Inspection Procedure 2

INSPECTION PROCEDURE 2: Insufficient Braking Power

DIAGNOSIS
STEP 1. Check whether the brake fluid is low, is the correct fluid (A/T fluid, engine oil, etc.) or is contaminated (debris, sand, etc.).
Q: Is there fault?
YES: Refill or replace with the specified brake fluid DOT 3 or DOT 4. Bleed the brakes if necessary. Then go to Step 7.
NO: Go to Step 2.

STEP 2. Check for spongy (not firm brakes).
1. With engine not running, depress the brake pedal rapidly several times to deplete booster vacuum reserve.
2. With the brake pedal fully released, depress the brake pedal slowly until it stops.
3. With a measuring stick (ruler, etc.) next to the brake pedal, depress the pedal firmly and measure the distance the pedal traveled.
Q: Is the distance greater than 20 mm (0.8 inch)?
YES: Bleed the brakes to remove air in the fluid. Then go to Step 7.
NO: Go to Step 3.

STEP 3. Check the brake booster function.
Q: Is there fault?
YES: Replace the brake booster. Then go to Step 7.
NO: Go to Step 4.

STEP 4. Check for pinched or restricted brake tube or hose.
Q: Is there a pinched or restricted brake tube or hose?
YES: Replace that complete section of brake tube or brake hose. Then go to Step 7.
NO: Go to Step 5.

STEP 5. Check for oil, water, etc., on the pad contact surfaces of all brakes.
Q: Is oil, water, etc., on the pad contact surface?
YES: Replace the part. Determine and repair the source/cause of foreign material. Recheck symptom. Then go to Step 7.
NO: Diagnosis is complete. If condition persists for vehicles without ABS, go to Step 6.

STEP 6. Check the proportioning valve operation.
Q: Is there fault?
YES: Replace the proportioning valve. Then go to Step 7.
NO: Go to Step 7.

STEP 7. Recheck symptom.
Q: Is the symptom eliminated?
YES: Diagnosis is complete.
NO: Start over at step 1. If a new symptom surfaces, refer to the appropriate symptom chart. Symptom Chart