Hi jimmy25. I'm using a 2001 book but I think it's the same circuit. I didn't notice that they're showing fuses for brakes in two different locations. The main fuse for the brake lights is listed as "Underhood Junction Block (near battery)". It's hot at all times and is a 20 amp labeled "Stop LPS". It feeds 12 volts to the orange wire on the brake light switch. When you press the pedal, the 12 volts must also show up on the white wire.
That white wire goes to the brake lights, AND it goes through a different 10 amp fuse, also by the battery, for the cruise control cancel signal. The only diagram I can find is for the cruise control, but I think that will provide for a nice clue. There's six pages of diagnostic information for that system. I don't have that much time left in my life to read all of that if I don't have to, but if I remember correctly, that circuit from the cruise control module needs to see the path to ground through the brake light bulbs for it to allow operation of the cruise control. Said another way, if the wiring from the module to the brake light bulbs is good, including the grounds, the cruise control should work. If you turn THAT around, what I'm trying to say is if the cruise control works, the wiring to the lights is ok. You need to check for the presence of 12 volts on the orange wire with a test light or cheap digital voltmeter.
There is no reference in my diagram to a brake light relay. That is most likely for part of the trailer towing package and is not directly related to the brake lights.
Sunday, April 4th, 2010 AT 6:39 PM