Need help diagnosing odd behavior (1 Viewer)

[Slashzero]

Hi all,

2003 LC, 205k.

The last 5k miles or so, whenever I’m at a stop, in drive, with the breaks on, the truck’s engine tone lowers, and I feel slight vibration. If I put it in neutral, the vibration goes away, and RPM/engine tone gets back to normal.

Symptoms

• Just a few days ago I also noticed then when I’m at a stop and I’m drive, my battery voltage is dropping halfway to 9, until I hit the accelerator when it goes back up to 14. If I pop it in neutral it moves up very slightly. If I put the parking break on and release the brake it goes up very slightly again. When I start moving again it goes back to 14.
• It has no issues starting whatsoever, however a few weeks back I tried to use my truck to jump start another car and it just couldn’t do it. I had to use a jumper pack to start the other car instead. Could it be the alternator? Belts?
• A few months ago I took it to a mechanic down the street and he said everything seemed normal, and the only thing he could think of is maybe I needed new motor mounts.

Can anyone give me a few ideas of where to look what to check? I have an estimate from a year is so ago from a dealership where they said I needed $13,000 worth of maintenance/work. I should go look through that estimate to see if anything jumps out. I think I just remember the breather was clogged on the transmission. Completely forgot about that.

 

[yukon]

Could be a dying alternator, I would test the voltage at the battery at idle. Shouldn't fluctuate much between idle and revved.

If you don't have a volt meter, just replace/rebuild alternator. Dropping voltage at idle is no good

 

[Ayune]

First check your battery health. Have it analyzed or swap with a known-good one to see if the behavior changes.

More likely your alternator brushes may need a refresh. ~$20 part I believe but getting to them is tricky. No need to replace the whole alternator (mostly mechanical) if only the electrical brushes are bad.

If I put the parking break on and release the brake it goes up very slightly again.

This is from your brake lights. When they turn off there’s less electrical load on the alternator.

For fun, try turning on everything while at idle: high beams, blower fan, seat heaters, wipers, fog lights, etc. & watch your voltage plummet.

I have an estimate from a year is so ago from a dealership where they said I needed $13,000 worth of maintenance/work.

I think we’ve all gotten a quote like that from a stealership. Ignore the numbers and use it as maybe a roadmap for DIY work with help from ‘Mud.

I think I just remember the breather was clogged on the transmission. Completely forgot about that.

How the hell do they diagnose that? Did they pull off the tube and blow through it? Jeez. How much did they want to “fix” the “problem”? (Nothing to do with your issue, BTW.)

 

[kruisinkid]

battery or alternator. take it to a big box place and have them load test the battery and check the alt. the voltmeter on the dash, i believe, is showing output voltage of the alt, not battery voltage. so if its diving that much, thats not good at all.

 

[2001LC]

Try good tune up first.

Search D vibration.

Look also in my master link for better understanding of PM.

 

[AlpineAccess]

Grab multimeter.

With car off, after sitting overnight, check voltage on batt. Should be greater than 12.3 volts.

Start car. Check voltage at positive terminal and put ground prong on the chassis/motor. Should be 14.3 (charging rate) as alternator tops up battery. If it holds nice and steady that's good. Have someone turn on a bunch of a accessories while you watch the multimeter, it should dip and recover to 14.3. Check that the voltage is reading the same on the block, chassis, and accessories.
If it's reading different voltage numbers on different parts of the vehicle (even .1 volt) check and clean your grounding cables.

Let us know if it's charging more or less than 14.3. Can learn a lot from the alternator output number.

If charging really high at startup and then levels off to 14.3 after a few minutes your battery is needing to be topped up. Batt is probably bad.

If it's holding really high charging voltage even after running a few minutes, again your batt might be bad, alt might have dead diodes, or voltage regulator might be bad (rare).

If voltage is fluctuating all over, fairly rapidly ( from 12 to 14 and then 13, then 15, etc). Probably bad brushes or again, diodes.

Another thing to check: if someone installed a replacement alternator and used the wrong gauge wire to ground or connect to bus panel. This acts as a resistor and causes overcharging. I've found this is more common with alternator replacements than we might hope. I've even found shops have used spark plug cables. Frustrating. Have not found this on a land cruiser but a shop did this on a Dodge Dakota my wife owned way back and I screwed around with it for longer than I'd like to admit.

Also, check if the battery is swelling.

Apologies for the novel.

 

[nukegoat]

I'd replace the battery.

 

[Slashzero]

Thank you for all the replies! I will go through this “checklist” tomorrow, or Tuesday and post back what I find.

I have a battery load tester, and a few different charging / jump start units. One will let me trickle charge, which I would try, but if it’s the alternator I’m just kicking the can down the road and risk power failure while driving at any point. I will likely try to load test the battery before anything else.

the vibration thing really bothers me because the truck was smooth as silk when I first got it. I really need to figure that one out.

 

[Slashzero]

Type a good tune up first.

Search D vibration.

Look also in my master link for better understanding of PM.

That is a good idea! I will check out your link too.

aha! I was thinking the vibration could be the u joints / drive shaft. Back when I got that $13,000 estimate, one of the items was the front drive shaft u-joints should be replaced. I had the mechanic down the street look at things back then and he said nothing was wrong with the u joints.

I ordered u joints and a u joint press back then anyway, as a precaution, with the intent to change them myself at some point.

When I recently took it to the same mechanic for vibration he said the u joints were fine, didn’t see anything wrong or feel any vibration, and that the only thing he could think was maybe I needed new motor mounts.

I should just get under the truck and see if there is any play in the drive shaft.

 

[Slashzero]

How the hell do they diagnose that? Did they pull off the tube and blow through it? Jeez. How much did they want to “fix” the “problem”? (Nothing to do with your issue, BTW.)

No idea. This dealership has a scumbag as the service manager. He said my truck should never have passed inspection and the mechanic who gave me a sticker should have their license revoked.

 

[kruisinkid]

do the RPMs drop as well? what was never mentioned in that endless rabbit hole of a thread was that the truck was dropping down to 600 which is too low per the FSM. should be in the 650-700 fully warmed up. sure a tune up cant hurt. 44k, fuel filter, new belts, make sure all pulleys are smooth and turn freely. if all vac hoses are original you should check them all. im willing to bet the ends are all cracking. PCV valve and hose. oil cap gasket (yes thats a thing), fuel cap. all very easy stuff to check and replace. plugs/coils. but i would make sure your battery's cells check out as good.

 

[kruisinkid]

No idea. This dealership has a scumbag as the service manager. He said my truck should never have passed inspection and the mechanic who gave me a sticker should have their license revoked.

that dipsh!t is probably single-handedly keeping the service dept afloat with fear mongering and upselling.

 

[saucebox]

No idea. This dealership has a scumbag as the service manager. He said my truck should never have passed inspection and the mechanic who gave me a sticker should have their license revoked.

Entirely possible his stunted twin works at one of the local dealerships here.

 

[Slashzero]

that dipsh!t is probably single-handedly keeping the service dept afloat with fear mongering and upselling.

Yup. I never went back there again. There is a mechanic who was recommended to me here on these forums and for anything serious I take my truck there (they regularly work on Land Cruisers.). It’s a few towns over though, so I have a mechanic down the street I take it to for minor stuff. The downside of the one down the street is most of the time he just tells me “there’s nothing wrong.”

I think I might just schedule some time with the good LC mechanic at this point, as it’s winter and I don’t have time to do the work myself, and I’d have to do the work in my driveway, with snow.

 

[Slashzero]

do the RPMs drop as well? what was never mentioned in that endless rabbit hole of a thread was that the truck was dropping down to 600 which is too low per the FSM. should be in the 650-700 fully warmed up. sure a tune up cant hurt. 44k, fuel filter, new belts, make sure all pulleys are smooth and turn freely. if all vac hoses are original you should check them all. im willing to bet the ends are all cracking. PCV valve and hose. oil cap gasket (yes thats a thing), fuel cap. all very easy stuff to check and replace. plugs/coils. but i would make sure your battery's cells check out as good.

Great question. Based on the change in pitch, I would say yes, but I’ve never looked at the gage (which is dumb). I will check the gage tomorrow morning.

 

[AlpineAccess]

Once you check battery/alternator/regulator off the list - should take less than 5 min to troubleshoot, I would turn to vacuum hoses.

Very small leaks can cause rough idle without codes thrown. Bigger vac leaks will cause some surging.

On the trend of other cheap items to go over; MAF sensor cleaning, check/replace air filter, spark plugs...

 

[Slashzero]

Good morning! Thanks for all the replies.
There is freezing rain this morning so I’m not going to get under the hood and check the voltages, but I was able to check the RPM.

In Park or Neutral, with Brake applied, RPM is hovering between 600-800, closer to 600.

When I pop it in drive with the brake applied it drops to below 600, closer to 600

I also have video where you can hear the change in pitch if anyone thinks it would help.

I called a few mechanics asking about vibration and U-joints. One said “no way it would be the u-joints because the shaft isn’t spinning at a stop.”

Both garages I spoke to mentioned it’s more likely the engine mounts and that I should bring it in to get checked out.

Re: battery voltage: when brakes are applied in drive, and a whole bunch of accessories are on, it drops down to the first line below 14. Comes back up when I start moving. If I disable most accessories, it still drops but maybe only halfway to the first line. So I’m thinking new alternator. I will try to confirm by measuring voltages soon. I don’t want to risk load testing the battery and then having a dead battery.

 

[2001LC]

That is a good idea! I will check out your link too.

aha! I was thinking the vibration could be the u joints / drive shaft. Back when I got that $13,000 estimate, one of the items was the front drive shaft u-joints should be replaced. I had the mechanic down the street look at things back then and he said nothing was wrong with the u joints.

I ordered u joints and a u joint press back then anyway, as a precaution, with the intent to change them myself at some point.

When I recently took it to the same mechanic for vibration he said the u joints were fine, didn’t see anything wrong or feel any vibration, and that the only thing he could think was maybe I needed new motor mounts.

I should just get under the truck and see if there is any play in the drive shaft.

Post a picture of Dealer estimate for $13K.
My guess is they found many neglected items, that a minimally maintained 2003 with 205K would be in need of (base-lining).

Font drive shaft (AKA CV's). Spider joints (aka U-joints) of forward & aft propeller shafts (AKA drive shafts), slide yokes of propeller shafts, wheel bearings, tire balance, etc. Can all cause vibration when driving.

Provided you did not cross connect battery cables during jump. It's not likely you damaged the battery or alternator.
BTW: Always connect jumper cable, to a ground of vehicle and never directly on the negative battery post of battery. Or you may damage alternator, if you cross connect.

"D" vibration, is one well documented in mud. It's the one setting with foot on brake while in "D" (drive). New engine and transmission mounts can help. Some stick a rage between spare tire and frame. Others remove roof rack and or engine cover. But typically those are symptom. Cause is engine not running smoothly. Typically a tune-up will cure. The tune-up should start with disconnecting the battery and cleaning then greasing the post. Always disconnect negative post first and reattach last. If battery cables, post & battery are dirty looking. Than start by washing battery and area with baking soda and water solution.

Having the battery disconnected for 20 minutes or longer while doing the tune-up which includes cleaning the MAF sensor, resets the ECM. This is a must to get good results.

For the most parts, every 100 series I look at, can benefit from a tune up. Tune-up with spark plug replacement and at minimum a coil boot & seal kit. Also 3 or 4 vacuum lines are almost always in need of replacing. Air filters and good gas cap seal are a must.

 

[AlpineAccess]

Good morning! Thanks for all the replies.
There is freezing rain this morning so I’m not going to get under the hood and check the voltages, but I was able to check the RPM.

In Park or Neutral, with Brake applied, RPM is hovering between 600-800, closer to 600.
View attachment 2152555

When I pop it in drive with the brake applied it drops to below 600, closer to 600
View attachment 2152556

I also have video where you can hear the change in pitch if anyone thinks it would help.

I called a few mechanics asking about vibration and U-joints. One said “no way it would be the u-joints because the shaft isn’t spinning at a stop.”

Both garages I spoke to mentioned it’s more likely the engine mounts and that I should bring it in to get checked out.

Re: battery voltage: when brakes are applied in drive, and a whole bunch of accessories are on, it drops down to the first line below 14. Comes back up when I start moving. If I disable most accessories, it still drops but maybe only halfway to the first line. So I’m thinking new alternator. I will try to confirm by measuring voltages soon. I don’t want to risk load testing the battery and then having a dead battery.

Using that battery gauge in drive isn't producing a test that can be used to verify alternator performance.

You're driving rpms down via whatever issue you're having by engaging the trans and dropping revs to 600 rpm. Then demanding peak performance from the alternator, which it can't provide at low revs like that.

Your regulator may then lean on the battery to make up for the demand, which then causes more draw on alternator as it tries to charge battery and produce output at the low rpm.

It actually sounds like your alternator is working well based on the test you conducted, but we can't know for sure.

Hopefully this makes sense the way I've written it.

 

[Leandro]

I'd give the throttle body a good clean up and check vacuum hoses.
All the symptoms you're describing can be because the engine is almost stalling, because of the low RPM at idle. When you put it in Park, you are releasing the load to the engine, that's why the RPM go up a little.