Usage:
STEP 1. Check For Intermittent Or Permanent Fault Condition
Test Procedure:
Momentarily de-energize the power to the locomotive governor J1 pins 8 and 9. Perform the normal procedures for starting the engine and note the LED status on the main governor box while the engine is cranking.
Expected Results:
Shutdown LED should stay on during cranking and engine should not start.
STEP 2. Check Speed Sensor Signal
Test Procedure:
Disconnect the engine wiring harness from the speed sensor and the J2 connector on the locomotive governor. Reconnect the speed sensor to the J2 connector on the locomotive governor with the following "T" harness.
Use a DMM (Caterpillar service tool 6V3030) on the 20 volt DC scale and monitor the voltage at monitoring point C with respect to point B.
Expected Results:
5 ± 2 volt DC during cranking.
0 or 10 ± 1 volts DC not cranking
STEP 3. Check Supply to Speed Sensor
Test Procedure:
Retain the "T" harness connected as in step 2.
Use a DMM (Caterpillar service tool 6V3030) on the 20 volt DC scale and monitor the voltage at monitoring point A with respect to point B.
Expected Results:
10 ± 1 volts DC during cranking.
10 ± 1 volts DC not cranking.
STEP 4. Check Speed Sensor Supply From The Governor Box
Test Procedure:
Disconnect the "T" harness from the speed sensor. Keep it plugged into the J2 connector on the governor box.
Use a DMM (Caterpillar service tool 6V3030) on the 20 volt DC scale and monitor the voltage at monitoring point A with respect to point B.
Expected Results:
10 ± 1 volts DC during cranking.
10 ± 1 volts DC not cranking.
STEP 5. Check Shutdown Lamp
Test Procedure:
Retain the "T" harness connected in step 2. Perform the normal procedures for starting the engine and note the LED status on the main governor box while the engine is cranking.
NOTE: The engine cannot start with this "T" harness connected in place of the regular engine/locomotive harness.
Expected Results:
Shutdown LED should go off during cranking.
Step 6. Check Engine Harness
Test Procedure:
Check the electrical continuity of the engine/locomotive harness between the following pins.
J2 connector pin 6 to speed sensor connector pin C
J2 connector pin 7 to speed sensor connector pin A
J2 connector pin 8 to speed sensor connector pin B
Also check for any electrical short circuits between the engine/locomotive chassis and the above three harness connections.
Repair harness faults and STOP.
STEP 7. Intermittent Fault
Test Procedure:
With an intermittent fault it is not always possible to conclusively identify the cause. The three possible causes, in order of probability, are:
Wiring Harness
Speed sensor
Governor box
First check the electrical continuity of the engine/locomotive harness between the following pins.
J2 connector pin 6 to speed sensor connector pin C
J2 connector pin 7 to speed sensor connector pin A
J2 connector pin 8 to speed sensor connector pin B
Also check for any electrical short circuits between the engine/locomotive chassis and the above three harness connections.
Perform these checks while "jiggling" the wires in the immediate proximity of any connections such as terminal strips, speed sensor connector etc. that are in the electrical path. Also check for any corroded connections.
Repair any harness faults and if its connector is corroded, replace the speed sensor according to Service Procedure C. and STOP.
Next check, and if necessary reset, the speed sensor air gap according to Service Procedure C. If the air gap was too small, inspect the sensor for evidence of contact with the flywheel ring gear. If evidence indicates contact, replace the speed sensor according to Service Procedure C. and STOP.
If the above procedures check out OK, the problem could be in the governor box; it is more likely to have been a marginal harness connection tha has now been fixed by being disturbed.
Put the locomotive in service; if this same intermittent problem repeats itself, and the above procedures again check out OK, replace the governor box.