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.
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HOMESERVICE MANUALSMAZDA1999PROTEGE LX L4-1.6L DOHCREPAIR AND DIAGNOSISPOWERTRAIN MANAGEMENTCOMPUTERS AND CONTROL SYSTEMSMAIN RELAY (COMPUTER/FUEL SYSTEM)TESTING AND INSPECTIONMAIN RELAY INSPECTION
1999 Mazda Protege LX L4-1.6L DOHC
Main Relay Inspection
1999 Mazda Protege LX L4-1.6L DOHCSECTION Main Relay Inspection
NOTE: Perform the following test only when directed.
1. Disconnect the negative battery cable.
2. Remove the main relay.
3. Inspect for continuity between terminals of the relay using an ohmmeter.
Specification
- If not as specified, replace the main relay.
- If the main relay is okay, but PCM terminal 71 or 97 voltage is out of specification, inspect as follows.
1. Remove the PCM.
2. Connect the SST (104 Pin Breakout Box) to the PCM as shown.
3. Tighten the connector attaching screw.
Tightening torque
7.9 - 10.7 Nm (80 - 110 kg.cm, 69.5 - 95.4 in.lb)
4. Inspect for an open or short circuit in the following wiring harnesses by probing the applicable sensor and SST (104 Pin Breakout Box) terminals with ohmmeter leads.
- If there is an open or short circuit, repair or replace wiring harnesses.
- If there is no open or short circuit, replace the main relay.
Open circuit
- Main relay power supply circuit (Main relay connector terminal A and ignition switch (IG1) connector through common connector)
- PCM power supply circuit (Main relay terminal C and battery positive terminal through common connector)
- Ground circuit (Main relay connector terminal B and Ground through common connector)
Short circuit
- Main relay power supply circuit (Main relay connector terminal A and ignition switch (IG1) connector through common connector to Ground)
- PCM power supply circuit (Main relay connector terminal C and battery positive terminal through common connector to Ground)
4. Reconnect the main relay.
1. Disconnect the negative battery cable.
2. Remove the main relay.
3. Inspect for continuity between terminals of the relay using an ohmmeter.
Specification
- If not as specified, replace the main relay.
- If the main relay is okay, but PCM terminal 71 or 97 voltage is out of specification, inspect as follows.
1. Remove the PCM.
2. Connect the SST (104 Pin Breakout Box) to the PCM as shown.
3. Tighten the connector attaching screw.
Tightening torque
7.9 - 10.7 Nm (80 - 110 kg.cm, 69.5 - 95.4 in.lb)
4. Inspect for an open or short circuit in the following wiring harnesses by probing the applicable sensor and SST (104 Pin Breakout Box) terminals with ohmmeter leads.
- If there is an open or short circuit, repair or replace wiring harnesses.
- If there is no open or short circuit, replace the main relay.
Open circuit
- Main relay power supply circuit (Main relay connector terminal A and ignition switch (IG1) connector through common connector)
- PCM power supply circuit (Main relay terminal C and battery positive terminal through common connector)
- Ground circuit (Main relay connector terminal B and Ground through common connector)
Short circuit
- Main relay power supply circuit (Main relay connector terminal A and ignition switch (IG1) connector through common connector to Ground)
- PCM power supply circuit (Main relay connector terminal C and battery positive terminal through common connector to Ground)
4. Reconnect the main relay.
RENDER: 1.0x
NO RELATED
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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.