Headlights dim when using accessories.....

[byez]

Could this mean the battery is going out or is it common or is the alternator weak?

Toyota Highlander with 90km. Lights dim slightly if i use the windows or use the door locks etc.

 

[byez]

fyi no subs or aftermarket stereo

 

[Quest]

With 90k (assuming that you mean 90,000kms and not just 90kms) on your odo, check your battery first before you start jumping into conclusions.

I currently have a Camry Vee6 LE with a 14+yr old Denso alternator (original, never been replaced) running on it past 220,000kms and it is still running strong. Even if you ended up with a Mitsu or Hitachi alternator, they should be more than capable in providing all the necessary juice for all your electrical needs + battery charging and still able to provide extremely long, reliable service life.

Q.

 

[Donald]

I would guess the main positive wire off the starter solenoid (that feeds all of the vehicle except the starter itself) is either undersized or the connection is slightly corroded or loose.

Get a DVM and measure voltage across the battery when this happens and also across a 12V wire in the dash, like the cigarette lighter.

If your battery was going (south) you car would not start. The lights and window motor do not take anything close to what the starter takes.

Even if the alternator was going (but car still started), the battery would make up for whatever the alternator could not put out, at least for a period of time.

 

[deepsquat]

first clean up the battery posts..then check ..still dimming ...I really think alternator if you have a volt meter you can check the
voltage with car running and accessories on ..if you don't get a t least 13.2 volts ..it's your alternator ..if with car not running you don't have around 12.6 - 13 volts..it is battery .....easiest
...just have it tested for free

 

[BearZDefect]

byez, it might help if you specify when this dimming happens. Here are a few questions:

1. What is the model year of the vehicle?

2. Is this something new that didn't happen before?

3. When do they dim? Engine off? Engine at idle? Engine running faster, say 2,000rpm?

Many alternators do not put out much electricity at a low idle.

 

[dwendt44]

I've heard of brushes sticking resulting in lowered output.
Just a thought.

 

[JohnBrowning]

If you head lights are dimming check all the ground wires first. Then check the main line comeing off the alternator. Then check the batter cables for corrsion then check the headlight harness and then the power distribution block.... If you get corrsion on any of these it can have you chaseing your tail for batter and alternator issues when they are both fine... These situatuions will prevent the battery from getting a complete charge or dischargeing it's power when needed... Wire is alot like plumping anything that interupts the free flow of elctron's is going to cause all kinds of issues!When I worked at a part's store you wouldnot belive how many times I would ask someone if they had checked their wires!!! Seeing checking wires is a pain int he arse but changeing a battery or alternator is a job a monkey could do blindfolded so everyone would want their battery or alternator tested!!!! I can tell you inthe year I worked their I onlyhad one Denso Alternator from an import of domestic like Dodge test bad! One!!!Most of them were rather old and covered in sludge and such....It got tot he point that when I say it was a denso I could almost gurantee that it was a wire issue..

 

[brianl703]

Find someone with a VAT to load test the battery and the alternator. In the USA all the Autozone stores have them.