What's up with brake/abs?

[Lordsman]

I noticed my brake/abs light coming on sometimes when stopped at a light, as soon as I let off in the brake pedal it would go away. Then about a month later I'd be driving along(not stopping) and they would light up and turn off very quickly. Now this. I started it up this morning to go to work. Fired up fine, grid heaters cycling normally(didn't have it plugged in overnight), let it idle for 5 minutes, and backed out of the driveway. While stopping to shift from reverse to drive the brake/abs light came on for a few seconds and the radio shut off. Then as the lights went out the radio would come back on. This continued(4-5 times) as I drove along until I got frustrated and just turned the radio off. As the truck got fully warmed up the problem went away. This is real weird as I've read about this problem before, but never with the radio going with it. Anyone had this happen to them? I have a 1993 service book so I can start to diagnose, but I figure I'd chime in here too.

 

[CRWilliams]

Just a thought, but if the lights are coming on and the radio going off when the grid heater is on maybe your battery is getting weak(or the alternator) and the voltage is dropping too low when the grid heater is on. This would cause alot of the electrical system to act like you had turned the key off and then back on. Sitting at the stop light with your foot on the brake and having the light come on is probably the power booster getting weak, small leak. Mine is doing this right now and the power assist goes away sitting at the light. Boosters are EXPENSIVE though, I need to change mine soon it is getting pretty bad.

 

[JBrookshire]

had this problem

This happen to me before while going down the road. The raido would short out then finally the truck quit. Come to find out one of the min FUSELINKS rotted apart and lost power to th pump or some thing Maby this would help.

 

[Lordsman]

Vacuum Check

Well I did a vacuum check. Pulled the hose off the switch at fenderwall and started it up, vacuum went to 23 inches. Pressed on brake pedal and it decreased to 14 inches. Pedal feels mushy though. When pumping brake pedal vacuum can decrease to 6 inches. After I pump and hold pedal down vacuum stays at 14 inches. Checked brake fluid rear reservoir was 1/2 full, so filled to 1/2" from top. Seems I have air in the lines somwhere, so that needs to be fixed. Need to do a full blown test of everything, I'd hate to lose brakes when I need to stop. Yes, I've noticed corrosion at fusible links, looks like battery acid got to them at one time. I had to bypass the one that fed the blower fuse and power windows. I better look closer.

Where is the voltage regulator? Looked through service book and it didn't mention one.

Thanks for the input I'll keep you posted.