So whenever the batteries are going bad in my truck, the abs and parking brake lights do a second bulb check during a cold start. That is after waiting for the grid heater (glow plugs) to warm up it does this. Keep in mind I've owned this truck since new, and it's done this everytime I need new batteries. Now if the truck is warm enough to not need the grid heater, then the lights only do one initial bulb check. So what does that brief period of low voltage from starting up cause the two lights to come on and go out again?