Inspection Procedure 5
CIRCUIT OPERATION- The battery positive voltage is applied on the ignition coil by the ignition switch-IG.
- When the PCM turns the power transistor in the PCM "OFF," battery positive voltage is applied on the ignition power transistor (terminals 3), and the ignition power transistor turns "on."
- When the ignition power transistor turns on, the ignition coil's primary circuit is grounded by the ignition power transistor terminal 4. Then the primary current flows to the ignition coil.
COMMENT
- In cases such as the above, the cause is probably no spark, fuel delivery, or fuel quality problems.
In addition, foreign materials (water, kerosene, etc.) may be mixed with the fuel.
TROUBLESHOOTING HINTS
The most likely causes for this case:
- Malfunction of the ignition system.
- Malfunction of the fuel pump system.
- Malfunction of the injector system.
- Malfunction of the PCM.
- Foreign materials in fuel.
WIRING DIAGRAM
CONNECTORS
DIAGNOSIS
Required Special Tools:
MB991502: Scan Tool (MUT-II)
MB991348: Test Harness
STEP 1. Check the battery voltage.
1. Measure the battery voltage during cranking.
- The voltage should be 8 volts or more. If the voltage is 8 volts or more, go to Step 2.
If the voltage is less than 8 volts, check the battery. Refer to Battery. Then confirm that the malfunction symptom is eliminated.
STEP 2. Check the timing belt for breaks.
If the timing belt is not broken, go to Step 3.
If the timing belt is broken, replace the timing belt. Then confirm that the malfunction symptom is eliminated.
CAUTION: To prevent damage to the scan tool, turn the ignition switch "OFF" before connecting or disconnecting the scan tool.
STEP 3. Using scan tool MB991502, check data list and actuator test.
1. Check the following items in the data list.
Data List Reference Table & Normal Scan Data Values
a. Item 16: Power Supply Voltage.
b. Item 22: Crankshaft Position Sensor.
c. Item 21: Engine Coolant Temperature Sensor.
2. Check the following items in the actuator test.
Actuator Test Reference Table
a. Item 07: Fuel Pump.
If the checks above meet the specifications, go to Step 4. If the checks above do not meet the specifications, repair or replace. Then confirm that the malfunction symptom is eliminated.
STEP 4. Check the ignition system.
1. Connect the tachometer to inspection connector A-16X terminal 3.
2. Crank the engine.
- The tachometer should indicate cranking speed.
If the cranking speed is normal, go to Step 5. If the cranking speed is not normal, refer to INSPECTION PROCEDURE 32 - Ignition Circuit System.
STEP 5. Check the ignition timing.
1. Check the ignition timing at cranking.
Standard value: 5° BTDC ± 3°
If within specifications, go to Step 6.
If not within specifications, check that the crankshaft position sensor and timing belt cover are in the correct position. Then confirm that the malfunction symptom is eliminated.
STEP 6. Check the circuits at the PCM connector C-39.
1. Disconnect the PCM connector C-39 and measure at the harness side.
2. Disconnect the PCM connector C-40. Using a jumper wire, connect terminal 49 to ground and activate the MFI relay.
3. Turn the ignition switch "ON."
4. Connect the terminals 1, 2, 9, 10, 24 and 25 to ground via a 20 Ohm resistor. Measure the current at this time. The PCM terminals correspond to the injectors as follows.
a. PCM terminal 1 when measuring number 1 cylinder injector.
b. PCM terminal 9 when measuring number 2 cylinder injector.
c. PCM terminal 24 when measuring number 3 cylinder injector.
d. PCM terminal 2 when measuring number 4 cylinder injector.
e. PCM terminal 10 when measuring number 5 cylinder injector.
f. PCM terminal 25 when measuring number 6 cylinder injector.
- The current should be 0.3 ampere or more.
5. Turn the ignition switch "OFF."
If not within specifications, go to Step 7.
If within specifications, check the PCM connector C-39, and repair or replace as required. Refer to Harness Connector Inspection >. If the PCM connector C-39 is in good condition, go to Step 10.
STEP 7. Check the power supply line at the injector connectors B-17, B-19, B-21, B-22, B-25, B-30.
1. Disconnect the connectors B-17, B-19, B-21, B-22, B-25, B-30 and measure at the harness side.
2. Turn the ignition switch "ON."
3. Connect the terminal 1 to the ground via a 20-Ohm resistor. Measure the current at this time.
- The current should be 0.5 ampere or more.
4. Turn the ignition switch "OFF."
If within specifications, go to Step 8.
If not within specifications, check the intermediate connector B-26, and repair or replace as required. Refer to Harness Connector Inspection >. If the intermediate connector B-26 is in good condition, repair the harness wires between the PCM connector C-39 and the injector connectors B-17, B-19, B-21, B-22, B-25, B-30. Then check that the malfunction is eliminated.
STEP 8. Check the injector.
1. Disconnect the injector connector.
2. Measure resistance between each injector side connector terminals 1 and 2.
Standard value: 13 - 16 Ohm [at 20 ° C (68° F)]
If within specifications, go to Step 9.
If not within specifications, replace the injector. Then check the malfunction is eliminated.
STEP 9. Check the harness connectors B-17, B-19, B-21, B-22, B-25, B-30 at the injector for damage.
If the harness connectors B-17, B-19, B-21, B-22, B-25, B-30 are damaged, repair or replace them. Refer to Harness Connector Inspection >.
If the harness connectors B-17, B-19, B-21, B-22, B-25, B-30 are in good condition, check the intermediate connector B-26, and repair or replace as required. Refer to Harness Connector Inspection >. If the intermediate connector B-26 is in good condition, repair the harness wires between the PCM connector C-39 and the injector connectors B-17, B-19, B-21, B-22, B-25, B-30.
Then check that the malfunction is eliminated.
STEP 10. Check the following items.
1. Check the following items, and repair or replace the defective items.
a. Check the ignition coil, spark plugs, spark plug cables.
b. Check if the injectors are clogged.
c. Check if the foreign materials (water, kerosene, etc.) got into fuel.
d. Check compression.
Then confirm that the malfunction symptom is eliminated.