main70072

I start noticing this problem a few weeks back but couldn't figure out what caused it. When I am driving the D4 light on the spedometer gets dim, then bright. I noticed that when I step on the gas pedal, the D4 light dims and brightens again when I lift my foot off the pedal. Even the slightest touch to the gas pedal will dim the light, and brightens when I let it go immediately. This only happens when the car has warmed up to its normal operating temperature. With my foot on the gas pedal driving at a constant speed, the D4 light only dims for about a couple of mins and brightens again and does the same every few minutes. This all happens with the a/c off. With the a/c on, the D4 light is bright. This only seems to happen with the car in gear because I have tried to leave the car in park with the hood open to see if there was anything strange happening, but the D4 light never dim. I know that the problem is not due to the radiator fan coming on because I have seen the radiator fan coming on and off without the D4 light dimming. This morning I hooked up a radar with a voltage measuring device to the cigarette lighter and see if the the voltage changes a lot when this happens. When the car started the voltage read about 14.2. When the D4 light dims the voltage read about 12.3. The car starts up fine every morning, even in cold weather so I don't know what the problem could be. Any comments on what you guys think is the problem is appreciated. Thanks in advance!

main70072

Any ideas?

Go90go

Check your grounds and see if either cleaning off the negative terminal of corrosion will help, or just running an extra ground to the frame from the battery.

~Cheers~

TexasHonda

It sounds normal to me. Honda/Acuras have a load detection circuit that will reduce the charge voltage to save fuel. I think this is what is causing your light to dim. I monitor my voltage all the time and mine works similarly, however I've never noticed D4 light dimming and brightening, but have noticed other lights doing same.

good luck

main70072

Thank you guys for the responses. I will keep those things in mind.

desired_speeds

hmm, seems like the dimming is pretty extreme. Check your grounds and the positive connector on the alternator to make sure its free of corrosion.

main70072

Yes the dimming is pretty extreme and even if i touch the pedal very light and let it go, the light will dim and come back bright. It is very sensitive. I am only afraid if I drive with the D4 light dim for a long time, the alternator will not put out enough to charge the battery. I will take your advice and check the positive connector on the alternator as soon as it gets warmer outside. Thanks!