System Inspection

Fuel Injector Operation
Using an oscilloscope and SST-(Engine Signal Monitor)
1. Remove the ECM.
2. Connect the SSTs to the ECM.
3. Warm up the engine to normal operating temperature and let it idle.
4. With no electrical load operating, check the fuel injector control signal at the ECM terminals 4U, 4V, 4W, 4X, 4Y and 4Z by using an oscilloscope.




5. Increase the engine speed and verify that the signal changes.
6. If signal cannot be detected, or shows no change, check voltage at following terminals.
- ECM terminal 3B (Mass air flow sensor)
- ECM terminal 4H, 4E (Crankshaft position sensor)

Using the SST-New Generation Star (NGS)




1. Connect the SST to the data link connector-2.
2. Warm up the engine to normal operating temperature and let it idle.
3. Select the PID/DATA MONITOR AND RECORD function of the NGS.
4. With no electrical load operating, select "INJ RH" and "INJ LH" on the NGS display. NGS measures and shows the fuel injector pulse widths.
5. Increase the engine speed and verify that the pulse width changes.
6. If signal cannot be detected, or shows no change, check voltage at following terminals.
- ECM terminal 3B (Mass air flow sensor)
- ECM terminal 4H 4E (Crankshaft position sensor).

Fuel Cut Operation
Without using SST-New Generation Star (NGS)
1. Warm up the engine to normal operating temperature and let it idle.
2. Turn off the A/C switch.
3. Connect a tachometer to the data link connector terminal IG-.
4. Open the throttle valve and increase the engine speed to 4,000 rpm. Check each fuel injector operation by using a sound scope or screwdriver.




5. Close the throttle valve quickly. Verify that no fuel injector operating sound is heard while decreasing engine speed to approx. 1,200 rpm.
6. If not as specified, check voltage at following terminals.
- ECM terminal 3G (Engine coolant temperature sensor)
- ECM terminal 3L (Closed throttle position switch)
- ECM terminal 4E, 4H (Crankshaft position sensor)

Using SST-(NGS)




1. Connect the SST to the data link connector.
2. Warm up the engine to normal operating temperature and let it idle.
3. Turn off the A/C switch.




4. Select the PID/DATA MONITOR AND RECORD function of the NGS.
5. Select "INJ RH" and "INJ LH" on the NGS display. NGS measures and shows the fuel injector pulse width.
6. Open the throttle valve and increase the engine speed to 4,000 rpm.
7. Close the throttle valve quickly. Verify that the fuel injector pulse width becomes Ohms until the engine speed drops to approx. 1,200 rpm, then recovers after that.
8. If not as specified, check voltage at following terminal
- ECM terminal 3G (Engine coolant temperature sensor)
- ECM terminal 3L (Closed throttle position switch)
- ECM terminal 4E, 4H (Crankshaft position sensor)




Dechoke Operation
1. Turn the ignition switch to START and verify that the engine start or ignition occur while cranking.
2. Depress the accelerator pedal wide open throttle and turn the ignition switch to START Verify that no injector operating sound is heard while cranking by using a sound scope or screwdriver.
3. If not as specified, check the ECM terminal 3F voltage. (Throttle position sensor)