BODY 8J0771 - Caterpillar

Table 2
FMI 3 Troubleshooting
1. Check the Harness For an Open
A. Turn key start switch and disconnect switch OFF.
B. Disconnect the switch from the machine harness.
C. Disconnect the J1 and J2 machine harness connectors at the ECM.
D. At the machine harness connector for the switch, place a jumper between the two signal wires at the switch connector. Check for low resistance at the ECM connector
E. At the machine harness connector for the ECM, measure the resistance between the signal contact and frame ground.
The resistance is less than 5 KΩ. OK - The circuit is correct.
Proceed to Test Step 2.
NOT OK - The resistance is greater than 5K Ω. The circuit is open.
Repair: Repair or replace the machine harness.
Note: A resistance that is greater than 5 Ω but less than 5K Ω indicates a loose connection or a corroded connection in the circuit. A resistance measurement that is greater than 5K Ω indicates an open in the circuit.
Proceed to Test Step 6.
2. Check the Harness for a Short
A. The key switch remains OFF.
B. All harness connectors remain disconnected.
C. Remove the jumper wire installed in the previous step.
D. At the machine harness connector for the ECM, measure resistance between the signal contacts and all other contacts of the J1 and J2 harness connectors.
The resistances are greater than 5K Ω. OK - The resistance is greater than 5K Ω. The harness circuit is correct.
Proceed to Test Step 34.
NOT OK- The resistance less than 5 Ω.
Repair: A short exists in the harness between the signal circuit and the wire with the low-resistance reading. Repair or replace the machine harness.
Note: A resistance that is greater than 5 Ω but less than 5K Ω would indicate a loose connection or a corroded connection in the circuit. A resistance measurement that is greater than 5K Ω would indicate an open in the circuit.
Proceed to Test Step 6.
3. Check the Ground Source for the Switch.
A. The key switch remains OFF.
B. All harness connectors remain disconnected.
C. At the switch, measure resistance between the ground contact and frame ground.
The resistance is less than 5 Ω. OK - The resistance is less than 5 Ω.
Proceed to Test Step 4.
NOT OK - The resistance is greater than 5K Ω.
Repair: The switch does not have a good ground source. Replace the harness between the switch and the ground source.
Note: A resistance that is greater than 5 Ω but less than 5K Ω indicates a loose connection or a corroded connection in the circuit. A resistance measurement that is greater than 5K Ω indicates an open in the circuit.
Proceed to Test Step 6.
4. Check the Operation of the ECM.
A. The key switch remains OFF.
B. Reconnect all harness connections.
C. Using a wire removal tool, remove the signal wires and socket from the machine harness connector to the switch.
D. Turn the key switch ON.
E. Use a multimeter probe to contact both signal wire pins through the empty space in the harness connector.
F. Ground the other end of the multimeter probe to frame ground.
G. Observe the