BrokenSocketBen
04-30-2026, 10:43 PM
Background:
Got the car about 2 and a half years ago and ran fine, so I never thought much about checking anything. Tested the battery health once and it was good, and inspected the underside a couple times, rear shocks are bad since I bought it, muffler fell off, both CV axle boots are torn one was when I bought it, the other broke since then.
After the first year the belt started squeeling alot, and eventually broke on my way to work, i replaced it at work and kept driving. Oil filters have been clean of metal or debris ( ive been checking them so I can see how different brands make them).
About two months ago and a bit my water pump seized up and had to replace that, put an aisin one in. Squeeling continued (I have tried belt dressing). About 2 weeks later I got all new tires from the shop I'm working at, since my summers were getting below wear bars. The next day when I went to drive home from work I had a "P/S" light on and no power steering, got it home and drove it right into the garage, popped the hood and I've been walking to work since. It's been about 7 weeks, since I had to pay off those new tired I knew I couldn't afford parts, so I didn't do much troubleshooting.
This is my first car with electric power steering, not on the belt drive. So I had to do some Google Foo to get some ideas. Over the weeks I read alot, and a weird amount saying the alternator or harmonic balancer are at fault.
So when I tried to start the car to test my alternator, not a drop of juice, no lights or clicks or anything. Pulled out the old multimeter I was no longer familiar with and tried to read the battery voltage, after some hit n miss I figured it out and was getting only 5v from the battery.
Managed to get a charger and charged the battery up but it wasn't holding charge very well (i was charging it, and letting it sit on a wooden shelf disconnected to test if its holding charge) Got it to 12.5v and started up the car, P/S light is gone, well that means the problem was low voltage, not anything to do with the power steering system itself. And despite the battery being 12.5v, I was getting 14.0v from the system, this tells me the alternator is supplying power. So perhaps the tales of the harmonic balancer are true?
So at this point I stop and think a while. If the battery is losing about 0.1v per 24 hours then I would never have noticed it dieing because I drive alot, until I had a week or two where I didn't go very far from home, only making small 5 minute trips, and trying to save gas. But it bugs me that the battery has a date sticker for 2022 on it, and those stickers are already on when the store gets them, I've worked in a lube shop and saw batteries with stickers already 3 years old on them. So that battery HAD to have been installed pretty recently to when I bought the car. And I'm still stuck on the belt whine that I can't find. Unless....
So the harmonic balancer theory, seems to stem from similar years of camry and corolla, and the rubber ring gets to the point that the inner part of the pulley, connected to the crank, can slide along that rubber, spinning faster than the outer metal part that drives the belt. This causes its own belt whine like sound, and under-drives the alternator which could cause the low voltage reading, making the p/s fail. This could also under-charge the battery even worse than the short trips already were. So low power from both battery and alternator at the same time, could have been the trigger. And this would explain the belt whine, which isn't from the water pump, or alternator, which leaves balancer and a/c compressor. And explains why changing tension and using dressing never changed it.
So I decide out of curiosity to scan the car, see if there's anything neet my scanner can do. So it said no codes, but I do a battery test and it says battery is fine. Well that's weird. And I find a separate code reading program within it, 4 of them. OEM specific, which found 3 codes, one for random misfire, one for cyl 2 misfire, and the last for cyl 3 misfire. Huh, so the plot thickens. Let's to the next scan, ABS, code for low power voltage. Huh, no shit. Next, SCS (safety and constraint system), has a 3 codes for passenger airbag and seat belt. Well damn. And I don't think the last one came up with anything.
So I knew about the setbelt thing, someone tugged too hard on it in a panic and since then I got a seat belt light and airbag light on. Figured I probably need a new seat belt buckle for that. The low voltage was kind of funny, given that's what I'm working on. But the misfires are new to me, and explains why the car feels low on power, and idles a little rough. The biggest problem is that I had no MIL/CEL illuminated. All these codes where here just hiding.
So now my mystery is rearranged. I plan to get to the harmonic balancer and try to pull it off and look at it up close, because it would be a convenient fix. (Compared to a/c compressor) and that belt whine is driving me insane. But now I also have to figure out this misfire, gonna get some spark plug sockets in a week or so to check my plugs and probably change them, before that I might try inspecting my coils and swapping them around and rescanning. Given it's 383k km and burns oil like crazy I'm assuming it needs plugs regardless.
So I'm gonna keep updating this as my journey goes, but what kind of things have you experienced related to this? Does the harmonic balancer theory sound possible? Has anyone had a bad harmonic balancer on a yaris? And what are some issues you have had that caused misfires? So i have more ideas to go off of.
All my experience comes from working on my own 99 TJ sport MT 242, or my 1990 F150 AT 302. Besides my work experience of tire shops and quick lube shops.
Got the car about 2 and a half years ago and ran fine, so I never thought much about checking anything. Tested the battery health once and it was good, and inspected the underside a couple times, rear shocks are bad since I bought it, muffler fell off, both CV axle boots are torn one was when I bought it, the other broke since then.
After the first year the belt started squeeling alot, and eventually broke on my way to work, i replaced it at work and kept driving. Oil filters have been clean of metal or debris ( ive been checking them so I can see how different brands make them).
About two months ago and a bit my water pump seized up and had to replace that, put an aisin one in. Squeeling continued (I have tried belt dressing). About 2 weeks later I got all new tires from the shop I'm working at, since my summers were getting below wear bars. The next day when I went to drive home from work I had a "P/S" light on and no power steering, got it home and drove it right into the garage, popped the hood and I've been walking to work since. It's been about 7 weeks, since I had to pay off those new tired I knew I couldn't afford parts, so I didn't do much troubleshooting.
This is my first car with electric power steering, not on the belt drive. So I had to do some Google Foo to get some ideas. Over the weeks I read alot, and a weird amount saying the alternator or harmonic balancer are at fault.
So when I tried to start the car to test my alternator, not a drop of juice, no lights or clicks or anything. Pulled out the old multimeter I was no longer familiar with and tried to read the battery voltage, after some hit n miss I figured it out and was getting only 5v from the battery.
Managed to get a charger and charged the battery up but it wasn't holding charge very well (i was charging it, and letting it sit on a wooden shelf disconnected to test if its holding charge) Got it to 12.5v and started up the car, P/S light is gone, well that means the problem was low voltage, not anything to do with the power steering system itself. And despite the battery being 12.5v, I was getting 14.0v from the system, this tells me the alternator is supplying power. So perhaps the tales of the harmonic balancer are true?
So at this point I stop and think a while. If the battery is losing about 0.1v per 24 hours then I would never have noticed it dieing because I drive alot, until I had a week or two where I didn't go very far from home, only making small 5 minute trips, and trying to save gas. But it bugs me that the battery has a date sticker for 2022 on it, and those stickers are already on when the store gets them, I've worked in a lube shop and saw batteries with stickers already 3 years old on them. So that battery HAD to have been installed pretty recently to when I bought the car. And I'm still stuck on the belt whine that I can't find. Unless....
So the harmonic balancer theory, seems to stem from similar years of camry and corolla, and the rubber ring gets to the point that the inner part of the pulley, connected to the crank, can slide along that rubber, spinning faster than the outer metal part that drives the belt. This causes its own belt whine like sound, and under-drives the alternator which could cause the low voltage reading, making the p/s fail. This could also under-charge the battery even worse than the short trips already were. So low power from both battery and alternator at the same time, could have been the trigger. And this would explain the belt whine, which isn't from the water pump, or alternator, which leaves balancer and a/c compressor. And explains why changing tension and using dressing never changed it.
So I decide out of curiosity to scan the car, see if there's anything neet my scanner can do. So it said no codes, but I do a battery test and it says battery is fine. Well that's weird. And I find a separate code reading program within it, 4 of them. OEM specific, which found 3 codes, one for random misfire, one for cyl 2 misfire, and the last for cyl 3 misfire. Huh, so the plot thickens. Let's to the next scan, ABS, code for low power voltage. Huh, no shit. Next, SCS (safety and constraint system), has a 3 codes for passenger airbag and seat belt. Well damn. And I don't think the last one came up with anything.
So I knew about the setbelt thing, someone tugged too hard on it in a panic and since then I got a seat belt light and airbag light on. Figured I probably need a new seat belt buckle for that. The low voltage was kind of funny, given that's what I'm working on. But the misfires are new to me, and explains why the car feels low on power, and idles a little rough. The biggest problem is that I had no MIL/CEL illuminated. All these codes where here just hiding.
So now my mystery is rearranged. I plan to get to the harmonic balancer and try to pull it off and look at it up close, because it would be a convenient fix. (Compared to a/c compressor) and that belt whine is driving me insane. But now I also have to figure out this misfire, gonna get some spark plug sockets in a week or so to check my plugs and probably change them, before that I might try inspecting my coils and swapping them around and rescanning. Given it's 383k km and burns oil like crazy I'm assuming it needs plugs regardless.
So I'm gonna keep updating this as my journey goes, but what kind of things have you experienced related to this? Does the harmonic balancer theory sound possible? Has anyone had a bad harmonic balancer on a yaris? And what are some issues you have had that caused misfires? So i have more ideas to go off of.
All my experience comes from working on my own 99 TJ sport MT 242, or my 1990 F150 AT 302. Besides my work experience of tire shops and quick lube shops.