I've searched this board for similar topics, read them, but still wanted to get opinions on my situation. First off, I have not attempted to fix anything yet.

Everyday driver, '74 F-100 302 w/ (stock, I'm assuming)power brakes. Have owned it since May. When I first bought it from a coworker of mine, the parking brake was real weak so I adjusted it. Threw that in there just in case it mattered.

About a month after I bought the truck the brakes indicator light would come on sporadically. It stopped doing it after about three weeks. The light came on again about three weeks ago and has stayed on since. Until last week, when I read it on the forum, I thought it was my parking brake light coming on even when I knew it was off. I did open up my brake fluid res and it is full. When the light was on I did feel that the braking power was alot less than I had been used to. I started making plans to change my brakes this weekend but then I read all the information on the board and in my Haynes book that makes me want to go further into diagnosing the problem.

I remember reading somewhere about how to reset the brakes by holding the brakes down hard. This is what happened this morning. I work the graveyard shift (in AZ so it hasn't been very cold) and when I went and got into my truck I turned the truck to ACC and then pushed the brake down hard for about 30 seconds or more. Started the truck up and the light was still on. Got home, and picked up a letter that I had to mail. The truck had sat for about 20 mins. went to the post office 1.5 miles away. The light was on. When I got back into the truck and started it up the brakes light was off and the brakes felt a little firmer. To test it out, on my way home, I would lock the brakes up a couple of times at about 5 to 10 mph and they seemed to lock up fine.

It's been another 20 minutes or so while I made some phone calls and wrote most of this post but I just went out and turned it on again and the light is still off. I am still going to change my pads (I'm pretty sure it's pads) this weekend but want some feedback about what you think my problem could be or some things I should try.

Thanks for any and all input

Joel

 

Hmmm!

The only thing I could comment on is whenever you plan to replace the brake pads/shoes >Make sure you re-surface the rotors/drums and always replace them in pairs (Never > Just one side)

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I believe your problem is in the master cylinder. It is leaking between the front and rear systems. This causes a piston in the combination valve to move to one side and light the warning light. I would replace it myself before it fails when you least expect it.

 

Every time the brake light has come on on me it was the master cylinder. The light idicates a difference in pressure between the front and rear system. Theoretically if you had a leak on one system (rear drum cylinder, disk caliper, line etc)then the light should come on. If on inspection you don't find a brake fluid leak then I would suspect a failure internal to the master cylinder allowing less pressure on one system. I would replace the MC asap. This condition means you are using only 2 brakes (of the 4 wheels) to stop. They could easily overheat and fail.