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Home >> Mazda >> 2011 >> 6 V6-3.7L >> Repair and Diagnosis >> Powertrain Management >> Computers and Control Systems >> Testing and Inspection >> Component Tests and General Diagnostics >> Engine Control System Operation Inspection >> Part 1

Part 1




ENGINE CONTROL SYSTEM OPERATION INSPECTION [MZI 3.7 V6]

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 GND to the GND 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.

Variable resistance type (TP sensor)





Input signal system inspection for variable resistance 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 for the following points concerning the PCM connector:

- Female terminal opening is 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 for the following points concerning the sensor connector:

- Female terminal opening is loose.
- Coupler (pin holder) damage
- Pin discoloration (blackness)

- If there are no problems, proceed to next investigation below.

Standard power supply system inspection for variable resistance type

- Confirm that the #3 terminal is at 5 V.

- If the measured voltage on the #3 terminal is 5 V, inspect the following points on the sensor connector.
- If there is no problem, inspect for the following:

- Female terminal opening is loose.
- Coupler (pin holder) damage
- Pin discoloration (blackness)

- If the #3 terminal measures other than 5 V, inspect for the following:

- Open or short circuit in wiring harness
- Harness/pin crimp is loose or disconnected.

GND system inspection for variable resistance type

- Confirm that terminal sensor #5 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 or short circuit in wiring harness
- Female terminal opening is loose causing an open or short circuit in wiring harness.
- Coupler (pin holder) damage
- Pin discoloration (blackness)
- Harness/pin crimp is loose or disconnected.

Thermistor type (IAT sensor and CHT sensor)





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 battery and main relay terminal A
- Harness and connector between PCM terminal 1AZ and main relay terminal D

Drive-by-Wire Control System Inspection

Engine coolant temperature compensation inspection

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

2. Access the following PCM PIDs:

- ECT
- 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:

- CHT sensor and related wiring harness Testing and Inspection
- 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, P0507:00 is not displayed.

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

4. Access the PCM PID RPM.
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 Climate Control Unit Inspection - Manual Air Conditioner Climate Control Unit Inspection - Full-Auto Air Conditioner
- Fan switch and related wiring harness Climate Control Unit Inspection - Manual Air Conditioner Climate Control Unit Inspection - Full-Auto Air Conditioner

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, P2101:00, P2107:00, P2111:00, P2112:00, P2122:00, P2123:00, P2127:00, P2128:00, P2135:00, P2138:00

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

4. Access the PCM PIDs TP1, TP2.

5. Verify that the PID reading is within the CTP 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. Testing and Inspection
- If the throttle valve does not open, inspect the throttle valve actuator 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. Testing and Inspection
- If the throttle valve does not open, inspect the throttle valve actuator control motor and related wiring harness.

Fuel Injector Operation Inspection





Fuel Cut Control System Inspection

NOTE:
- This inspection has to perform after the Fuel Injector Operation Inspection.

If active command mode function of the M-MDS is used:

1. Warm up the engine and idle it.

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

3. Select the PCM PIDs RPM and FUELSYS.

4. Monitor the both PIDs while performing the following steps.
a. Depress the accelerator pedal and increase the RPM PID to 4,000 rpm.

b. Quickly release the accelerator pedal (brake pedal is not depressed) and verify that the FUELSYS PID is OL, and CL when the RPM PID drops below 1,200 rpm.

- If not as specified, inspect the following.

- CHT sensor and related harness Testing and Inspection

If active command mode function of the M-MDS is not used:

1. Warm up the engine and idle it.

2. Measure the fuel injector control signal wave profile using the oscilloscope while performing the following steps.
a. Depress the accelerator pedal and increase the engine speed to 4,000 rpm.

b. Quickly release the accelerator pedal (brake pedal is not depressed) and verify that the wave profile constant B+, and appears wave, when the engine speed drops below 2,200 rpm.

- If not as specified, inspect the following.

- CHT sensor and related harness Testing and Inspection

Fuel Pump Operation Inspection

1. Remove the fuel-filler cap.

2. Switch the ignition to ON.

3. Turn the fuel pump relay from off to on using the PCM PID FP and inspect if the fuel pump operation sound is heard.

- If no operation sounds is heard, go to the next step.

4. Measure the voltage at fuel pump unit terminal B (wiring harness-side).

Specification
- B+ (Ignition switch at on)

- If the voltage is as specified, inspect the following:

- Fuel pump continuity
- Fuel pump ground

- If not as specified, inspect the following:

- Fuel pump relay Relay Inspection
- Wiring harness connector (Battery positive terminal-Fuel pump relay-Fuel pump)
- Wiring harness between fuel pump relay and PCM terminal 1BI

Spark Test

1. Disconnect the fuel pump relay.

2. Verify that each ignition coil and connector is connected properly.

3. Inspect the ignition system in the following procedure.

WARNING:
- High voltage in the ignition system can cause strong electrical shock which can result in serious injury. Avoid direct contact to the vehicle body during the following spark test.









Purge Control System Inspection

If active command mode function of the M-MDS is used:

1. Start the engine.

2. Disconnect the vacuum hose between the purge solenoid valve and the charcoal canister.

3. Put the finger to the purge solenoid valve and verify that there is no vacuum applied when the engine is cold.

- If there is a vacuum, inspect the following:

- Wiring harness and connectors (Purge solenoid valve terminal B-PCM terminal 2H)
- Purge solenoid vale (stuck open) Testing and Inspection

4. Connect the M-MDS to the DLC-2 and verify that the DTC P0443:00 is shown.

- If the P0443:00 are displayed, perform the DTC inspection. P0443

5. Select the PCM PID EVAPCP.

6. Increase the duty value of the purge solenoid valve to 50 % and inspect if the operation sound of the valve is heard.

- If the operation sound is heard, inspect for the loose or damaged vacuum hose. (Intake manifold-Purge solenoid valve-Charcoal canister)
- If the operation sound is not heard, perform the purge solenoid valve inspection.
Testing and Inspection

7. Warm up the engine to normal operating temperature.

8. Monitor the EVAPCP PID using the M-MDS, and drive the vehicle approx. 2,000 rpm for 30 s or more.

- If the EVAPCP PID is 0 %, inspect the PCM PIDs MAF, APP1, APP2, TP REL and LOAD.

Continued in Part 2 Part 2
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