1984 Toyota Pickup BRAKES "LOCKING UP"

Tiny
BUCKWHEAT615
  • MEMBER
  • 1984 TOYOTA PICKUP
  • 4 CYL
  • 2WD
  • MANUAL
  • 89,500 MILES
SINCE IT HAS TURNED COLD AND WITH HIGH HUMIDITY, I THINK THE REAR BRAKES, WHICH APPEAR TO BE DRUM BRAKES ARE LOCKING UP. THE FIRST TIME I HAD GONE ABOUT FIVE MILES AND WAS ABOUT 3 MILES FROM HOME. I PULLED INTO A SERVICE STATION TO GET GAS AND IT FELT LIKE SOMEONE HAD PULLED ON THE EMERGENCY BRAKES. I WAS BARELY ABLE TO GET INTO A PARKING PLACE, AS THE TRUCK WAS IMMOVABLE. THE REAR END WOULD RIDE UP AND THE TRANSMISSION WOULD LET ENGINE REV UP. I CALLED A TOW TRUCK WHICH TOOK IT TO A MECHANIC AND THEY COULDN'T FIND ANYTHING WRONG THAT THE BRAKES APPARENTLY DRIED OUT. AFTER THAT I HAD TO GO FARTHER AND I LIGHTLY HELD THE BRAKES WHILE MOVING TO TRY TO HEAT THEM UP AND NOT FREEZE UP AGAIN. THAT WAS ABOUT A 25 MI. ROUND TRIP AND MY STRATEGY SEEMED TO WORK. THE NEXT TIME I MADE A SHORTER DRIVE, I TRIED HEATING THE SHOES AGAIN BUT THEY LOCKED UP JUST OUTSIDE A GROCERY STORE AND I GOT STUCK IN TRAFFIC. I HAD TO GET A TOW TRUCK AGAIN AND BY THE TIME I GOT HOME THE VEHICLE WAS DRIVABLE. THE TOW TRUCK DRIVER PULLED THE CAR WITH THE REAR WHEELS ON HIS DOLLY AS HE HAD ASSUMED, FROM WHAT I TOLD HIM, THAT IT WAS THE REAR WHEELS THAT WERE LOCKING UP. I'M WONDERING IF THERE IS SOME KIND OF SPRAY I COULD USE OR IF JUST CHANGE THE SHOES AND RESURFACE THE DRUMS WILL CURE THIS.
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Friday, December 19th, 2008 AT 2:33 PM

6 Replies

Tiny
JASONRAY
  • MEMBER
NO, that's not going to cure your problem. Something is causing the rear shoes to NOT release. First, we need to determine whether it's BOTH or ONE rear wheel locking up. If one's doing it, it could feel like both. To determine this, you'll need to catch it when it's happening and, using a floor jack, raise the rear wheels off the ground. See if either wheel will turn. If it's only ONE, you'll need to remove the drum and inspect. If it's BOTH, we need to start looking towards the Master Cylinder, perhaps. The M/C is designed to release a small amount when the pedal is released so the pads/shoes don't continually ride against the rotors/drums so much they get hot. If it fails, it could be holding the shoes out and not release them at all. The more you use them, the tighter they get. Start with this advice and see where it gets you. Repost and we'll keep trying
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Saturday, December 20th, 2008 AT 2:27 PM
Tiny
BUCKWHEAT615
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Thank you Jason you have helped a bunch. My name is Gene and I am the original poster. As I'm disabled and don't have a floor jack and jack stands, I probably won't be able to do anything until January 2009.

I got the truck from my daughter who had it two years. I have had it six years. During this time the brake warning light on the dash has been on. Since the brakes appeared to be working and jiggling the parking brake did not make the light go out I have just ignored it. Is there a sensor from the M/C to the warning light? If so can I disconnect it and see if the light goes out? And if it goes out would that indicate the need for a replacement M/C? The levels are fine in the M/C but I don't know if the brake fluid has lost its useful life. THANKS AGAIN!

GENE -- BUCKWHEAT615
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Monday, December 22nd, 2008 AT 1:48 PM
Tiny
JASONRAY
  • MEMBER
The brake light on the dash is possibly turned on by either the proportioning valve or a fluid level sensor. Even if there's enough fluid in the reservoir, the sensor coud still be turning the light on. See if there's an electrical connector at the master cylinder. If so, remove the cap and, using a small pick or screwdriver, poke the little plastic plunger a couple of times and see if it's possibly stuck all the way down. If so, that'll turn the light on. You may be able to free it up so that it'll float again and the light may go off. If there's no connector at the M/C, the the Proportioning Valve is probably turning the light on. It works on a fairly simple concept. This is where the amount of fluid to the front and rear brakes is determined. You do about 80% of the braking with the front and 20 with the rear. There's a little plunger inside the valve. If, say, there's some air in the rear brakes, when you press the brake pedal, the plunger in the valve will move that direction in it's housing since pressure will only build on the front brakes(since there's NO AIR in our scenario). The pressure on the front brake lines pushes the plunger away and towards the rear side. A switch is mounted to the top of the valve that reaches inside to the plunger. If it gets 'off center', the switch closes and the light comes on. Depending on how it's wired up from the factory, you may be able to unplug it and the light go out. This valve is sometimes hard to reach, though. They're usually hidden on the frame somewhere under the M/C. Good luck.
And, Gene, if there's anything else I can help you with, let me know. I'll be ready and willing.
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Monday, December 22nd, 2008 AT 6:33 PM
Tiny
BUCKWHEAT615
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The ssi from Gene the original poster. Jason Thanks again for the new reply and the response time. I still need to do what you suggested in your first response, which prompted me to give you more information on the possible problems or additional problems.

I checked for wires to the M/C and their was a group attached to the middle of the cap. Also I had mentioned before that I had checked the levels and the large resevoir was above min, so I added some fluiid.

This is a two seperate resevoir system and the small one did not have any min. - Max. Indicators but was below a line similar to one on the big resevior, so I added some to it also.

Additionally there is 2 wires connected to the large resevoir cap that has what looks like two seperate in line fuse holders. I couldn't get them loose because of the way it is closed. I traced one of them to what looks like a resistor block mounted on the base of the coil, or it might be a ground.

There is a slew of brake lines and under the larger resevior is a housing that looks like it could hold a plunger or valve.

The floats in the resevoirs are just free floating with nothing attached to them. I assume when the brake pedal is pressed the floats rise up to perform a function that I don't know.

THANKS AGAIN! MEERY CHRISTMAS AND A HAPPY NEW YEAR!

GENE
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Tuesday, December 23rd, 2008 AT 3:04 PM
Tiny
JASONRAY
  • MEMBER
The wires going to the cap on the M/C should be the level switch. There should be a float attached to it somewhere. If it's come apart and is still in the fluid when you remove the cap, that may be your problem with the light.

I just re-read the original post. Have we gotten away from the brakes locking up? Is that still happening? If so, I have a few ideas that will determine what's causing it. Repost again and let me know. Hopefully we can get to the bottom of all this without you spending too much money. Maybe you can buy a loved one a nice gift for Christmas instead of spending it on your truck. Good luck and Merry Christmas. I'll be waiting to hear back from you.
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Wednesday, December 24th, 2008 AT 5:25 PM
Tiny
BUCKWHEAT615
  • MEMBER
12-25-2008

JASON--Hope you had a good Christmas. Your last post answered my unasked question (would low brake fluid be causing the warning light and the locking up?) The floats are broken. They don't have anything connecting to the wires on the resevoir cap. So that's probably the warning light problem. If you will re-read my previous psots you will see that I explained that I wouldn't be able to follow your tips in your first reply until January 2009 because that's when I get my disability check.

So no I have not done the initial trouble shooting that you reccommended in your first reply. I plan to do that and get back to you. I was just trying to see if there was a link to the "locking up" and the brake warning light. So THANKS again -- for the prompt replies and I will also start donating more in January. If you have to work after Christmas I hope you can stay warm -- and to you and all your gang HAPPY NEW YEAR!

GOD'S BLESSING'S to YOU ALL AND GOOD DAY AND GOOD NIGHT!

Gene Israel formerly from New Mexico -- now from Franklin Tn. (Near Nashville)
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Thursday, December 25th, 2008 AT 12:01 AM

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