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 MANUALSMAZDA2005MX-5 MIATA L4-1.8L DOHCREPAIR AND DIAGNOSISPOWERTRAIN MANAGEMENTCOMPUTERS AND CONTROL SYSTEMSCAMSHAFT POSITION SENSORTESTING AND INSPECTION
2005 Mazda MX-5 Miata L4-1.8L DOHC
Camshaft Position Sensor: Testing and Inspection
2005 Mazda MX-5 Miata L4-1.8L DOHCSECTION Testing and Inspection
CAMSHAFT POSITION (CMP) SENSOR INSPECTION
Visual Inspection
1. Remove the CMP sensor. (See CAMSHAFT POSITION (CMP) SENSOR REMOVAL/ INSTALLATION [BP, BP WITH TC].)
2. Make sure that the CMP sensor is free of any metallic shavings or particles.
- If metallic shavings or particles are found on the sensor, clean them off.
3. Install the CMP sensor. (See CAMSHAFT POSITION (CMP) SENSOR REMOVAL/INSTALLATION [BP, BP WITH TC].)
Wave Profile Inspection
1. Remove the PCM. (See PCM REMOVAL/INSTALLATION [BP, BP WITH TC].)
2. Connect WDS or equivalent to DLC-2 connector.
3. Connect oscilloscope test leads to the following PCM connector terminals.
- (+)lead:PCM terminal 3V
- (-)lead:PCM terminal 4A
4. Start the engine.
5. Monitor RPM PID.
6. Inspect wave profile when idling engine.
- If wave profile or voltage are out of specifications, carry out the "Circuit Open/Short Inspection".
- PCM terminal: 3V(+) <=> 4A(-)
- Oscilloscope setting: 2.0V/DIV(Y), 20ms/ DIV(X), DC range
- Vehicle condition: Idling
Circuit Open/Short Inspection
1. Remove the PCM. (See PCM REMOVAL/INSTALLATION [BP, BP WITH TC].)
2. Inspect the following wiring harnesses for an open or short circuit by probing the applicable sensor and PCM 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 CMP sensor.
Open circuit
- CMP signal circuit (CMP sensor connector terminal B and PCM connector terminal 3V)
- Power circuit (CMP sensor connector terminal A and main relay terminal D through common connector)
- GND circuit (CMP sensor connector terminal C and PCM connector terminal 4A)
Short circuit
- CMP signal circuit (CMP sensor connector terminal B and PCM connector terminal 3V to GND)
- Power circuit (CMP sensor connector terminal A and main relay terminal D through common connector to GND)
3. Reconnect the CMP sensor connector.
4. Inspect the protrusion of camshaft (intake side) for damage and cracks.
Visual Inspection
1. Remove the CMP sensor. (See CAMSHAFT POSITION (CMP) SENSOR REMOVAL/ INSTALLATION [BP, BP WITH TC].)
2. Make sure that the CMP sensor is free of any metallic shavings or particles.
- If metallic shavings or particles are found on the sensor, clean them off.
3. Install the CMP sensor. (See CAMSHAFT POSITION (CMP) SENSOR REMOVAL/INSTALLATION [BP, BP WITH TC].)
Wave Profile Inspection
1. Remove the PCM. (See PCM REMOVAL/INSTALLATION [BP, BP WITH TC].)
2. Connect WDS or equivalent to DLC-2 connector.
3. Connect oscilloscope test leads to the following PCM connector terminals.
- (+)lead:PCM terminal 3V
- (-)lead:PCM terminal 4A
4. Start the engine.
5. Monitor RPM PID.
6. Inspect wave profile when idling engine.
- If wave profile or voltage are out of specifications, carry out the "Circuit Open/Short Inspection".
- PCM terminal: 3V(+) <=> 4A(-)
- Oscilloscope setting: 2.0V/DIV(Y), 20ms/ DIV(X), DC range
- Vehicle condition: Idling
Circuit Open/Short Inspection
1. Remove the PCM. (See PCM REMOVAL/INSTALLATION [BP, BP WITH TC].)
2. Inspect the following wiring harnesses for an open or short circuit by probing the applicable sensor and PCM 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 CMP sensor.
Open circuit
- CMP signal circuit (CMP sensor connector terminal B and PCM connector terminal 3V)
- Power circuit (CMP sensor connector terminal A and main relay terminal D through common connector)
- GND circuit (CMP sensor connector terminal C and PCM connector terminal 4A)
Short circuit
- CMP signal circuit (CMP sensor connector terminal B and PCM connector terminal 3V to GND)
- Power circuit (CMP sensor connector terminal A and main relay terminal D through common connector to GND)
3. Reconnect the CMP sensor connector.
4. Inspect the protrusion of camshaft (intake side) for damage and cracks.
RENDER: 1.0x
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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.