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Home >> Mazda >> 2010 >> 3 L4-2.0L >> Repair and Diagnosis >> Powertrain Management >> Computers and Control Systems >> Testing and Inspection >> Component Tests and General Diagnostics >> Part 1

Part 1




ENGINE CONTROL SYSTEM OPERATION INSPECTION [LF, L5]

Input Signal System Inspection Procedure

1. Find an irregular signal.

2. Locate source.

3. Repair or replace the malfunctioning part.

4. Confirm that the irregular signal is no longer detected.

Finding irregular signals

While referring to On-Board Diagnostic Test, use the PID/DATA monitor and record function to inspect the input signal system relating to the problem.
1. Start the engine and idle the vehicle. You can assume that any signals that are out of specification by a wide margin are irregular.

2. When recreating the problem, any sudden change in monitor input signals that is not intentionally created by the driver can be determined as irregular.

Locating the source of unusual signals

CAUTION:
- Compare the M-MDS monitor voltage with the measurement voltage using the digital measurement system function. If you use another tester, misreading may occur.
- When measuring voltage, attach the tester ground to the ground of the PCM that is being tested, or to the engine itself. If this is not performed, the measured voltage and actual voltage may differ.
- After connecting the pin to a waterproof coupler, confirming continuity and measuring the voltage, inspect the waterproof connector for cracks. If there are any, use sealant to fix them. Failure to do this may result in deterioration of the wiring harness or terminal from water damage, leading to problems with the vehicle.

Thermistor type (IAT sensor and ECT sensor No.1, No.2)





Input signal system inspection for thermistor type

1. When an irregular signal is detected, measure the #1 PCM terminal voltage.

- If the #1 terminal voltage and the M-MDS monitor voltage are the same, proceed to the next step.
- If there is a difference of 0.5 V or more, inspect the following points concerning the PCM connector:

- Female terminal opening loose
- Coupler (pin holder) damage
- Pin discoloration (blackness)
- Harness/pin crimp is loose or disconnected

2. Measure the #2 sensor terminal voltage.

- If there is a 0.5 V or more difference between the sensor and the M-MDS voltages, inspect the wiring harness for open or short circuits.
- If the sensor and the M-MDS voltages are the same, inspect the following points concerning the sensor connector:

- Female terminal opening is loose
- Coupler (pin holder) damage
- Pin discoloration (blackness)
- Harness/pin crimp is loose or disconnected
- If there are no problems, proceed to next investigation below.

GND system inspection for thermistor type

- Confirm that terminal sensor #3 is at 0 V.

- If it is at 0 V, inspect the sensor. If necessary, replace the sensor.
- If not, inspect for the following:

- Open circuit in wiring harness
- Female terminal opening is loose
- Coupler (pin holder) damage
- Pin discoloration (blackness)
- Harness/pin crimp is loose or disconnected

Main Relay Operation Inspection

1. Verify that the main relay clicks when the ignition is switched to ON and off.

- If there is no operation sound, inspect the following:

- Main relay Relay Inspection
- Harness and connector between ignition switch*1/relay block*2 and main relay
- Harness and connector between PCM terminal 1Q and main relay terminal B

*1
Vehicles without advanced keyless entry and push button start system
*2
Vehicles with advanced keyless entry and push button start system

Intake Manifold Vacuum Inspection

1. Verify air intake hoses are installed properly.

2. Start the engine and run it at idle.

3. Disconnect the vacuum hose between the intake manifold and purge solenoid valve from the intake manifold side.

4. Connect a vacuum gauge to the intake manifold and measure the intake manifold vacuum.

- If not as specified, inspect the following:

Specification
- LF: More than 68 kPa {510 mmHg, 20 inHg}
- L5: More than 70 kPa {525 mmHg, 21 inHg}

NOTE:
- Air suction can be located by engine speed change when lubricant is sprayed on the area where suction is occurring.

- Air suction at throttle body, intake manifold and PCV valve installation points
- EGR valve (stuck open)
- Fuel injector insulator
- Engine compression Testing and Inspection

Electronic Throttle Control System Inspection

Engine coolant temperature compensation inspection

1. Connect the M-MDS to the DLC-2.

2. Access the following PIDs:

- ECT1
- ECT2
- IAT
- RPM

3. Verify that the engine is cold, then start the engine.

4. Verify that the engine speed decreases as the engine warms up.

- If the engine speed does not decrease or decreases slowly, inspect the following:

- ECT sensor No.1, No.2 and related wiring harness Testing and Inspection
- Electronic throttle body and related wiring harness Testing and Inspection

Load compensation inspection

1. Start the engine and idle it.

2. Connect the M-MDS to the DLC-2.

3. Verify that P0506:00 or P0507:00 is not displayed.

- If P0506:00 or P0507:00 are displayed, perform DTC inspection. P0506 or P0507

4. Access the RPM PID.
NOTE:
- Excludes temporary idle speed drop just after the loads are turned on.

5. Verify that the engine speed is within the specification under each load condition.

- If load condition is not as specified, inspect the following:

- A/C switch and related wiring harness No.23 A/C Does Not Work Sufficiently No.24 A/C Is Always On Or A/C Compressor Runs Continuously
- Fan switch and related wiring harness Testing and Inspection

Idle speed (ATX: P, N position, MTX: Neutral position)
- 600-700 rpm (MTX), 650-750 (ATX)

Idle-up speed (ATX: P, N position, MTX: Neutral position)
- A/C on and refrigerant pressure sensor (middle pressure) is off: 700-800 rpm (MTX), 650-750 (ATX)
- A/C on and refrigerant pressure sensor (middle pressure) is on: 700-800 rpm (MTX), 670-770 (ATX)
- Electrical loads on: 650-800 rpm

Throttle position (TP) sweep inspection

1. Connect the M-MDS to the DLC-2.

2. Switch the ignition to ON.

3. Verify that none of the following DTC are displayed:

- P0122:00, P0123:00, P0222:00, P0223:00, P0638:00, P2100:00, P2101:00, P2107:00, P2108:00, P2119:00, P2122:00, P2123:00, P2127:00, P2128:00, P2135:00, P2138:00

- If any one DTC is displayed, perform DTC inspection. DTC Table [Engine]

4. Access TP_REL PID.

5. Verify that the PID reading is within the CTP_REL value. Component Tests and General Diagnostics

- If the PID reading is out of range, perform the following:

- Remove the air duct from the throttle body.
- Verify that the throttle valve opens when the accelerator pedal is depressed.

- If the throttle valve opens, inspect the TP sensor and related wiring harness.
- If the throttle valve does not open, inspect the throttle actuator control motor and related wiring harness.

6. Gradually depress the throttle pedal and verify that the PID reading increases accordingly.

- If the PID reading drops momentarily, inspect the following:

- TP sensor

7. Fully depress the throttle pedal and verify that the PID reading is within WOT value. Component Tests and General Diagnostics

- If the PID reading is out of range, perform the followings:

- Remove the air duct from throttle body.
- Verify that the throttle valve opens when throttle pedal is depressed.

- If the throttle valve opens, inspect the TP sensor and related wiring harness.
- If the throttle valve does not open, inspect the throttle actuator control motor and related wiring harness.

Variable Intake Air Control Operation Inspection

1. Start the engine.

2. Inspect the rod operation under the following condition: Rod operation





- If the rod operation is not as specified, inspect as follows:

a. Stop the engine.

b. Connect the M-MDS to the DLC-2.

c. Verify that DTC P0661:00 or P0662:00 is not displayed.

- If DTC P0661:00 or P0662:00 is shown, perform DTC inspection. P0661 P0662

d. Inspect the variable intake air solenoid valve. Variable Intake Air Solenoid Valve Inspection

- If the variable intake air solenoid valve is not normal, replace the variable intake air solenoid valve. Service and Repair
- If the variable intake air solenoid valve is normal, inspect the following:

- Vacuum hose and vacuum chamber for looseness or damage
- Shutter valve actuator Variable Intake Air Shutter Valve Actuator Inspection
- Shutter valve stuck open or closed

Continued in Part 2 Part 2
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