Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
1995 Geo Prizm Base, AutomaticFACTORY OEM SERVICE PROCEDURE
Motor Testing
NOTE:
Test described is for operation of front motors. Rear motor can be tested in similar manner, except there will be only a slight pedal drop and rise (bump) during test.
- Turn ignition to LOCK position. Install Tech 1 with Mass Storage Cartridge (MSC). Turn on ignition, engine off. Pump brake pedal several times to deplete vacuum reserve. Depress and hold brake pedal.
- Using Tech 1, release one of the motors. Brake pedal should drop smoothly. As pedal drops, feedback current should momentarily drop to only a few amps (indicated motor movement) and then equalize to command current (6 amps). This indicates motor is no longer moving since piston has bottomed out.
- A rough or jumpy pedal movement indicates an intermittent motor connection. With brake pedal still depressed, apply the same motor. Brake pedal should smoothly rise back to the top of its travel. Feedback current should momentarily drop to a few amps, then quickly increase to command current (10 amps). This indicates motor is no longer moving since piston reached the top of its travel.
- If brake pedal does not move both up and down as indicated and no DTCs are present, monitor the feedback current closely while performing the test again. If feedback current is only a few amps, motor is free spinning. Separate motor pack from hydraulic unit to diagnose problem. See MOTOR PACK FUNCTION TEST .
Factory Service Tools
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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