CAP 4B8247 - Caterpillar

Illustration 2 g03651255
Schematic of the Analog Passive circuits
Table 3
Temperature Sensor Output Resistance (Ohms)
-25 °C (-13 °F) 13052.6
-20 °C (-4 °F) 9716.7
-15 °C (5 °F) 7302.3
-10 °C (14 °F) 5538.0
-5 °C (23 °F) 4236.7
0 °C (32 °F) 3268.3
5 °C (41 °F) 2541.5
10 °C (50 °F) 1991.4
15 °C (59 °F) 1571.9
20 °C (68 °F) 1249.5
25 °C (77 °F) 1000.0
30 °C (86 °F) 805.5
35 °C (95 °F) 652.8
40 °C (104 °F) 532.3 Note: The diagram above is a simplified schematic of the connections for the sensor signal (analog passive) circuits. The schematic is electrically correct. However, not all of the possible harness connectors are shown. Refer to the latest revision of the Electrical Schematic, UENR3832 for the complete schematic.Diagnostic Trouble Code Procedure
Note: Prior to beginning this procedure, inspect the harness connectors that are involved in this circuit. Poor connections can often be the cause of a problem in an electrical circuit. Verify that all connections in the circuit are clean, secure, and in good condition. If a problem with a connection is found, correct the problem and verify that the diagnostic code is active before performing a troubleshooting procedure. For sensors powered via the fuse panel, check the condition of the appropriate fuse before beginning the troubleshooting procedure.
Table 4
Troubleshooting Test Steps Values Results
1. Identify The Active DTC Code Associated With The Suspect Circuit
Code present. FMI 3 diagnostic code, proceed to Test Step 2.
FMI 4 diagnostic code, proceed to Test Step 5.
Begin Process For FMI 3 Troubleshooting HERE
2. Check The Sensor
Note: See Table 3 for a list of resistances related to specific temperature values. The maximum resistance for the sensor is 33,650 Ω, the minimum is 21.9 Ω.
A. Turn the key start switch and the disconnect switch to the OFF position.
B. Disconnect the sensor from the harness.
C. Measure the resistance between pin 1 and 2 of the sensor.
The resistance reading agrees with the values from Table 3. OK - The resistance reading agrees with the values in 3.
Proceed to Test Step 3.
NOT OK - The resistance reading does not agree with the values in 3.
Repair: Replace the sensor.
Proceed to Test Step 7.
3. Check For An Open In The Sensor Circuit
A. The key start switch and disconnect switch remain in the OFF position.
B. The harness connector remains disconnected from the sensor.
C. Disconnect the J1 and J2 connectors from the ECM.
D. At the harness connector for the sensor install a jumper wire.
E. At the harness connector for the ECM measure the resistance at the contacts for the sensor.
The resistance reading 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 5 Ω.
Repair: Either the signal or the return circuit wire is open. Repair or replace the harness.
Proceed to Test Step 7.
4. Check The Signal Circuit For A Short.
A. The disconnect switch and the key start switch remain in the OFF position.
B. The harness connectors J1 and J2 remain disconnected from the ECM.
C. Remove the jumper wire that was installed during