Just noticed this last night
11-06-08, 08:34 AM
#1
Just noticed this last night
Something weird seems to be happening to my 98 ES300.
Last night I noticed that with the engine running when I opened my door the dome light was flickering(pulsating). It is just slightly so barely noticeable.
I wonder if this is a common problem or if this is a battery/connection issue.
Anyone else have this problem?
Is there a fix for it?
Last night I noticed that with the engine running when I opened my door the dome light was flickering(pulsating). It is just slightly so barely noticeable.
I wonder if this is a common problem or if this is a battery/connection issue.
Anyone else have this problem?
Is there a fix for it?
11-06-08, 09:24 AM
#4
Lexus Test Driver
Replacing the alternator is a simple job. This just seems like the issue, But then again, it could be something else. Best bet would be to go to a part store and have them run a free electrical check out on your car.
11-06-08, 10:01 PM
#7
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11-06-08, 10:41 PM
#9
Lead Lap
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If you have a shorted, or open diode, you will see a significant increase in the amount of ripple out of the alternator (all alternators have ripple). With a volt meter, you will be able to measure this ripple, (normally you would use a O'scope, but most people do not have access to this tool). By putting the voltmeter on AC volts (alternating Volts) you will be able to measure the amount of ripple. The alternator generates 3 phase ac current, this current is rectified by a three phase diode pack inside the alternator. The battery acts as a large capacitor (ie removes the ripple from the alternator). The bottom line is that if there is a open, or shorted diode, you can easily measure this with a voltmeter. Trust me on this one, 1 of my ase certs, is auto electical systems.
Ps. I would first try idling your car at night, step out of the car, close the door, and then open the passenger door. Next close all the doors and turn on the overhead light, does it still flicker? This problem could be as simple at the driver door switch starting to go bad. It is always a good idea to check the basics before going into details. Also, if the battery terminals are corroded/dirty, by all means clean them. I know how much they charge at the shop I use to work at, it is well worth your time to take care of the basics before paying someone to look at it. I am amazed at the number of people who will send their car to a dealer for a poorly running car, before they will spend the money to do a tuneup.
Ps. I would first try idling your car at night, step out of the car, close the door, and then open the passenger door. Next close all the doors and turn on the overhead light, does it still flicker? This problem could be as simple at the driver door switch starting to go bad. It is always a good idea to check the basics before going into details. Also, if the battery terminals are corroded/dirty, by all means clean them. I know how much they charge at the shop I use to work at, it is well worth your time to take care of the basics before paying someone to look at it. I am amazed at the number of people who will send their car to a dealer for a poorly running car, before they will spend the money to do a tuneup.
Last edited by GEORGE_JET; 11-07-08 at 12:16 AM.
11-07-08, 07:16 AM
#10
If you have a shorted, or open diode, you will see a significant increase in the amount of ripple out of the alternator (all alternators have ripple). With a volt meter, you will be able to measure this ripple, (normally you would use a O'scope, but most people do not have access to this tool). By putting the voltmeter on AC volts (alternating Volts) you will be able to measure the amount of ripple. The alternator generates 3 phase ac current, this current is rectified by a three phase diode pack inside the alternator. The battery acts as a large capacitor (ie removes the ripple from the alternator). The bottom line is that if there is a open, or shorted diode, you can easily measure this with a voltmeter. Trust me on this one, 1 of my ase certs, is auto electical systems.
Ps. I would first try idling your car at night, step out of the car, close the door, and then open the passenger door. Next close all the doors and turn on the overhead light, does it still flicker? This problem could be as simple at the driver door switch starting to go bad. It is always a good idea to check the basics before going into details. Also, if the battery terminals are corroded/dirty, by all means clean them. I know how much they charge at the shop I use to work at, it is well worth your time to take care of the basics before paying someone to look at it. I am amazed at the number of people who will send their car to a dealer for a poorly running car, before they will spend the money to do a tuneup.
Ps. I would first try idling your car at night, step out of the car, close the door, and then open the passenger door. Next close all the doors and turn on the overhead light, does it still flicker? This problem could be as simple at the driver door switch starting to go bad. It is always a good idea to check the basics before going into details. Also, if the battery terminals are corroded/dirty, by all means clean them. I know how much they charge at the shop I use to work at, it is well worth your time to take care of the basics before paying someone to look at it. I am amazed at the number of people who will send their car to a dealer for a poorly running car, before they will spend the money to do a tuneup.
11-07-08, 04:27 PM
#11
Lead Lap
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Yes, you are correct in the fact that the alternator is putting out dc. But internally, the alternator is producing 3 phase ac power. There is a full wave 3 phase diode pack that converts the ac power into dc power. If you are familar with ac current, then just think of each phase being 120 deg lagging the previous phase. The diode pack inverts the neg going current, and turns them into positive.
Now if you can picture the output of this diode pack being a series of sine waves (only the positive peaks) that now lag the previous by 60 deg (due to the diode pack inverting the neg peaks). You now know what is actually comming out of the alternator. The battery is what smooths out the peaks, and keeps the electronics from seeing these peaks and flipping out. Most people are familiar with alternator whine on a car stereo, this is what is one of the things that generate it, and why they add capacitors to help smooth it out.
So if you follow me up to that point, ( I realize that I am not the best at explaning things). You may then understand the concept of using AC volts to check the output of the alternator. You already understand how you use DC volts to check that the alternator is putting out the proper voltage. By using AC volts, you can see how much the voltage drops between the sine wave peaks coming out of the alternator. If you have a open, or shorted diode, those 120 peaks per revolution will be disturbed, and the voltage will drop a little further (as in a open diode) or significantly (as a shorted diode).
Basically you should be seeing significantly below .5 volts, off the top of my head I don't remember the exact amount. It has been a little while since I've had issue with the alternators ripple. I normally go over to one of the other cars in the shop and get a referance to go off
Now if you can picture the output of this diode pack being a series of sine waves (only the positive peaks) that now lag the previous by 60 deg (due to the diode pack inverting the neg peaks). You now know what is actually comming out of the alternator. The battery is what smooths out the peaks, and keeps the electronics from seeing these peaks and flipping out. Most people are familiar with alternator whine on a car stereo, this is what is one of the things that generate it, and why they add capacitors to help smooth it out.
So if you follow me up to that point, ( I realize that I am not the best at explaning things). You may then understand the concept of using AC volts to check the output of the alternator. You already understand how you use DC volts to check that the alternator is putting out the proper voltage. By using AC volts, you can see how much the voltage drops between the sine wave peaks coming out of the alternator. If you have a open, or shorted diode, those 120 peaks per revolution will be disturbed, and the voltage will drop a little further (as in a open diode) or significantly (as a shorted diode).
Basically you should be seeing significantly below .5 volts, off the top of my head I don't remember the exact amount. It has been a little while since I've had issue with the alternators ripple. I normally go over to one of the other cars in the shop and get a referance to go off
Last edited by GEORGE_JET; 11-07-08 at 11:50 PM.
11-11-08, 09:03 PM
#12
UPDATE:
I took the car to the local AutoZone to have them test the alternator.
Turns out it's good but the battery was bad so I had it replaced.
However, the problem still exists.
Not sure what to do next.
I took the car to the local AutoZone to have them test the alternator.
Turns out it's good but the battery was bad so I had it replaced.
However, the problem still exists.
Not sure what to do next.
11-16-08, 04:10 PM
#13
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Was your radio on, possibly playing bass heavy music? Were you running any other electrical accessories or have a sub in the trunk? Heavy electrical usage puts a greater load on the alternator, especially at idle, and can flicker the dome lights (or even headlights for that matter). I know when I'm idling with my sub going I can visibly see pulses in the lights when they are on. You'll also notice that if you have your dome light on and turn the A/C, heater, seat heaters, etc that the light will probably dim.
Nonetheless it's not something to worry about.
Sounds like you got jobbed with the "bad battery" diagnosis, unless you were having trouble starting.
Anyway my suggestion would be ignore the pulsating light. Alternatively don't open the door with the engine running.
Nonetheless it's not something to worry about.
Anyway my suggestion would be ignore the pulsating light. Alternatively don't open the door with the engine running.
11-16-08, 05:56 PM
#14
Was your radio on, possibly playing bass heavy music? Were you running any other electrical accessories or have a sub in the trunk? Heavy electrical usage puts a greater load on the alternator, especially at idle, and can flicker the dome lights (or even headlights for that matter). I know when I'm idling with my sub going I can visibly see pulses in the lights when they are on. You'll also notice that if you have your dome light on and turn the A/C, heater, seat heaters, etc that the light will probably dim.
Nonetheless it's not something to worry about.
Sounds like you got jobbed with the "bad battery" diagnosis, unless you were having trouble starting.
Anyway my suggestion would be ignore the pulsating light. Alternatively don't open the door with the engine running.
Nonetheless it's not something to worry about.
Sounds like you got jobbed with the "bad battery" diagnosis, unless you were having trouble starting.
Anyway my suggestion would be ignore the pulsating light. Alternatively don't open the door with the engine running.
Ha ha, yeah, I won't open the door or turn the light on with the engine running anymore.
On a serious note, I don't have any electrical modifications on the car.
It's bone stock.
I only had the car on and nothing else.
Just opened the door and noticed the dome light flickering a bit.
It's very subtle so I didn't notice it in the past.
I just happened to look at the light this time.
Just gonna drive it till who knows what happens to it.
11-18-08, 08:49 PM
#15
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G'day oceanview.
the best bet for you is to go to another auto elec and tell them the problem and get them to do another free check (and hope they dont say that yr battery is rubbish.... if they do say it - run!). Sounds to me like the rectifier is on the way out.
As an aside... put my ol Toyota Crown in to the dealer (years ago) and told them that "the charge light comes on dimly sometimes, especailly when lots of things switched on". I got the car back, they said its fixed - and all they had done was (not joking) painted the charge light bulb black..... Enjoy!
pete
the best bet for you is to go to another auto elec and tell them the problem and get them to do another free check (and hope they dont say that yr battery is rubbish.... if they do say it - run!). Sounds to me like the rectifier is on the way out.
As an aside... put my ol Toyota Crown in to the dealer (years ago) and told them that "the charge light comes on dimly sometimes, especailly when lots of things switched on". I got the car back, they said its fixed - and all they had done was (not joking) painted the charge light bulb black..... Enjoy!
pete
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