Fixed... Gauge, AC Compressor, and Alternator Regulator Failure

sam.basye

Member
On my way to work (3hr drive) for the week and 30 min into the drive the cluster info died and the AC quit. The AC controls blanked out and lights off.

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Just prior to this the air got warmer/more humid. This afternoon I heard a slight click like a bearing was starting to go bad and all the driving today has been with the AC on full cold (93° out). This drive it was set to 73°.
I pulled over into a gas station to check and found a fine plastic shaving stuff thrown out from I assume the bearing and a leak which I assume is green Freon from the bottom of what I assume is the AC compressor.

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AC compressor?

I then noticed the headlights wouldn’t come on and saw the voltage was 9.4v so that means the alternator stopped charging. It was around 14v earlier today. Is this a result of the AC compressor going and why would I lose all instrumentation and the alternator?
Belts are all fine and in tact.

Battery is now dead...

Thanks
 
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After further research, could a sudden alternator failure be the culprit? Once it failed it started shedding off the highest load (A/C) then the engine signals to the dash?

Car drove and ran fine after losing the dash instrumentation and A/C off of the remaining battery power.

There’s no reason an A/C compressor failure would keep the alternator from charging based on separate belts for the 3.4 charging, steering, and A/C, right?

The alternator is original with 307k miles, but has kept ~14 volts up until this happened (I checked the voltage earlier that day) so a complete failure seems kinda odd...

I did get to keep 3 flares from the officer that showed up after a volunteer fireman stopped to help and called the PD since it was next to the highway. [emoji51]
I also got to try out my portable road hazard thingy I found in the junk yard a while back. lol

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Are you sure the green stuff was not always there? It's possible the A/C compressor is dying but not dead, and the fail is due to low voltage. A/C can't kill an alt.Low voltage can kill A/C, at least temporarily.

At 9.4V, there are no expectations for behavior except bad. The A/C clutch won't hold, relays may open, stuff just doesn't work. There is no intelligent signalling and load shedding going on.

Get yourself a healthy battery/charging system again, and then see what else is going on. First, charge and then load test the battery. Always rule out a bad battery first in these situations. You will save a lot of time and headache. THEN see what the alternator is putting out...although it does sound like it's a fail. Recognize that the factory Densos are close to bulletproof if not immersed or filled with mud, and wiring fails, especially around the plug, are common.

Troubleshoot this, don't guess. If it's really the alt...it's usually better to rebuild than buy a reman. A puppy dies every time someone turns in a factory Denso as core on a crap-o reman. If you need to get going, eat the core charge, then rebuild the Denso so it is ready when the crap-o reman fails. It won't be long.
 
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Are you sure the green stuff was not always there? It's possible the A/C compressor is dying but not dead, and the fail is due to low voltage. A/C can't kill an alt.Low voltage can kill A/C, at least temporarily.

At 9.4V, there are no expectations for behavior except bad. The A/C clutch won't hold, relays may open, stuff just doesn't work. There is no intelligent signalling and load shedding going on.

Get yourself a healthy battery/charging system again, and then see what else is going on. First, charge and then load test the battery. Always rule out a bad battery first in these situations. You will save a lot of time and headache. THEN see what the alternator is putting out...although it does sound like it's a fail. Recognize that the factory Densos are close to bulletproof if not immersed or filled with mud, and wiring fails, especially around the plug, are common.

Troubleshoot this, don't guess. If it's really the alt...it's usually better to rebuild than buy a reman. A puppy dies every time someone turns in a factory Denso as core on a crap-o reman. If you need to get going, eat the core charge, then rebuild the Denso so it is ready when the crap-o reman fails. It won't be long.



Thanks, as far as the green stuff, chances are that it’s probably always been there.

I just had the wife go out and turn the key after it has been trickle charging over night to see if the gas needle went up or the odometer came back. Showed 12v, but nothing. She cranked it and it started, but still no change and voltage didn’t increase then started to slowly drop.
Shouldn’t the instrumentation at least come back?
I have an obd2 reader and it was getting a signal for the tach last night after the issue started.

The battery is definitely due for a replacement, but wouldn’t a functioning alternator be sufficient to keep the vehicle fully powered at highway speeds unless the alternator itself fails?

Battery, Alternator, and relays seem like the most likely culprits at this point. I checked fuses last night, but they looked intact.
 
If your battery has a bad cell it could be bad enough to where the alternator couldn't keep up. A functioning battery is just as important as a functioning alternator in a vehicle's electrical system. With that being said, I would lean more towards your alternator is the issue.
 
If your battery has a bad cell it could be bad enough to where the alternator couldn't keep up. A functioning battery is just as important as a functioning alternator in a vehicle's electrical system. With that being said, I would lean more towards your alternator is the issue.



Thanks!
Looks like battery will be the first thing regardless and then the alternator. followed by crying, then cursing if that doesn’t do it. [emoji23]

Optimistically those two will fix it all, but realistically I have my doubts the A/C and cluster will come back without a lot of probing..[emoji1694]

Could whatever caused the issue have fried a relay, or multiple relays? Both the instrumentation and HVAC quit at the exact same time. Ironically the same time I was downloading a gps speed app to see if my 33’s rolled faster/slower than the speedometer...
 
What previous folks have said. In addition, get an alternator brush assembly for $20. Extremely easy to replace, and the cause of many similar headaches.
 
Help... AC Compressor Failed and Alternator Stopped Charging

What previous folks have said. In addition, get an alternator brush assembly for $20. Extremely easy to replace, and the cause of many similar headaches.



Thanks for the suggestion. I’ll look into getting the brush assembly.

Anyone else think the brushes will be sufficient or is the alternator completely toast?
 
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Thanks for the suggestion. I’ll look into getting the brush assembly.

Anyone else think the brushes will be sufficient or is the alternator completely toast?

Yes, I helped my dad rebuild his alternator on his 01 with 320,000. The brushes were $6 at oriellys and they're still working now with 20,000 more miles on them.
 
Thanks for the suggestion. I’ll look into getting the brush assembly.

Anyone else think the brushes will be sufficient or is the alternator completely toast?

There's a good chance new brushes will fix your problem.

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Yes, I helped my dad rebuild his alternator on his 01 with 320,000. The brushes were $6 at oriellys and they're still working now with 20,000 more miles on them.



Great info, thanks!


There's a good chance new brushes will fix your problem.



<iframe width="560" height="315" src="https://www.youtube.com/embed/71_kBhg6_-A" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>


Late to the party, Tim. I already watched your video this afternoon [emoji16]
Thank you for all your videos. They have been an invaluable resource for maintaining, upgrading, and keeping her running strong at 307k! [emoji1377]
 
I strongly suggest you have the alternator tested off the truck before you replace or even service it, and that you carefully inspect your alt. wiring for damage. I am concerned you have not mentioned ever getting an alt. warning light, which I would have expected with a simple brush failure.

It could be that the bad battery coupled with a failing alt. caused this, but I still think it is important to verify that wiring. At the plug, you should get battery voltage on the white and red-blue wires (ignition on, engine off) and the alt dash light should come on if you ground the yellow-green. Also verify battery voltage at the big wire, and that its connection is solid.

Wiring issues are cheap fixes, and you feel really stupid when your new alt. does not fix a wiring problem and you just core traded a good Denso.
 
Help... AC Compressor Failed and Alternator Stopped Charging

I strongly suggest you have the alternator tested off the truck before you replace or even service it, and that you carefully inspect your alt. wiring for damage. I am concerned you have not mentioned ever getting an alt. warning light, which I would have expected with a simple brush failure.



It could be that the bad battery coupled with a failing alt. caused this, but I still think it is important to verify that wiring. At the plug, you should get battery voltage on the white and red-blue wires (ignition on, engine off) and the alt dash light should come on if you ground the yellow-green. Also verify battery voltage at the big wire, and that its connection is solid.



Wiring issues are cheap fixes, and you feel really stupid when your new alt. does not fix a wiring problem and you just core traded a good Denso.



I remember seeing the battery light when you first stick the key in the ignition, so I know the bulb works. Other than that, I’ve never seen it come on. Not even while diving it below 10v the other night.

How would I go about testing the alternator off the truck? Or were you referring to testing the wiring?

Something could have happened to the wiring I suppose. Since it was a complete failure and not gradual, but it would have to be the alt to batt positive, right?

If I have to remove the alternator I’m going to do the ‘big 3’ while I’m at it.

Speaking of the brushes. While I’m sure mine are pretty worn down, if not nubs, what about the rest of the internals? Wouldn’t the rotor and whatever else is in there be pretty worn too?

Could a fuse have blown? The alternator fuse I remember had a clear top and looked fine.
I think the key might be to figure out what fuse or relay the dash instrumentation/odometer is connected to and that should identify the cause.


There was a distinct smell from the engine bay, but it was a new to me smell. Lol not electrical, not oil, not burnt rubber...

Don’t worry, no puppies will be harmed lol

I just need to order stuff so the wife can pick it all up so I can get to work fixing it as soon as I get home Sunday and Monday

Going to call my local Toyota and see what they want for an alternator and brushes just in case.
Alternator $215+core
Brushes/holder $23
 
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I remember seeing the battery light when you first stick the key in the ignition, so I know the bulb works. Other than that, I’ve never seen it come on. Not even while diving it below 10v the other night.

How would I go about testing the alternator off the truck? Or were you referring to testing the wiring?

A good auto/electric shop should have the equipement to do this.

Something could have happened to the wiring I suppose. Since it was a complete failure and not gradual, but it would have to be the alt to batt positive, right?

No, the little wires can cause this too. Check everything.

If I have to remove the alternator I’m going to do the ‘big 3’ while I’m at it.

Speaking of the brushes. While I’m sure mine are pretty worn down, if not nubs, what about the rest of the internals? Wouldn’t the rotor and whatever else is in there be pretty worn too?

As I said, those Densos can last forever if not abused.

Could a fuse have blown? The alternator fuse I remember had a clear top and looked fine.
I think the key might be to figure out what fuse or relay the dash instrumentation/odometer is connected to and that should identify the cause.

That's probably not a fuse, just the relay is not engaging due to low voltage.


There was a distinct smell from the engine bay, but it was a new to me smell. Lol not electrical, not oil, not burnt rubber...

Don’t worry, no puppies will be harmed lol

I just need to order stuff so the wife can pick it all up so I can get to work fixing it as soon as I get home Sunday and Monday

Going to call my local Toyota and see what they want for an alternator and brushes just in case.
Alternator $215+core
Brushes/holder $23

My answers in BOLD


Have you charged and load tested the battery, at least? A bad alt. can kill a battery fast. You NEED to start with a good charged battery or you will never figure out anything. You can throw $$ and parts at it but it is like blindfold darts. Maybe you get lucky, maybe you don't.
 
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My answers in BOLD


Have you charged and load tested the battery, at least? A bad alt. can kill a battery fast. You NEED to start with a good charged battery or you will never figure out anything. You can throw $$ and parts at it but it is like blindfold darts. Maybe you get lucky, maybe you don't.



I’m pretty limited to what I can do until I get home hopefully Saturday night.

A new battery will be going in first thing regardless since mine is at least 6 years old and is due for replacement anyways.

Once I get it in I’ll start it up and see if there’s any change. If not I’ll check the wiring and test it all like you explained. If it all looks normal I’ll bring the alternator somewhere to be tested.

If the alternator fails the test, do I just put a new brush/holder in there and have them retest it? If that fails then I’m buying a new alternator, right?

This seems like the most logical sequence
 
that first pic of the cluster is exactly what it looks like with the 10 amp "GAUGE" fuse is blown/missing. Fuse panel by your left knee. middle row second one down.

i can also confirm the AC does not function when i pull this fuse. it may kill the entire climate control system, i'm not sure. but the AC light will not come on like it normally does.

i can't comment on any affects on the alternator.

hope this helps.
 
that first pic of the cluster is exactly what it looks like with the 10 amp "GAUGE" fuse is blown/missing. Fuse panel by your left knee. middle row second one down.



i can also confirm the AC does not function when i pull this fuse. it may kill the entire climate control system, i'm not sure. but the AC light will not come on like it normally does.



i can't comment on any affects on the alternator.



hope this helps.



Thanks! Great info.

I don’t remember if I checked that fuse or not. I think I did, but not really sure. I guess I’ll toss a new one in first thing and see if it gets me anywhere. [emoji1694]

I wonder if that fuse will cut power to the alternator? Or trick the computer into thinking the engine isn’t running with no engine signal and cut the power from the alt?
 
Yes. Power from the gauge fuse turns on the alternator regulator.



-Charlie



[emoji1598] thanks!

If this is the case. Anyone know why it would’ve randomly blown? Or could something else cause it to go? Could be an old fuse.


It must be the fuel gauge that doesn’t operate correctly. It’s pissed because I use the mileage to fill up and have the 4gal rotopax up top if I do run out. Hahaha
 
Thank you to everyone for your input and suggestions!

Solution: 10a Gauge fuse.

All is working again. :)


Still don’t know why it blew in the first place, but hopefully it doesn’t happen again.

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14.1-2 at idle.

Haven’t driven it yet, but will post back if it blows again.
 

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