HOSE AS 4839942 - Caterpillar

Table 5
Troubleshooting Test Steps    Values    Results    
5. Check for Battery Voltage on the Signal Wire
A. Measure the voltage between the terminals for the sensor signal and the analog return on the harness connector for the suspect sensor.
   
Voltage    
Result: The voltage measurement is less than the +Battery voltage.
The signal wire is not shorted to the +Battery. Proceed to Test Step 6.
Result: The voltage measurement is equal to the +Battery voltage.
The signal wire is shorted to the +Battery.
Repair the wiring, when possible. Replace parts, if necessary. Verify that the problem is resolved.
   
6. Check the Signal Wire for an Open Circuit
A. Disconnect the sensor that is applicable to the diagnostic code.
B. Connect a jumper wire between the signal terminal and the return terminal on the harness connector for the suspect sensor. The jumper wire will replace the sensor with a short circuit.
C. Check that the -3 diagnostic code becomes a -4 diagnostic code with the jumper wire in place.
   
Diagnostic code    
Result: The -3 code does not change to a -4 code when the jumper wire is connected.
Connect the sensor. There is a problem with the wiring harness or with the ECM. Proceed to Test Step 7.
Result: The -3 code changes to a -4 code when the jumper wire is connected. The wiring harness and the ECM are OK.
Perform the following procedure:
1. Remove the jumper wire.
2. Connect a new sensor to the engine harness. Do not install the sensor into the engine.
3. Verify that the active -3 diagnostic code does not recur.
4. Install the sensor into the engine.
5. Clear all logged diagnostic codes and return the engine to service.
   
Table 6
Troubleshooting Test Steps    Values    Results    
7. Check the ECM for Proper Operation
A. Fabricate a jumper wire that is long enough to create a test circuit across the ECM connector. Crimp connector sockets to each end of the jumper wire.
B. Determine the terminal location at the appropriate ECM connector for the signal wire and the return wire of the suspect sensor.
C. Remove the signal terminal and the return terminal from the ECM connector.
D. Install the jumper wire between the terminal locations for the signal and the return at the ECM connector. The jumper wire will effectively replace the engine wiring with a short circuit.
E. Use Cat ET to check for a -4 diagnostic code.
   
-4 code    
Result: A -4 code is active when the jumper wire is installed.
The ECM detected the jumper wire at the ECM connector. However, the ECM did not detect the jumper wire at the harness connector for the sensor. There is an open circuit in the wiring harness.
Repair the wiring harness, when possible. Replace parts, if necessary. Verify that the problem is resolved.
Result: A -4 code is not active when the jumper wire is installed.
There is a problem with the ECM. Temporarily install a new ECM. Refer to Troubleshooting, "ECM - Replace".
If the problem is resolved with the new ECM, install the original ECM and verify that