NA - weird alternator OBDII issue on FJ - NA

Tantalum

Tantalum

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San_Diego_Pilot
Hey Guys, figured the brain trust here might have some ideas.. long-ish post but trying to give all the details to help with a prognosis.


I've had my FJ since 2011, bought it new and love the car. Plan to keep it forever and it's safely taken me on many adventures in the snow, desert, hot, cold, etc. Never had any issues with it and always did all the regular Toyota service. 90K miles now, just last week did new thermostat, transfer case flush, radiator flush, etc. Still feels "brand new" to me.


Unfortunately, this past weekend however it stranded me up in Independence, CA. Took it up for camping for the weekend and some hiking on the Kearsarge Pass. Car ran great the whole way up, however after the hike when I got in I noticed the AC fan felt "weak" .. I checked the volts of the battery and with the car running it was 11.9 (even with the AC off, fan off, everything off). I know it's not a battery issue since the battery is new, and with the car off it shows 12.4 (basically perfect). So when it's running the battery is not receiving a charge, but it is being used to run the ignition, car computer, etc. (Times like this I wish cars had magnetors so I could at least get home!)

It seems that when the car runs the alternator is not giving any juice. I rev'd the engine to 4K RPM and the volts grew from 11.9 to 12.4.. so the alternator did a very little something, but very little and I didn't trust the battery to keep long enough to drive back. If anyone doesn't know, the drive down Owens valley is very desolate and not a good place to get stranded.. it was 104*-106* the whole drive up - much better to fly!! But hard to get from Independence Airport to hiking without a car :(

The other peculiarity, I have an UltraGauge (also love it, had it since 2014) that plugs into the OBDII permanently. I have a very clean install on it so it looks factory, and that was totally dead.. so the OBDII is not getting any power. This worries me that it's not a simple alternator, but something seriously screwed up with the electronics

Other things of note:
-all the fuses are fine when checking the small fuse box in the dash
-all the fuses are fine when checking the main bus under the hood.. however this one smelled strongly of an electrical odor
-I used a 140 Watt AC inverter plugged into the 12 volt to inflate the air mattress. The plug says 120W max.. but I've never had an issue using this inverter. Plus it's on a fuse so I figured that the fuse would blow before anything gets hurt. It's a 120W fan for the air mattress so it should still be okay.. but maybe this fried something in the main computer?
-I used an add a circuit to create an extra always hot 12V outlet.. I plugged the inverter into that first and then the outlet died. This was odd, since none of the fuses blew (the add a circuit is fused with 10amps). However this was Friday night and the car worked fine Saturday morning (OBDII UltraGauge, battery showing 13.7 volts with car running)..

Oh.. also, the traction control light came on.. not the A-Trac, but the one that shows when your tires slip. Anyway.. any ideas?

Thanks Guys!
 
Tantalum said:
Hey Guys, figured the brain trust here might have some ideas.. long-ish post but trying to give all the details to help with a prognosis.


I've had my FJ since 2011, bought it new and love the car. Plan to keep it forever and it's safely taken me on many adventures in the snow, desert, hot, cold, etc. Never had any issues with it and always did all the regular Toyota service. 90K miles now, just last week did new thermostat, transfer case flush, radiator flush, etc. Still feels "brand new" to me.


Unfortunately, this past weekend however it stranded me up in Independence, CA. Took it up for camping for the weekend and some hiking on the Kearsarge Pass. Car ran great the whole way up, however after the hike when I got in I noticed the AC fan felt "weak" .. I checked the volts of the battery and with the car running it was 11.9 (even with the AC off, fan off, everything off). I know it's not a battery issue since the battery is new, and with the car off it shows 12.4 (basically perfect). So when it's running the battery is not receiving a charge, but it is being used to run the ignition, car computer, etc. (Times like this I wish cars had magnetors so I could at least get home!)

It seems that when the car runs the alternator is not giving any juice. I rev'd the engine to 4K RPM and the volts grew from 11.9 to 12.4.. so the alternator did a very little something, but very little and I didn't trust the battery to keep long enough to drive back. If anyone doesn't know, the drive down Owens valley is very desolate and not a good place to get stranded.. it was 104*-106* the whole drive up - much better to fly!! But hard to get from Independence Airport to hiking without a car :(

The other peculiarity, I have an UltraGauge (also love it, had it since 2014) that plugs into the OBDII permanently. I have a very clean install on it so it looks factory, and that was totally dead.. so the OBDII is not getting any power. This worries me that it's not a simple alternator, but something seriously screwed up with the electronics

Other things of note:
-all the fuses are fine when checking the small fuse box in the dash
-all the fuses are fine when checking the main bus under the hood.. however this one smelled strongly of an electrical odor
-I used a 140 Watt AC inverter plugged into the 12 volt to inflate the air mattress. The plug says 120W max.. but I've never had an issue using this inverter. Plus it's on a fuse so I figured that the fuse would blow before anything gets hurt. It's a 120W fan for the air mattress so it should still be okay.. but maybe this fried something in the main computer?
-I used an add a circuit to create an extra always hot 12V outlet.. I plugged the inverter into that first and then the outlet died. This was odd, since none of the fuses blew (the add a circuit is fused with 10amps). However this was Friday night and the car worked fine Saturday morning (OBDII UltraGauge, battery showing 13.7 volts with car running)..

Oh.. also, the traction control light came on.. not the A-Trac, but the one that shows when your tires slip. Anyway.. any ideas?

Thanks Guys!
Click to expand...

Yes, start simple, work from there. As the voltage gets lower weird things start happening to the electronics, so fix the voltage issue before fixing anything else. From the sound of what you write, I would say alternator or voltage regulator. Most likely the alternator. Should be relatively easy to diagnose, not familiar with the Toyota systems, but there should be plenty of videos on how to diagnose. Look for videos that use multimeters to diagnose. If you are not comfortable doing this type of work, then bring it in. I think you should get out of this for a couple hundred. Not bad for 90k of mileage.
 
13.7 running is good. 90K for an alternator is not bad IMHO. Running AC and other high demand electronics will shorten the useful life of the alternator. I only get to run the AC 2 or 3 times each year, average temp in SE AK in the summer is high 60's low 70's...:rolleyes: You could rebuild the alternator or replace. Spend the cash and get a factory new if you replace the alternator.
 
On a side note. My 2010 GMC 1500 was having issues with the traction control light coming on. I disconnected the battery for 2+ hours so the ECM and Trans modules would reset. Has worked fine ever since
 
Thanks guys, the dead OBDII worries me. I've had dead batteries in the car before and that OBD port always worked.. makes me think something with the ECU bungled when I was using the inverter

PaulS said:
https://www.tomorrowstechnician.com/toyota-charging-system-diagnostics/

Even better description, looks like Toyota uses an alternator with the voltage regulator built in. New one costs between $185 to $585. I'd go cheaper, but that's me.
Click to expand...
Thanks! interesting, it's at a Toyota dealership now so I'm guessing they'll go with the more expensive factory parts.. I guess there are pros and cons to that. The pros being it's a genuine Toyota part, the cons being that it's less flying money!

AKBill said:
is good. 90K for an alternator is not bad IMHO.
Click to expand...
man, I always thought of the car as brand new, but I guess almost 10 years and one hundred thousand miles later I have to realize that some stuff are going to start breaking and need replacing

AKBill said:
disconnected the battery
Click to expand...
That's a good idea, I should have done that..
 
Tantalum said:
man, I always thought of the car as brand new, but I guess almost 10 years and one hundred thousand miles later I have to realize that some stuff are going to start breaking and need replacing
Click to expand...
How many hours of run time did you get in 10 years? How many hours are on the alternator in your Plane..?:rolleyes:
 
AKBill said:
How many hours of run time did you get in 10 years? How many hours are on the alternator in your Plane..?:rolleyes:
Click to expand...
Haha, well, at an average of 44.4 mph (per the ultragauge referenced above) that's over 2,200 hours.. damn. I'm past TBO!
 
Tantalum said:
Haha, well, at an average of 44.4 mph (per the ultragauge referenced above) that's over 2,200 hours.. damn. I'm past TBO!
Click to expand...

Na, most of that time is probably at less than 25% power. Just broken in.
 
I'm paranoid it's the ECU or some goofy electrical issue I caused by plugging the 140 watt inverter into the 12V plug I added coming off the bus in the cabin.. the smell coming from the main bus under the hood was not encouraging either!

Techs are working on it now. We'll see!

Thanks for the help
 
FJ’s will wear out the alternator brushes. Easy fix, take it off and take to an auto electric shop, have them fix it and reinstall.

FJ owner (2008) as well. My alternator went out at 80k. Just needed brushes.
 
In the automotive world, anything remotely modern... by which I mean from the past 30+ years will probably have a voltage regulator built into the alternator. Check voltage at battery with the engine off, start the car and check it again. If it doesn’t come up, preferably to around 13-14v the alternator is probably bad.

If It fails that test and a reman from your closest auto parts store isn’t too pricy I’d just get one and swap it in. That’s what most mechanics are going to do anyway.
 
It's likely just the alternator. I seriously doubt you fried anything with the inverter, the least of which would be your ECU. A couple of hours of shop labor and a new alternator should put you back in the road. The electrical smell was likely just the burned out brushes in the alternator.
 
Tantalum said:
I'm paranoid it's the ECU or some goofy electrical issue I caused by plugging the 140 watt inverter into the 12V plug I added coming off the bus in the cabin.. the smell coming from the main bus under the hood was not encouraging either!

Techs are working on it now. We'll see!

Thanks for the help
Click to expand...
Ya left us hanging here...
 
I had an alternator go bad in a Pathfinder. Most of the same symptoms. When voltage gets low, computer systems do weird things with everything in car - when my alternator went, every trouble light came on like a christmas tree.
 
PaulS said:
Yes, start simple, work from there. As the voltage gets lower weird things start happening to the electronics
Click to expand...

Tantalum said:
Thanks guys, the dead OBDII worries me. I've had dead batteries in the car before and that OBD port always worked.. makes me think something with the ECU bungled when I was using the inverter
Click to expand...

wsuffa said:
I had an alternator go bad in a Pathfinder. Most of the same symptoms. When voltage gets low, computer systems do weird things with everything in car - when my alternator went, every trouble light came on like a christmas tree.
Click to expand...

Yup, new computer controlled cars do STRANGE things when the computers and sensors are undervolt. I had a Grand Cherokee that would turn the air conditioning on and off all by itself, then the power windows started going up and down by themselves. I thought the car was FUBAR, took it to the dealer expecting a big bill. Nope, just needed a new battery, all the symptoms went away.

Lesson learned. Car starts doing really strange electronic things, start with the battery/alternator first.
 
PaulS said:
Ya left us hanging here...
Click to expand...
haha, I am awaiting results from Toyota with bated breath

Thanks for all the tips guys and the feedback.. here's what I know so far

-the alternator is definitely toast.. that was ordered new from Toyota and will arrive today and get installed today.. from there we'll see if the other issues restore themselves. The burning smell was likely from the alternator

I did some digging and learned that the car only thinks of itself as "on" when there is an initial battery voltage spike that exceeds 13.2 volts with the ignition in the "run" position, indicating a charging battery and full operational car. Since the alternator is dead that voltage jump will not occur, and certain things will stay in limbo since it doesn't think of the car as on.. sort of to @Bill Jennings point. My OBDII port is not dead, however the aftermarket additional gauge cluster I have reading off of it (neat factory looking install in the overhead above the rearview) doesn't turn itself on also in the absence of that voltage jump. Neat!

I'm hoping it's just the alternator they quoted me, new from Toyota is just $300 plus $200 labor.. I feel like I'm getting off easy if this turns out to only cost me $500 so I was holding off reporting back

But that's where we stand!
 
In other places outside of the PRC that alternator (OEM) is about $230 exchange. The labor doesn't seem to far off, it's easier to take it out from the bottom than the top.
 
My 2020 RAM lit up like a Christmas Tree one day (I swear it was related to driving through a puddle). Check Engine light, Anticollision system failure, Adaptive Cruise Control failure, Trailer Brakes failure, and probably a few others. Turns out it was a known failure but the solution was not reassuring: reset the codes.
 
flyingron said:
Turns out it was a known failure but the solution was not reassuring: reset the codes
Click to expand...
Would make me wonder what caused them to go off in the first place! That's akin to resetting a constantly popping CB in the cockpit..
 
Tantalum said:
haha, I am awaiting results from Toyota with bated breath

Thanks for all the tips guys and the feedback.. here's what I know so far

-the alternator is definitely toast.. that was ordered new from Toyota and will arrive today and get installed today.. from there we'll see if the other issues restore themselves. The burning smell was likely from the alternator

I did some digging and learned that the car only thinks of itself as "on" when there is an initial battery voltage spike that exceeds 13.2 volts with the ignition in the "run" position, indicating a charging battery and full operational car. Since the alternator is dead that voltage jump will not occur, and certain things will stay in limbo since it doesn't think of the car as on.. sort of to @Bill Jennings point. My OBDII port is not dead, however the aftermarket additional gauge cluster I have reading off of it (neat factory looking install in the overhead above the rearview) doesn't turn itself on also in the absence of that voltage jump. Neat!

I'm hoping it's just the alternator they quoted me, new from Toyota is just $300 plus $200 labor.. I feel like I'm getting off easy if this turns out to only cost me $500 so I was holding off reporting back

But that's where we stand!
Click to expand...

Surprised they didn't have the alternator in stock. Sounds like you will be all set and the charges seem inline to me. Hope it fixes it, but I'm pretty sure it will.
 
PaulS said:
Surprised they didn't have the alternator in stock. Sounds like you will be all set and the charges seem inline to me. Hope it fixes it, but I'm pretty sure it will.
Click to expand...
Thanks! The car is in the middle of nowhere, the dealership there probably has limited inventory in stock.. and the FJ's been out of production :( since 2014.. at least in the US and most major markets. Although I believe you can still get one in the Middle East?
 
Tantalum said:
Would make me wonder what caused them to go off in the first place! That's akin to resetting a constantly popping CB in the cockpit..
Click to expand...

Yeah, the code was something like "Improbable RPM readout from transfer case" or something along those lines. Why it killed a disparate range of services, I do not know. Also, why it didn't reset if it just happened once. I've been driving it through puddles a lot trying to recreate it before the warranty runs out.
 
Tantalum said:
Thanks! The car is in the middle of nowhere, the dealership there probably has limited inventory in stock.. and the FJ's been out of production :( since 2014.. at least in the US and most major markets. Although I believe you can still get one in the Middle East?
Click to expand...
Good luck!

Bet Napa has the part...
 
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