While plowing my driveway tonight both the ABS and BRAKE idiot lights came on at the same time. The brakes continued to operate normally while I finished up my plowing.

What type of problem would cause both the ABS and BRAKE to both illuminate at the same time?

It's a 2004.5 Quad Cab Automatic 50K miles

(It may not be related but the Check Engine came on when I started it at work to get home this evening. I have a scanner and can pull that code.)
edit: The Check Engine code was P0514 - Battery Temperature Sensor Rationality

 

Also check your brake fluid level. When it is low the brake light will come on. Can you not check codes by turning the ignition on and off three times?

 

I grabbed my scanner. It was P0514 - Battery Temperature Sensor Rationality
(I updated the post above too with the info)

Brake fluid is Full, e-brake is off.

Other ideas?

 

My lights came on when my wheel speed sensor went out.

 

Try disconnecting the batteries for about 15 minutes. The re-connect them, clear the code and see if it comes back.

 

I never really looked at my 3rd gen, but that happened to my 2nd gen gasser.

 

When the crappy weather eases up here I'll look over the wiring to the wheel speed sensors, clean and dry their respective connectors. I read last night that moisture in the connectors could cause a problem as the ABS circuit is very resistance sensitive (plus I did hit a puddle in the passing lane on the highway last night)

Afterwards I'll do the Reset as recommended above.

I'll post up the results.

 

https://www.dieseltruckresource.com/...bs+brake+light

 

Just to follow up..
We finally had a day above freezing today so any snow or ice that may have gotten on a sensor would have melted. Fired up the truck today and the ABS and Brake lights went off after a few seconds.
All is good!

Thank you all for your help!

 

Just so you know for future reference, I have had the brake lights come on from time to time in similar conditions. I have had them come on while plowing or driving in deep snow. Sometimes, what will trigger the lights is a wide variation is wheel speed between either the front and rear wheels or even side to side on the front. The ABS ECU gets confused when wheels speeds don't agree by a certain margin and the rationality goes out the window. When this situation occurs, the lights will turn off on the next key cycle AND re-agreement of wheel speeds (reasonable rationality). In other words, starting the truck or key cycling alone is not enough. The truck must actually move after the key cycle in order for the ABS ECU to get its bearings again. There are no stored codes to my knowledge when these incidents occur.

 

Thank you for the additional information!
You explaination makes perfect sense since one frequently experiences wheel slip when plowing heavy snow in slippery conditions. What I was plowing was a very heavy wet snow and there was a layer of ice on the ground below the snow causing the wheels to slip frequently that night.