light problem

just started my truck up this morning and noticed all the lights in my truck are quickly dimming about every 3 4 seconds does anyone know why this may be happening its an 09 I bought new never had any issues before

 

Get ur battery checked

 

In older cars I've owned, dim, pulsating headlights were usually caused by an alternator starting to go bad or a voltage regulator starting to die. This was back when the regulators were a separate part. Now I believe the Tacoma, like many others, has the regulator built-in to the alternator. I'd start with checking both the alternator and the battery.

 

Stop by a parts store and have them check your charging system. Free

 

Probably your battery