AIR/FUEL RATIO CONTROL AND IGNITION SYSTEM Caterpillar

Ignition System Checks

1: Check for spark.

a. Check spark plugs to see if operating properly.

Expected Result: Spark plugs are operating properly.

Result:

* Spark plugs are operating properly.

Proceed to next step.

* Spark plugs are not operating properly.

Proceed to STEP 5.

2: Check ignition timing

a. Check ignition timing.

Expected Result: Engine timing is correct.

Result:

* Engine timing is not correct.

Proceed to next step.

* Engine timing is correct.

Proceed to STEP 9.

3: Check the ignition system's magnetic pickup.

(1) 6V7070 Multimeter. (2) DIS magnetic pickup. (3) Magnet.

a. Connect 12 VDC to the magnetic pickup and the 6V7070 Multimeter.

b. Place the N-pole end of the magnet next to the magnetic pickup as shown in the illustration.

NOTE: Re-install in threaded hole in the digital ignition system shield. The pickup is to be backed out 3/4 turn from disc surface.

Expected Results: Multimeter measures a low resistance for the magnetic pickup.

Result:

* Multimeter measures a low resistance for the magnetic pickup.

Proceed to next step.

* Multimeter does not measures a low resistance for the magnetic pickup.

Adjust and/or replace magnetic pickup. STOP.

4: Check wiring.

a. check for loose connections, etc.

Expected Result: No continuity.

Result:

* No continuity.

Check connections. Repair or replace wiring if necessary. STOP.

* Continuity.

Replace ignition module. STOP.

5: Check spark plug and ignition leads.

a. Check for loose connections, etc.

Expected Result: Loose connection.

Result:

* Loose connections.

Secure connections. STOP.

* Firmly connected.

Proceed to next step.

6: Check supply voltage of ignition system.

a. check voltage.

Expected Result: No voltage.

Result:

* No voltage.

Check connections. Repair or replace wiring. STOP.

* Voltage present.

Proceed to next step.

7: Check DIS 10 pin connector.

a. Check resistance of the Digital Ignition System (DIS) connector with the 6V7070 Multimeter. Refer to the chart for the proper leads.

Expected Result: Resistance is above 250000 Ohms

Result:

* Resistance is above 250000 Ohms.

Proceed to next step.

* Resistance is not above 250000 Ohms.

Replace ignition module. STOP.

8: Check DIS 6 pin connector.

a. Check resistance of the Digital Ignition System (DIS) connector with the 6V7070 Multimeter.

Measure the resistance between pin E and pin F.

Expected Result: Resistance is above 1000 Ohms.

Result(s):

Resistance is above 1000 Ohms.

Proceed to next step.

Resistance is not above 1000 Ohms.

Replace ignition module.

9: Check throttle valve.

a. Turn key ON, engine OFF.

b. Check for movement during the self calibration mode of the governor.

Expected Result: No movement.

Result(s):

* No movement of the throttle valve.

Refer to the Governor Troubleshooting Guide. STOP.

* Movement of the throttle valve.

Refer to check the engine. STOP.