6v. Also checked both sides of the negative terminal quick disconnect to rule that out, getting 12.6v at each side. That connection is super snug and getting the same volt reading on both sides, so ruling that out. The next day my wife drove the car and everything worked fine, no issues. Today when she drove, the the tape deck thing started happening, then she got back into the garage. When she turned the engine off, there was again no electrical power (no dome lights, power locks not working.... She got out by manually unlocking. 10 mins later she went back to the LC to get some things out of the back, and when she opened the rear hatch the dome lights were working (she didn't do a reset on the -neg cable on the battery this time). Ugh...

Has anyone experienced anything similar? Any advice on what to check next would be greatly appreciated! I'm going to go home at lunch and try to diagnose for the rest of the day. I'll test to see what the volts are reading at the battery is now (48 hours after reinstalling and driving)

Any fuses to check? Ground cables? Alternator? Is it something to do with key transponder perhaps?? Idk, i'm at a loss right now. Any advice or recommendations would be greatly appreciated. Just stumped by the complete electrical loss after turning off the engine...

Cheers!

-Brian

 

[J1000]

First thing I suspect is the battery disconnect. It sounds like it has an intermittent connection. When the truck is running it's running off the alternator only which would cause voltage fluctuations as the engine revs up and down. That would also explain why the battery was only 12.2v, because it wasn't being charged, or only partially charged after the engine is running. What sort of disconnect is it? Cheap chinesium or name brand? I think it would be worth driving the vehicle with the disconnect removed for a week or so and see if the problems comes back.

Sure it works when you reset the disconnect but then when you drive and there are vibrations and heating and cooling the contacts could be separating.

 

[SLO4RNR]

Ok sounds good. I’ll ditch the quick disconnect and report back.

It was installed by the previous owner.

 

[wesintl]

I have similar issue on my 100. The negative terminal clamp is as tight as it can go but it's not super tight on terminal. I'll get a no start here and there, not often and i know what it is so it doesn't bother me. HTH

 

[DaveInDenver]

I wouldn't rule out that the battery is bad either just yet.

There are a couple of right ways to check them. You charge it fully and let it sit before measuring it. This is usually a few hours. You have to let the battery settle because when you take it off the charger it will have what's called a surface charge on the plates. It's literally what it sounds like, a temporary elevated voltage. By letting it sit this charge dissipates into the chemistry and you get closer to the real level.

The best way to test is using a load tester. That's what the auto store should have done if they had an actual device. What they do is put a big resistor on the battery and see how far the voltage drops under load. That it showed 12.2V here would indicate to me it's questionable. Whether it's aged or just low on charge you'd have to eliminate by doing an overnight charge first of course. The proper battery tester will allow you dial the actual load and see resulting voltage. A big truck battery should hold up to a load of couple hundred amps without problem while a car sized might do significantly less. In any case, the tester will give you a load-vs-voltage indication you can use to determine how aged the battery is since with each use they lose a little capacity.

You can simulate a load test by watching voltage during starting. A good battery will normally droop to perhaps 11V or so while starting. If it's lower than this you need to worry, either you're not fully charging or it's bad. A battery will fail to start a car when it droops to around 10V or so. The technical term for this is minimum cranking voltage.

 

[SLO4RNR]

The battery is one year old, has 10/24 sticker on it.

So I took off the negative terminal quick disconnect that the previous owner installed. I then noticed it had a conical tapered shape to it. Maybe it wasn’t getting a full connection all the way around the terminal, even though it was tight?

I took this off and reinstalled the negative clamp back on the battery.

Started the engine and tested the volts off the battery again. 14.05v at idle. Then I turned on the heater fan to high, turned on high beams, seat heaters, radio… 13.72v under load. Seems to be n normal range.

I drove around for an awhile and made a few stops turning the engine off and then back on. I couldn’t get the problem to replicate. The clock didn’t reset. The battery was at 12.56v when I turned the engine off. I’ll let it sit for the next few hours and see what the multimeter reads the volts at on the battery

 

[Hulk]

Sounds encouraging. Hopefully you cured the problem.

 

[Hulk]

Also, how on earth did you find a 20-year-old Land Cruiser with only 80,000 miles?

 

[DaveInDenver]

So I took off the negative terminal quick disconnect that the previous owner installed. I then noticed it had a conical tapered shape to it. Maybe it wasn’t getting a full connection all the way around the terminal, even though it was tight?

SAE type battery terminals are supposed to be tapered. The specified angle is 1:9 inch:inch, which works out to ~3.2° per side or ~6.3° included although it's not like you can really check that easily if you're not a machinist.

That disconnect looks to have a taper that becomes a flat, so I'm wondering if the terminal was pushed or hammered down so far to hit the parallel part of the cylinder, which would have left gaps.

The key is not to crank the clamp bolt down to the point of distorting them. That could explain it if the connection has gaps or someone's cranked them so tight that the clamps have stretched or even fractured. If you use good terminals (such as Toyota did) on a properly made battery you don't need a lot of torque on the bolt for a snug fit.

 

[Notyourmomslx450]

Also, how on earth did you find a 20-year-old Land Cruiser with only 80,000 miles?

Grandma owned... only driven to bingo, the store and church

 

[SLO4RNR]

Also, how on earth did you find a 20-year-old Land Cruiser with only 80,000 miles?

Definitely a unicorn find, so i jumped on it! Bought it from a good friend of mine for my wife. Might be for sale soon tho... wife wants a new Grand Highlander.

 

[SLO4RNR]

SAE type battery terminals are supposed to be tapered. The specified angle is 1:9 inch:inch, which works out to ~3.2° per side or ~6.3° included although it's not like you can really check that easily if you're not a machinist.

That disconnect looks to have a taper that becomes a flat, so I'm wondering if the terminal was pushed or hammered down so far to hit the parallel part of the cylinder, which would have left gaps.

The key is not to crank the clamp bolt down to the point of distorting them. That could explain it if the connection has gaps or someone's cranked them so tight that the clamps have stretched or even fractured. If you use good terminals (such as Toyota did) on a properly made battery you don't need a lot of torque on the bolt for a snug fit.

I did not know, thanks for sharing the info!

 

[Inukshuk]

I do not suspect the disconnect or its taper. I agree removing the disconnect is a proper diagnostic step.
"The battery tested good, but they said the volts was at 12.2v. and recommended charging it."
12.2 after taking it from the truck is not, in my opinion based in experience, good at all. Resting state voltage of good car battery should be 12.6-12.8

Its surprising what weird things a bad battery can do. BTDT For example, if the plates are being bridged by moving internal debris you get all sort of wilderness. "The battery is one year old, has 10/24 sticker on it." Warranty that thing!

Also, after you get a warranty replacement battery, consider: Fuses can be not-blown and do all sort of weird things. Are radio, dome, and other visible things acting up on the same fuse as the start functions/immobilizer circuit? Its also cheap to swap in some new fuses. I once had all sort of weird gremlins in my 80 and a fresh set of Buss blade fuses cured it. Finally, and after battery and fuses, the 100 engine fuse block has a long history of internal invisible failures. Lots about that on MUD.

 

[Lastresort576]

Definitely a unicorn find, so i jumped on it! Bought it from a good friend of mine for my wife. Might be for sale soon tho... wife wants a new Grand Highlander.

fwiw, I just picked up my wife a '26 awd hybrid grand highlander xle. (shes coming from a '21 awd hybrid highlander xle). The grand is really nice. Comfortable, handles well, runs quieter, gets up to speed nearly effortlessly, and its rated for something like 36mpg hwy or combined which is pretty freakin good for a 6,250# vehicle I feel. OTD cost was about $55k.

 

[Hulk]

I think my ‘02 100-series gets 10-11 mpg. 36 mpg sounds like nirvana.

 

[60wag]

fwiw, I just picked up my wife a '26 awd hybrid grand highlander xle. (shes coming from a '21 awd hybrid highlander xle). The grand is really nice. Comfortable, handles well, runs quieter, gets up to speed nearly effortlessly, and its rated for something like 36mpg hwy or combined which is pretty freakin good for a 6,250# vehicle I feel. OTD cost was about $55k.

Highlander should be 4600 lb curb weight, 6140 lb gross weight, unless you have a lot of armor bolted to it

 

[Lastresort576]

Highlander should be 4600 lb curb weight, 6140 lb gross weight, unless you have a lot of armor bolted to it

You’re right I stand corrected. Could have sworn I read the higher weight at the dealer.