My rear brakes are locked up. What could be the problem

If the actuator is not working and you need to engage your 4x4 to get home, you can manually lock in your 4x4 system using the front axle's manual locking hubs (assuming your vehicle has manual locking hubs). Here are the steps to manually lock in your 4x4 system:

1. Locate the manual locking hubs on the front wheels of your vehicle. They are typically located at the center of the wheel hub, and will have a dial or lever that you can turn or pull to engage the hub.
2. Make sure your vehicle is in neutral, with the parking brake engaged.
3. Turn the dial or lever on each manual locking hub to the "lock" position. This will physically engage the front axle, allowing power to be transferred to the front wheels.
4. Engage your 4x4 by shifting the transfer case lever into the appropriate 4x4 mode (4-Hi or 4-Lo).
5. Test your 4x4 by driving slowly in a straight line. If you hear any grinding or feel any vibrations, stop immediately and check your manual locking hubs and 4x4 system.

It's important to note that driving in 4x4 mode on dry pavement can cause damage to your drivetrain, so be sure to disengage your 4x4 system and unlock your manual locking hubs once you're back on solid ground.

To override the parking brake on a 1993 F700, you will need to disengage the brake manually. Here are the steps to follow:

1. Locate the parking brake lever inside the cab of the vehicle. It is typically located near the driver's seat, on the floor or the dashboard.
2. Pull the parking brake lever up to the fully engaged position. This will disengage the brake and allow you to move the vehicle.
3. Start the engine and shift the vehicle into gear.
4. Slowly release the parking brake lever, allowing the brake to engage gradually. Do not release the lever too quickly, as this can cause the vehicle to lurch or jerk.
5. Slowly drive the vehicle, testing the brakes to make sure they are working properly. If you experience any problems or issues with the brakes, you may need to have them checked or repaired by a qualified mechanic.

Overall, to override the parking brake on a 1993 F700, you will need to disengage the brake manually by pulling up on the parking brake lever and releasing it gradually. Make sure to test the brakes before driving the vehicle to ensure they are functioning properly.

A parking brake (informally known as "emergency brake" or simply "e-brake") is a secondary brake system that uses brake cables to engage the rear brakes rather than the using the hydraulic brake system which actuates both the front and rear brakes. The brake cables are pulled by a ratcheting mechanism inside a cabin which can be a pull lever or a push pedal. In either case the mechanism must be able to release the cable tension. Although rare, a problem in this mechanism could prevent the ratchet from disengaging and in turn keep the parking brake engaged. A much more common problem however is with the cables or brakes themselves. Rust and corrosion that accumulates over time can cause the moving parts to bind and not release from their engaged position. To resolve, the binding parts must be moved back into their original resting position manually and then replaced with non-rusted/corroded parts. In some extreme cases it may be necessary to actually cut through a brake cable in order to release tension and make repairs. You can read more here: https://www.yourmechanic.com/services/adjust-parking-brake-cable

Seems like your emergency brake is engaged or stuck engaged

how long since you serviced the rear parking brake assembly

they do require periodic maintenance and lubrication

it could be 1 of 2 problems or both

1/ the parking brake cable for that wheel has seized from non use ( water will seep into the cable sleeving over time and cause rust to form, rust welding the cable to the inner metal sleeve )

2/ the parking brake assembly itself has seized in the wheel holding position .



the only true way to free up the assembly is to crawl under your vehicle , use a small length of a 2 x 4 and with a 5 pound sledge hammer , whack hard on the backing plate until the parking brake assembly releases

It is not unusual for the parking brake cable assembly to seize due to corrosion. Also, the rear brakes are self-adjusting when backing up and can eventually wind up by themselves until they lock up. Start by removing the rear wheels and checking the brake shoe assemblies. Due to the age of the vehicle, this can be quite a chore, as the brake adjuster may have to be manually backed off before the brake drums will come off. Also, if the brake cable is seized, you may have to remove/manually loosen it as well. It is a part that needs lubricating periodically so it works freely, and may need to be replaced.

Check all wheel sensors for broken wires, loose connectors or position of sensors in their mounting brackets.

Your front differential is what's called an "open" style. It's exactly the same as any differential found in any vehicle with non positraction rear wheel drive. In that type of diff, one wheel is always connected to the driveline through the small spider gears inside the carrier. When you are driving and there is power being applied through the driveshaft, power goes to the wheel with the least amount of traction, which is actually a bad way to do that but it seems to work fairly well except on ice or in mud.
Positraction differentials put fairly equal power to both wheels but you can't use them in the front end because they would make steering difficult. When you are cornering, the wheel on the outside of the turn needs to turn faster to keep up. A posi makes that difficult, a "locked rear" makes it near impossible. That's why you don't see them except in specialized off road vehicles (not in the front anyway).
The component that makes your front diff move the vehicle is the transfer case. On many GC's they use a quadratrack unit. That kind used a heat sensitive fluid coupler inside that locks up when the rear wheels start to slip. Those units can be identified by their shifter which only has three positions. Technically it's always in 4 wheel drive but it only comes on during slippage. The other manual kind has four positions and is engaged manually. Some early Cherokees (not GC's) and many wranglers use a vacuum diff lock up. So unless someone put one in there (lots of mods would be necessary) you have a normal open diff there and that's just how they act when off the ground.
If you cannot turn the wheel assembly at all, then there's a high probability that the hub bearing has frozen or the brake caliper piston is stuck in the applied position.
One interesting fact is that no vehicle is really four wheel drive...most only have one wheel in front and one in back actually moving the vehicle. If you are equipped with a rear posi diff, then essentially you have 3 wheel drive (with the exception of modified vehicles as I mentioned).

There are several conditions that can cause this to happen. You want to start out by checking the parking brake assembly, particularly the cable for the right rear or passenger side brake. Make certain the cable moves freely when the park brake is applied and released completely when the park brake is disengaged.
Next, remove the rear brake drum and check for any oil, grease or brake fluid contamination of the brake shoes. Any contamination of this type will cause the brake to hang up when applied.
If that checks good, make sure the brake system hardware if working properly and components have not dislodged from there installed position be sure there are no broken return springs or very rusted and weak components.
Generally what happens is a wheel cylinder begins to leak, contaminated the shoes and cause them to become sticky when the shoe contacts the drum or a return spring breaks or comes off for various reasons.
Check it out and let me know.
Regards,

sounds like your brake cable has broken or there is something damaged in the pedal assembly.........try pulling on the release handle and move the e-brake pedal back to its off position by hand at the same time.(you may have to tie it in this position to keep it up)If that doesnt work there is a sensor on the pedal assembly that you should be able to bypass by either disconecting the wire(1 wire system) or connecting the two wires together (2 wire system)Especially if your truck is a standard the e-brake is an important safety feature,so if these steps fix the light and dinging problem you should still take the steps to have it repaired.
hope this helps.........Good Luck!