2006 ~ Noticed the car lights (head lights only) flickering off for a few seconds while driving at night, took it in and they re-set the computer, still is flickering. Without spending 4 hours in labor for them to check every wire, any suggestions?
Have the battery and charging system thoroughly tested.
Check for loose grounds.
If the battery is over 5 years old, replace it. It’s on its last legs.
Flickering is usually due to a poor connection. It can be a defective switch or relay but most often it is a bad ground. A bad ground strap between the engine and the body can cause this, but most modern cars have multiple ground straps so you don’t see this very often.
The ground for the headlights themselves can be either under the dash or under the hood. Some systems provide hot directly to the bulb, then the return is routed through the firewall, to the switch and then to ground. Other systems provide the hot to the bulb and the return to a relay under the hood. when the switch is turned on, power is sent to the coil of the relay where the contacts them make and send the return to ground there. The second system is most common in the newest cars and any car with an automatic headlight system.
A bad battery can cause the headlights to dim under certain conditions, but it does not usually cause flicker, not that it can’t, its just not usual. I do agree that if the battery is over 5 years old, you might want to consider a new one.