Testing the accumulator is a very simple. Anyone can do it, no mechanic needed.

Test number 1:

1. Open the hood so you can hear the pump motor run.
    
2. Turn the key ON ....DO NOT START THE ENGINE.
    
3. Listen to the brake pump running and wait until it stops.
    
4. Push the brake pedal like you are making a normal stop. Release and push the pedal again until you hear the pump start.

• A bad accumulator will cause the pump to start with one or two pumps.
• A good accumulator might give you 5-8 pumps before the pump starts.

The next test will verify the results of the first test.

Test number 2:

1. Clean the side of the brake fluid reservoir so you can see the fluid level.
    
2. Put a piece of masking tape on the side of the reservoir so you can mark the fluid level.
    
3. With the key OFF....... pump the brake pedal until it gets hard.
    
4. Mark the level of the brake fluid in the reservoir. It should be to the full mark.
   

   If the fluid level is near the cap there is too much fluid in the reservoir. Remove any excess fluid before marking the tape.

5. Turn the key ON and wait until the brake pump stops (the amount of time it takes for the pump to stop is also a clue, very short or very long run time is bad).
    
6. When the pump stops, mark the fluid level on the tape and measure the difference between the two marks. The amount of fluid reflects the amount of fluid going into the accumulator.

If the fluid level change is 1/2 inch or more, your accumulator is on its last legs.

Also note: a totally defective accumulator will not displace fluid so the level will stay the same.

If you get inconsistent results when repeating the test above, it may be because the pressure switch is going bad. Jim Finn suggests pulling the pressure switch connector and looking for moisture. If it is damp, brake fluid is leaking past the seals and the switch is failing.