HARNESS AS-CONTROL 4741526 - Caterpillar

The supply voltage is routed to terminal 1 of each sensor connector. The sensor return is routed to terminal 2 of each sensor connector. The sensor signal is routed to terminal 3 of each sensor connector. The ECM provides short circuit protection for the internal power supply. A short circuit to the battery will not damage the internal power supply.Diagnostics on the Caterpillar Electronic Technician (ET)Wiggle Test - The Wiggle Test allows you to monitor the status of the signals from the sensors.For additional information regarding the Wiggle Test, refer to the documentation that accompanies the Cat ET software.
Illustration 1 g03724563Locations of the sensors and the sensor connectorsProbable Causes
Codes
Sensors
Wiggle test
LinesRecommended Actions
Table 2
Troubleshooting Test Steps Values Results
1. Check for Codes
A. Establish communication between Cat® Electronic Technician (ET) and the ECM .
B. Turn the keyswitch to the ON position.
C. Look for a -3, or -4 active or logged codes:
Diagnostic code
Result: A -3 diagnostic code is active.
Proceed to Test Step 2.
Result: A -4 diagnostic code is active.
Proceed to Test Step 3.
2. Create a Short at the Sensor Connector
A. Use a jumper wire in order to create a short between terminal 3 (signal) and terminal 2 (sensor return) at the sensor connector.
B. Turn the keyswitch to the ON position.
C. Monitor the diagnostic codes on Cat ET. Check for an active -4 diagnostic code for the suspect sensor.
D. Turn the keyswitch to the OFF position.
Short created
Result: A -4 diagnostic code became active after creating the short at the sensor connector.
The wiring is OK.
Repair: Replace the sensor.
Verify that the repair eliminated the problem.
Result: A -4 diagnostic code does not become active for the suspect sensor.
If the problem is not resolved, proceed to Test Step 4.
3. Create an Open at the Suspect Sensor Connector
A. Turn the keyswitch to the OFF position.
B. Disconnect the sensor connector of the suspect sensor with the active -4 diagnostic code.
C. Turn the keyswitch to the ON position.
D. Monitor the diagnostic codes on Cat ET. Check for an active -3 diagnostic code for the suspect sensor.
E. Turn the keyswitch to the OFF position.
Create an Open
Result: A -3 diagnostic code became active after disconnecting the sensor.
The wiring is OK.
Repair: Replace the sensor.
Verify that the repair eliminated the problem.
Result: A -3 diagnostic code did not became active after disconnecting the sensor.
If the problem is not resolved, proceed to Test Step 4.
4. Check the 5 VDC Supply Voltage at the Sensor Connector
A. Turn the keyswitch to the ON position.
B. Measure the voltage between pin 1 and pin 2 at the suspect sensor.
Test passed
Result: The supply voltage is approximately 5.0 0.2 VDC
Connect the sensor.
Proceed to Test Step 5
Result: The supply voltage is not approximately 5.0 0.2 VDC.
There is a short in the harness to the battery.
Repair: Repair the wiring or replace the harness
Verify that the problem is resolved.
STOP
5. Perform the Wiggle Test
Carefully following this procedure is the best way to identify the root cause of an intermittent problem.
A. Turn the keyswitch to the ON position.
B. Use CAT ET to run the "Wiggle Test".
C. Slowly