How to Repair Electric Brakes

Any automotive repair involving the braking system must be done according to precise directions. Close attention to detail and the ability to do both mechanical and electrical work are needed to repair electric brakes. Testing will involve using a voltmeter and understanding the operation of the brake shoes, calipers and solenoids. This repair involves the electrical system only and does not deal with replacing brake shoes or pads. The average weekend mechanic can perform this repair in about three hours.

Instructions

1

Put on safety glasses. Locate the electric brake switch, usually under the hood connected to the brake line or the brake pedal linkage, unlike hydraulic brakes which connect to the master cylinder and use fluid. Inspect the two or four wires connected to it and make sure they are tightly secured and in good condition.

2

Set a voltmeter to 12-volts and place the positive lead from the voltmeter onto one of the terminals on the brake switch using its alligator clip and the negative lead onto a good ground source connected to the negative side of the battery. Move the positive voltmeter lead to the other terminal if the voltmeter is showing 12 volts or any voltage.

3

Read the voltmeter as a helper holds the brake pedal down for about 10 seconds. The voltmeter should read 12 volts.

4

Reverse the positive and negative lead locations on the voltmeter if no voltage is displayed then once again ask your helper to operate the brake pedal. Replace the brake switch if no voltage is read while the brake pedal is operated.

5

Remove the hubcap and very slightly loosen the lug nuts on the problem wheel if the brake switch worked correctly. Place the jack under the axle and raise the wheel. Remove the lug nuts all the way then remove the wheel from the hub.

6

Detach the brake drum, if so equipped, and any plates or covers blocking access to the solenoid(s). Do not remove the solenoids. Place the voltmeter's positive lead onto the positive terminal on the solenoid and the negative lead on the negative terminal and instruct your helper operate the brakes. Repeat the procedure at each solenoid and each wheel if the voltmeter reads 12 volts and the solenoid operates properly. Repeat the procedure until all solenoids have been tested.

7

Replace any solenoid that does not operate if the voltmeter displayed 12 volts on its terminals when the brake pedal was held down for 10 seconds. Check the connections and wiring between the solenoid and the brake switch if no voltage was displayed when the brake pedal was depressed.

8

Rotate the raised wheel by hand after all tests and repairs have been completed, and have your helper operate the brake pedal for at least 10 seconds, observing if the wheel stops abruptly when the brake is applied. Reassemble all components that were removed and test the other wheels' stopping ability in the same manner. Repeat the electrical tests and repairs to any brake solenoid that does not work properly.