FAN GP 4647092 - Caterpillar

Table 2
Troubleshooting Test Steps Values Results
1. Check for Codes
A. Connect Cat® Electronic Technician (ET) to the service tool connector.
B. Determine if a code is active or logged.
Codes
Result: A -3 code is active or logged.
Proceed to Test Step 2.
Result: A -4 code is active or logged.
Proceed to Test Step 3.
Result: A -8 code is active or logged.
Proceed to Test Step 5.
2. Create a Short at the Sensor Connector
A. Turn the keyswitch to the OFF position.
B. Disconnect the sensor with the active -3 code.
C. Install the jumper wire between the following terminals at the sensor connector:
- Pin 2 (sensor return) and Pin 3 (sensor signal)
D. Connect Cat ET.
E. Use Cat ET to monitor the following:
- -4 code
F. Turn the keyswitch to the OFF position.
Create a Short
Result: A -4 code became active.
Repair: The wiring harness is OK. Replace the sensor.
Verify that the repair eliminated the problem.
Result: A -4 code did not become active.
Proceed to Test Step 4.
3. Create an Open at the Sensor Connector
A. Turn the keyswitch to the OFF position.
B. Disconnect the sensor with the active -4 code.
C. Connect Cat ET.
D. Use Cat ET to monitor the following:
- -3 code
E. Turn the keyswitch to the OFF position.
Create an Open
Result: A -3 code became active.
Repair: The wiring harness is OK. Replace the sensor.
Verify that the repair eliminated the problem.
Result: A -3 code did not become active.
Proceed to Test Step 4.
4. Check the 8 VDC Supply Voltage at the Sensor Connector
A. Turn the keyswitch to the ON position.
B. Measure the voltage at the following pin locations of the affected sensor connector:
- Pin 1 and Pin 2
C. Reconnect the sensor.
Supply Voltage
Result: The supply voltage is approximately 8.0 0.2 VDC
Proceed to Test Step 8.
Result: The supply voltage is not approximately 8.0 0.2 VDC.
Repair: There is a short in the wiring harness to the battery. Repair or replace the wiring harness.
If the problem is not resolved, proceed to Test Step 5.
5. Check the PWM Circuit for an Open
A. Turn the keyswitch to the OFF position.
B. Disconnect the sensor with the active -8 code.
C. Disconnect the J2 connector at the Electronic Control Module (ECM).
D. Measure the resistance between the following locations for the sensor:
- Pin 3 (sensor connector) and the appropriate PWM signal wire on the ECM connector
Open Circuit
Result: There were less than 10 ohms of resistance between the sensor connector and the ECM connector.
Proceed to Test Step 6.
Result: There were more than 10 ohms of resistance between the sensor connector and the ECM connector.
There is an open circuit in the wiring harness. Repair or replace the wiring harness.
If the problem is not resolved, proceed to Test Step 6.
6. Check the PWM Circuit for a Short Circuit
A. Turn the keyswitch to the OFF position
B. Disconnect the sensor with the active -8 code.
C. Disconnect the J2 connector at the ECM.
D. Measure the resistance between the following locations for the sensor:
- Pin 3 (sensor connector) and Engine ground
Short Circuit
Result: There were more than 100 K ohms of resistance between pin 3 and engine ground.
Proceed to Test Step