On the way home from work today I noticed that my (stock)headlights get much brighter when I rev the motor. I know that the alternator works off of rpms but this is not the same. In all of my other rigs this is not the case... Does this happen w/ anyone else?
98 sr5 4runner v6 auto 4x4.

 

Check your battery it maybe gettin ready to take a dump.
other things to consider are are you running a booming stereo set up ? lights or any other electrical do dads that may draw a good amount of power off the battery?
Just a few things that come to mind
Daniel

 

All stock except a small CB I mounted in the ashtray location. The bat. is two years old. I guess that is just within the time frame I would start looking for trouble from it. If so that is the first time that 24months means 24 months....I have only replaced the battery once in my 91 truck. I thought it might be the alt. overcharging. I think I have heard of this happening, on the way to replacement. Is this true?

 

If you're talking about at idle your headlights are a little dimmer than at above idle, then I wouldn't worry about it. If you're saying they're not burning at their brightest at anything over 2000rpm, then you might have a potential problem somewhere in the system.

 

MY99 is correct.

It's so important to get a voltage and amperage gauges to determine the health of the electrical system.

Parts associated with dimming lights that fail are

> battery > alternator > wiring - connections

Cold weather will easily rob a healthy battery of cold cranking amps. It takes extra time to recharge the battery. This is one possible scenario that could explain what is happening.

 

Idaho,
try this quick trouble shoot,start the truck and disconnect the battery then with a volt meter check your volts at the cable terminal ends on mine it runs @ about 12.5 to 13 volts I say roughly anything under 12 yer probably getting ready to lose an alt anything above 13 roughly and yer more n likely over charging yer batt.
At the same time check your battery at the terminals you should be any where between 11.5 and 13 any thing below 11.5 would indicate the plates in the batt are starting to go bad,that is if the alt checks good.
Keep in mind the Japanese type veh in Japan is slightly different than stateside even in electrical. my numbers may very from yours slightly.
but by the most part it's the same animal
All in all I'm with My99 and amusement them.
Happy hunting
Daniel