Ignition Timing: Adjustments

*** UPDATED BY TSB # 1085791 Oct. 85

1. With the engine running at normal operating temperature, check the idle speed. If the idle speed is not between 800 and 900 RPM, adjust it to 850 RPM.
2. Check the adjustment of the throttle switch.
3. Check the timing and if necessary, adjust to 14° BTDC. If the ignition timing deviates by more than 7°, stop the engine.
4. Restart the engine, allow to idle, and recheck the ignition timing. If the timing still deviates more than 7°, check the ignition system as outlined below.

Fig. 85 Test Connector:

The ignition system incorporates a self diagnostic function. This function can be used for testing the system by connecting a tester to the test connector of the system. The connector is located forward of the electrical distribution box.
1. Connect the ignition system tester to the test connector, Fig. 85. Ensure the ignition is in the off position.
2. Turn on the ignition and start the engine. Check that the green LED (fault indication) lights for about 2 seconds during the starting process.
3. Run the engine until it reaches normal operating temperature. During warm-up, the engine must not exceed 2,300 RPM.
4. Allow the engine to idle and check the operation of the LEDs. If these are flashing, read the number of flashes and use the table below to determine the fault.
NOTE: The flashing of the green LED can also be read on the "Check Engine" lamp. The red LED is only located on the tester, and it is for knocking.

NUMBER OF FLASHES
GREEN RED FAULT CORRECTIVE ACTION

1 NOT USED

2 NOT USED

3 NOT USED

4 1. Knocking sensor with cable 1. Disconnect the shielded cable from both the ECU and knock sensor and measure the resistance between pins 12 and 13 of the ECU connector (always make connections at the cable end of the connector). If there is continuity between the pins, replace the cable.
2. If no continuity is found, jump the pins at the oxygen sensor end of the cable (always make connections at the cable end of the connector) and remeasure the continuity of pins 12 and 13 of the ECU connector. If the circuit is open, replace the cable. If the circuit is complete, replace the knock sensor.

2. Faulty ECU Replace the ECU.

5 Faulty LH system input signal Check the blue/red cable between connector 24 of the fuel system ECU and connector pin 8 of the ignition system ECU for continuity (always make connections at the cable end of the connector). If the cable is in good condition, replace the fuel system ECU.

Sporadic Indicates knocking Normal operation

Continuous Maximum timing retard Check for abnormal engine vibration such as loose plates, brackets, etc. Repair vibrations as needed.