2000 Sienna Dome Light Flicker

Alright, I see another post in this group from years ago that says this is normal. Anyway, I have a 2000 Sienna and just recently replaced the battery. All appeared well, but at night, I noticed that the dome lights and Instrument panel had a slight flicker. Kind of like something was turning on and off and drawing the voltage down (however a digital voltmeter shows the variation to only be .3 volts or so worse case). This only happens when the car is running and really is only visible at night. Looking at the battery terminals they were pretty cruddy from acid so I replaced them. That seemed to make the instrument panel flicker almost disappear, but you still see it in the dome lights. Battery is being charged fine if I check the specific gravity. The only thing I notice is after starting the car, the voltage is in the 13.8 range, but after driving a short time, it works its way up to about 14.4. So far as I can see everything seems to be working as expected. Its just that I have never seen a constant flicker like this before. Kind of makes me wonder if there is a slight AC component in there.

Anyway, am I just chasing my tail and should I just let it go or is there something going on here?

Thanks, Ken

Reply to
Ken
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Did you try replacing the bulb? It may be the defective part and wouldn't cost much to eliminate.

Reply to
badgolferman

If everything with the battery is okay, then the flicker isn't anything to get excited about. It is caused by the voltage regulator hunting for it's target voltage. This will happen when the current draw is high (headlights on or battery charge low) and while the engine RPM is low. Once your engine speed gets up to normal operating range (over 1,000 rpm) the alternator output is enough that it isn't running close to it's maximum, the voltage regulator will have plenty of reserve current available and the flicker should stop. If it continues then you either have a problem with the voltage regulator or the battery.

Digital volt meters don't monitor the voltage all the time like an analog meter. They sample-and-hold and the sample interval depends on the clock rate of the meter. Cheaper ones have a slower clock and a longer interval between samples. It is entirely possible that there could be a spike in voltage that a digital meter misses altogether.

I would also add that the voltage meter on your dash is heavily dampened. They do that so that the meter isn't jumping around as the electrical load changes causing you to think that something is wrong. Then again, most analog dash gauges today are driven by the computer and are basically digital meters with an analog readout.

Reply to
Retired VIP

Did the lights flicker before you replaced the battery?

Reply to
Ray O

Notice that I said lights and the dashboard lights. Seems to be everywhere, but most noticeable on the dome lights.

Reply to
Ken

Not sure. It's something I happened to notice afterward!

Reply to
Ken

OK, if you are just getting the flicker at idle, don't worry. If it happens at higher RPM, you may have a problem.

Reply to
Ray O

I have a digital voltage monitor plugged into the accessory socket. I know that it has a certain sample rate, but thought I may see a spike on it. Anyway, this does not ever settle down. The van has the headlights on all the time, although it is at reduced voltage until you turn them on - running lights. The other thing that is odd is that the voltage drops down when I turn on lights, fans, and turn signals and then climbs back up as I would expect. But as I am driving and the voltage is sitting at 14.3 or so, it all of the sudden will drop down to 13.5 and then slowly work its way back up. I guess there could be something drawing massive current, but not sure what. I suspect that the voltage regulator is on its way out. I also thought that this vehicle had an alternator/regulator combo, but if I go to parts houses and look it up, they sell a separate voltage regulator (although I may have to open the alternator to replace it). Anyone know where the voltage regulator is in a 2000 Sienna? The important part here is that the flicker never stops. I have a Subaru and if I plug the meter into it it does not wonder around as much as the Sienna. The Subaru is pretty much fixed at 14.4 volts no matter what is going on. Whereas on the Sienna, the voltage wonders all over the place. Readings every second go like 14.4, 14.1, 14.3, 14.2, 14.4, etc.... Seems to never settle in even at highway speeds.

Reply to
Ken

A 1 volt variance is not anything to be concerned about. Your Sienna probably has a lot more equipment than the Subaru, placing a bigger load on the electrical system. For example, if you have automatic temperature control, the AC clutch will cycle on and off, the servos will draw power to adjust the dampers, and the HVAC fan will vary its speed. It is possible that your battery is not quite up to snuff or that the replacement battery clamps are not making a good contact.

Reply to
Ray O

Your vehicle has a solid-state voltage regulator and they don't usually go bad gradually. They either work or they don't so I don't think your voltage fluctuation is caused by the voltage regulator. The voltage regulator's response to voltage changes is slightly modified to keep it from overshooting it's set point by a large margin and zapping the car's electronics. It has a fast attack time for voltage spikes and a slower attack time for voltage drops. This slows down the regulator's response to voltage changes and, if you have changes in the car's current drain, the regulator will tend to lag behind.

That said, unless you have big changes in current draw, the voltage should settle down once the battery has been recharged from starting the engine. If you have an analog voltmeter, use that to monitor your battery voltage. If the changes are gradual or drifting in nature, you've got nothing to worry about. If the changes are spikes, you might want to go over your battery terminals again and make sure that you have good contact between the battery posts and terminals. If everything looks good but you still have the fluctuations then either live with them or spend hundreds of bucks searching for the problem.

Reply to
Retired VIP

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