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.

1988 Mazda 929 AutomaticFACTORY OEM SERVICE PROCEDURE

Pressure Regulator Control (PRC) Solenoid

Disconnect intake air temperature sensor on dynamic chamber. Connect a 3000 ohms resistor to sensor connector. Disconnect coolant temperature sensor. Connect a 200 ohms resistor to sensor connector.
Connect voltmeter between PRC solenoid Blue/Black wire and ground. With engine running, voltage should be less than 2.5 volts for 4 minutes after starting. After 4 minutes, voltage should be 12 volts. If not repair wiring or connection. See Fig 1 .

Fig 1: Checking Pressure Regulator Control Solenoid
Courtesy of MAZDA MOTORS CORP.
Disconnect vacuum hose from solenoid. Blow through port A. Ensure air exhausts through port B. See Fig 2 .
Disconnect 2 wire connector from solenoid. Connect 12 volts to one terminal and ground the other terminal of solenoid. Blow air though port A. Ensure air exhausts through air filter.

Fig 2: Pressure Regulator Control Solenoid

Courtesy of MAZDA MOTORS CORP.

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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