Low voltage while in Drive
Thread Starter
Racer
Joined: Oct 2016
Posts: 424
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From: Charlotte, NC
Low voltage while in Drive
I have just recently purchased my 2006 Acura TL 5AT with 100k miles. It's already had some issues within my first month of ownership. I'm not too happy because I just came from a car that was a total lemon and this one is shaping up to be the same.Currently, I am having an issue with the voltage in the car dropping to 12V while in Drive. While I am driving around, I am noticing the voltage anywhere from 12.2-12.6. If I give it quite a bit of gas, it will shoot back up to 13.8, but will almost immediately come back down. If I am stopped at a light too long while having this issue, it seems like the car wants to cut itself off. I have installed an aftermarket HU that displays voltage and have two amps running currently. Nothing that should be straining the electrical system too much. Only about 550W right now. The car maintains a steady 13.8 volts in Park with the system at max-ish volume no problems. I don't believe this is an issue that I have caused.The weirdest thing about the whole situation is the low voltage ONLY occurs while in Drive. If I shift into Neutral or Park, voltage goes immediately back up to a steady 13.8 to 14.0V. The issue with the low voltage also seems to be intermittent. On my way into work today, I had no issues with the voltage at all. Yesterday while driving around, the issue would not go away.Battery is basically brand new, my old one died 10 days after owning the car... I had the alternator checked at AutoZone and it read out fine, but it was in Park and the issue only occurs while in Drive and only after I have started to drive around. Especially if the car is warm.Another issue I noticed is that if I rev the car in Park on a cold start, I hear this like screeching/almost grinding noise at about 2k to 3k RPMs. Possible belt slipping? Timing belt was done right before I got the car from an Acura dealership.My only other thoughts are a possible failure in the voltage regulator?
Any thoughts?
I can try and provide any more information if need be! Thanks!
Any thoughts?
I can try and provide any more information if need be! Thanks!
Check to make certain that the serpentine belt is tight and the tensioner is within range. There's marks on the
tensioner reflecting the correct position. Sorry, on vacation and not much time to give further info.
With volt meter, check at bat terminals, then cable ends, then at back of alternator to make certain all reflect the same value.
You can always check amps, but I'd say alt kaput.
tensioner reflecting the correct position. Sorry, on vacation and not much time to give further info.
With volt meter, check at bat terminals, then cable ends, then at back of alternator to make certain all reflect the same value.
You can always check amps, but I'd say alt kaput.
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I never trust the alternator tests at the 'Zone.. i've had instances where parts check out fine but still end up being the culprit. Second turbo's suggestion though.. it can be a loose tension issue with the belt causing the alternator to not spin consistently.
Timing belt =/= serpentine belt. Check the condition and replace that and the tensioner.
Upon further reading the screeching plus poor voltage definitely sounds a lot like a belt issue.
Timing belt =/= serpentine belt. Check the condition and replace that and the tensioner.
Upon further reading the screeching plus poor voltage definitely sounds a lot like a belt issue.
Thread Starter
Racer
Joined: Oct 2016
Posts: 424
Likes: 60
From: Charlotte, NC
Yeah, that's kinda what I'm thinking. It's intermittent. Today I had no issues on my way to work. I will try and get a look at the tensioner today after work. The belt looks like it is in good shape, just based on inspection, but I will inspect it more thoroughly tonight as well.
If it was the alternator dying, I would assume that no matter what gear the car was in, it would be having voltage issues, not just in drive. Right?
What are the odds the voltage regulator is going bad?
Thanks for the replies.
If it was the alternator dying, I would assume that no matter what gear the car was in, it would be having voltage issues, not just in drive. Right?
What are the odds the voltage regulator is going bad?
Thanks for the replies.
Just remember, the faster the rpm's, the faster the alternator spins and if no problem at full power, it
can be seen at a low idle engine speed. Not necessarily on the TL, but on certain applications, some try
to overcome the problem and change to a smaller pulley.
Certainly you've seen cars that have had a lot of equipment running at idle, lights, amps, a/c, etc and when the engine
speeds up, the accessories will also increase in performance.
Not much for replies from other forums, buy:
https://www.ericthecarguy.com/kunena...charge-at-idle
can be seen at a low idle engine speed. Not necessarily on the TL, but on certain applications, some try
to overcome the problem and change to a smaller pulley.
Certainly you've seen cars that have had a lot of equipment running at idle, lights, amps, a/c, etc and when the engine
speeds up, the accessories will also increase in performance.
Not much for replies from other forums, buy:
https://www.ericthecarguy.com/kunena...charge-at-idle
Thread Starter
Racer
Joined: Oct 2016
Posts: 424
Likes: 60
From: Charlotte, NC
I think I've solved the "issue."
It's not actually an issue, although I do wish there were an easy way to bypass this.
Basically all Honda's made since the mid-90's use an Electrical Load Detector (ELD) that sends a signal to the PCM to turn the alternator on or off depending on the charge detected on the battery. So when the PCM senses the battery is charged to full, it will stop running the alternator and voltage on the battery will drop to 12.0-12.6 during normal driving conditions. This measure was put into place by Honda to help with fuel economy.
With the volt meter on my HU, I was initially concerned with the voltage drops because I never saw anywhere below 13.4 on my old car even with my sound system running full power. Since the head unit is based on ignition power and feeds into the ELD and the aftermarket system is drawing right from the positive terminal on the battery, the ELD does not detect the extra load from the sound system on the battery and continues to function as normal. There are ways to bypass this, but when I looked at it, it required splicing factory wires and I do not want to start doing that. The most I was willing to do was cut the metal in my door panels to fit my aftermarket 6.5" woofers and run the wires through the factory door loom.
Hopefully this information will help someone down the line. My alternator seems to be good, when it IS running, I get a solid 13.8-14.1V. My battery is essentially a brand new AGM battery.
There is still something wrong with one of my components on the serpentine belt, but I do not think it is directly related to the voltage issue after the research that I have done. I will probably replace the tensioner, idler pulley, and belt soon as the car is at 101k miles. There is play in one of the serpentine belt components, I believe it's the tensioner, and a sound that almost sounds like a bad bearing, hard to describe in words. Looks like the Gates parts are about $80-$90 on RockAuto, not bad.
It's not actually an issue, although I do wish there were an easy way to bypass this.
Basically all Honda's made since the mid-90's use an Electrical Load Detector (ELD) that sends a signal to the PCM to turn the alternator on or off depending on the charge detected on the battery. So when the PCM senses the battery is charged to full, it will stop running the alternator and voltage on the battery will drop to 12.0-12.6 during normal driving conditions. This measure was put into place by Honda to help with fuel economy.
With the volt meter on my HU, I was initially concerned with the voltage drops because I never saw anywhere below 13.4 on my old car even with my sound system running full power. Since the head unit is based on ignition power and feeds into the ELD and the aftermarket system is drawing right from the positive terminal on the battery, the ELD does not detect the extra load from the sound system on the battery and continues to function as normal. There are ways to bypass this, but when I looked at it, it required splicing factory wires and I do not want to start doing that. The most I was willing to do was cut the metal in my door panels to fit my aftermarket 6.5" woofers and run the wires through the factory door loom.
Hopefully this information will help someone down the line. My alternator seems to be good, when it IS running, I get a solid 13.8-14.1V. My battery is essentially a brand new AGM battery.
There is still something wrong with one of my components on the serpentine belt, but I do not think it is directly related to the voltage issue after the research that I have done. I will probably replace the tensioner, idler pulley, and belt soon as the car is at 101k miles. There is play in one of the serpentine belt components, I believe it's the tensioner, and a sound that almost sounds like a bad bearing, hard to describe in words. Looks like the Gates parts are about $80-$90 on RockAuto, not bad.
I think I've solved the "issue."
It's not actually an issue, although I do wish there were an easy way to bypass this.
Basically all Honda's made since the mid-90's use an Electrical Load Detector (ELD) that sends a signal to the PCM to turn the alternator on or off depending on the charge detected on the battery. So when the PCM senses the battery is charged to full, it will stop running the alternator and voltage on the battery will drop to 12.0-12.6 during normal driving conditions. This measure was put into place by Honda to help with fuel economy.
It's not actually an issue, although I do wish there were an easy way to bypass this.
Basically all Honda's made since the mid-90's use an Electrical Load Detector (ELD) that sends a signal to the PCM to turn the alternator on or off depending on the charge detected on the battery. So when the PCM senses the battery is charged to full, it will stop running the alternator and voltage on the battery will drop to 12.0-12.6 during normal driving conditions. This measure was put into place by Honda to help with fuel economy.
The only cars I know of that adjust alt output are some new models that allow a charge while coasting,
but not under hard acceleration. Similar to some cars with A/C in that the compressor cuts outs under
heavy acceleration.
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Thread Starter
Racer
Joined: Oct 2016
Posts: 424
Likes: 60
From: Charlotte, NC
I found most of the information here: Meet your ELD - Electrical Load Detector.... - Honda Civic Forum
The voltage is only cutting down to 12.0 volts when I am at a dead stop. When it is displaying 12.6-ish volts, I am driving at speeds <40mph. On the highway, it seems to maintain 13.8V or higher.
The voltage is only cutting down to 12.0 volts when I am at a dead stop. When it is displaying 12.6-ish volts, I am driving at speeds <40mph. On the highway, it seems to maintain 13.8V or higher.
Thread Starter
Racer
Joined: Oct 2016
Posts: 424
Likes: 60
From: Charlotte, NC
Yeah, I mentioned that. Something is definitely wrong with the drive belt. Honestly, it doesn't look like there is a tensioner on it. It looks like two idler pulleys.
At least the Gates tensioner I am looking at on RockAuto looks nothing like what is in its place in the car.
There's a rattling like noise that is coming from one of the drive belt components. Hard to pinpoint exactly which one, but definitely some component on the drive belt is bad. Where the tensioner should be located, that piece is shaking around a little bit.
At least the Gates tensioner I am looking at on RockAuto looks nothing like what is in its place in the car.
There's a rattling like noise that is coming from one of the drive belt components. Hard to pinpoint exactly which one, but definitely some component on the drive belt is bad. Where the tensioner should be located, that piece is shaking around a little bit.
^ Got to say you are correct in that the Acura has the ELD in the box. Thought only the "old" Hondas had
the ELD, so had to do some research.
Looks like the LCD will hold voltage at 12.4/12.9, and only if all the following conditions are met:
Electrical load below 15 amps
Vehicle speed between 10-45 mph or in drive at idle
Engine speed below 3,000 rpm
Coolant temp >167 degrees F (75C)
A/C switch off
Intake air temp above 68 degrees F (20C)
the ELD, so had to do some research.
Looks like the LCD will hold voltage at 12.4/12.9, and only if all the following conditions are met:
Electrical load below 15 amps
Vehicle speed between 10-45 mph or in drive at idle
Engine speed below 3,000 rpm
Coolant temp >167 degrees F (75C)
A/C switch off
Intake air temp above 68 degrees F (20C)
^ Got to say you are correct in that the Acura has the ELD in the box. Thought only the "old" Hondas had
the ELD, so had to do some research.
Looks like the LCD will hold voltage at 12.4/12.9, and only if all the following conditions are met:
Electrical load below 15 amps
Vehicle speed between 10-45 mph or in drive at idle
Engine speed below 3,000 rpm
Coolant temp >167 degrees F (75C)
A/C switch off
Intake air temp above 68 degrees F (20C)
the ELD, so had to do some research.
Looks like the LCD will hold voltage at 12.4/12.9, and only if all the following conditions are met:
Electrical load below 15 amps
Vehicle speed between 10-45 mph or in drive at idle
Engine speed below 3,000 rpm
Coolant temp >167 degrees F (75C)
A/C switch off
Intake air temp above 68 degrees F (20C)
Thread Starter
Racer
Joined: Oct 2016
Posts: 424
Likes: 60
From: Charlotte, NC
^ Got to say you are correct in that the Acura has the ELD in the box. Thought only the "old" Hondas had
the ELD, so had to do some research.
Looks like the LCD will hold voltage at 12.4/12.9, and only if all the following conditions are met:
Electrical load below 15 amps
Vehicle speed between 10-45 mph or in drive at idle
Engine speed below 3,000 rpm
Coolant temp >167 degrees F (75C)
A/C switch off
Intake air temp above 68 degrees F (20C)
the ELD, so had to do some research.
Looks like the LCD will hold voltage at 12.4/12.9, and only if all the following conditions are met:
Electrical load below 15 amps
Vehicle speed between 10-45 mph or in drive at idle
Engine speed below 3,000 rpm
Coolant temp >167 degrees F (75C)
A/C switch off
Intake air temp above 68 degrees F (20C)
I would have to confirm that this seems accurate. Whenever my voltage is dropping, I definitely haven't had my headlights or AC on.
I also had only noticed it when I was stop and go around lights in town. I can't say exact MPH I was going, but if voltage was low, I was certainly doing lower speeds.
Cannot confirm the RPM's, but if I gave it harder acceleration, voltage would shoot back up and then drop again, so the 3k RPM definitely sounds right.
Temperatures I obviously can't confirm, but whenever this issue starts, it is after the car has been warmed up for awhile.
Thanks again, super helpful!
4th Gear
Joined: Dec 2019
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I think I've solved the "issue."
It's not actually an issue, although I do wish there were an easy way to bypass this.
Basically all Honda's made since the mid-90's use an Electrical Load Detector (ELD) that sends a signal to the PCM to turn the alternator on or off depending on the charge detected on the battery. So when the PCM senses the battery is charged to full, it will stop running the alternator and voltage on the battery will drop to 12.0-12.6 during normal driving conditions. This measure was put into place by Honda to help with fuel economy.
With the volt meter on my HU, I was initially concerned with the voltage drops because I never saw anywhere below 13.4 on my old car even with my sound system running full power. Since the head unit is based on ignition power and feeds into the ELD and the aftermarket system is drawing right from the positive terminal on the battery, the ELD does not detect the extra load from the sound system on the battery and continues to function as normal. There are ways to bypass this, but when I looked at it, it required splicing factory wires and I do not want to start doing that. The most I was willing to do was cut the metal in my door panels to fit my aftermarket 6.5" woofers and run the wires through the factory door loom.
Hopefully this information will help someone down the line. My alternator seems to be good, when it IS running, I get a solid 13.8-14.1V. My battery is essentially a brand new AGM battery.
There is still something wrong with one of my components on the serpentine belt, but I do not think it is directly related to the voltage issue after the research that I have done. I will probably replace the tensioner, idler pulley, and belt soon as the car is at 101k miles. There is play in one of the serpentine belt components, I believe it's the tensioner, and a sound that almost sounds like a bad bearing, hard to describe in words. Looks like the Gates parts are about $80-$90 on RockAuto, not bad.
It's not actually an issue, although I do wish there were an easy way to bypass this.
Basically all Honda's made since the mid-90's use an Electrical Load Detector (ELD) that sends a signal to the PCM to turn the alternator on or off depending on the charge detected on the battery. So when the PCM senses the battery is charged to full, it will stop running the alternator and voltage on the battery will drop to 12.0-12.6 during normal driving conditions. This measure was put into place by Honda to help with fuel economy.
With the volt meter on my HU, I was initially concerned with the voltage drops because I never saw anywhere below 13.4 on my old car even with my sound system running full power. Since the head unit is based on ignition power and feeds into the ELD and the aftermarket system is drawing right from the positive terminal on the battery, the ELD does not detect the extra load from the sound system on the battery and continues to function as normal. There are ways to bypass this, but when I looked at it, it required splicing factory wires and I do not want to start doing that. The most I was willing to do was cut the metal in my door panels to fit my aftermarket 6.5" woofers and run the wires through the factory door loom.
Hopefully this information will help someone down the line. My alternator seems to be good, when it IS running, I get a solid 13.8-14.1V. My battery is essentially a brand new AGM battery.
There is still something wrong with one of my components on the serpentine belt, but I do not think it is directly related to the voltage issue after the research that I have done. I will probably replace the tensioner, idler pulley, and belt soon as the car is at 101k miles. There is play in one of the serpentine belt components, I believe it's the tensioner, and a sound that almost sounds like a bad bearing, hard to describe in words. Looks like the Gates parts are about $80-$90 on RockAuto, not bad.
You saved me a LOT of hassle figuring this all out and then posting about it. And I learned something new!
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