ROD 0976596 - Caterpillar

Illustration 1 g03845478
Table 2
CID: 2661
Position Resistance
All the Way Cold 1K Ω
All the Way Hot 10 -11K Ω Note: The diagram above is simplified schematic of the Machine ECM connections. The schematic is electrically correct. However, not all of the possible harness connectors are shown. Refer to the latest revision of Electrical Schematic , UENR0072 for the complete schematic.
Table 3
Troubleshooting Test Steps Values Results
1. Identify Active DTC Code Associated With Sensor Circuit
Code present
FMI 3 diagnostic code, proceed to Test Step 2.
FMI 4 diagnostic code, proceed to Test Step 8.
Begin Process For FMI 3 Troubleshooting HERE
2. Check The Supply Voltage at the Sensor
A. Turn key start switch and disconnect switch ON.
B. Disconnect the machine harness from sensor.
C. Measure voltage between supply and return contacts at the machine harness connector for the sensor.
Voltage is 24V 0.5
OK - The voltage reading is correct for the suspected faulty sensor.
Proceed to Test Step 5.
STOP
NOT OK- The voltage is NOT correct for the circuit.
Proceed to test step 3.
3. Check The Ground Source at the Sensor
A. Turn key start switch and disconnect switch OFF.
B. Measure resistance between the return contact and frame ground.
The resistance is less than 5 Ω.
OK - The resistance is less than 5 Ω.
Proceed to test step 4.
STOP
NOT OK- Resistance is greater than 5K Ω.
Repair - The ground has failed. repair/repace the wiring harness for the ground.
4. Reset the Circuit Breaker.
A. Turn key start switch and disconnect switch OFF.
B. Connect all harness connectors.
C. Reset the circuit breaker for the circuit.
D. Observe the status of the diagnostic code.
The FMI 3 goes from active to logged.
OK - The FMI 3 goes from active to logged. Resume normal machine operation.
STOP
NOT OK- The diagnostic code remains.
Repair - The wiring harness for the power supply has failed. Repair or replace the wring harness.
STOP
5. Check For An Open In The Sensor Circuit
A. The sensor remains disconnected from the machine harness.
B. Turn the key start switch and the disconnect switch OFF.
C. At the harness connector for the sensor, place a jumper wire between the signal contact and frame ground.
D. Disconnect J1 and J2 harness connectors from the ECM.
E. At machine harness connector for ECM, measure the resistance from the signal contact for the sensor to frame ground.
F. Gently pull on the wire and move the wire in a circular motion at ECM connector and observe the resistance readings. Repeat the process for the sensor connector.
The resistance is less than 5 Ω at all times during the manipulation of the harness.
OK - The resistance is less than 5 Ω. The signal circuit and the ground circuits of the sensor are not open in the machine harness.
Proceed to Test Step64.
NOT OK - Resistance reading for the signal circuit or the return circuit is greater than 5 Ω.
Repair: Check the signal circuit or the ground circuit for opens or bad connections.
Note: A resistance that is greater than 5 Ω but less than