VALVE GP-RELIEF 2258026 - Caterpillar

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Terminal locations at the P1 ECM connector for the analog sensors
(P1-3) Sensor return
(P1-16) Auxiliary temperature (if equipped)
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Terminals at the customer connector that are associated with the auxiliary temperature sensor
(11) Auxiliary temperature (if equipped)
(15) Sensor return
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Terminal locations at the sensor connector for the analog sensors
(Terminal 1) Sensor signal
(Terminal 2) Sensor return
The connection of any electrical equipment and the disconnection of any electrical equipment may cause an explosion hazard which may result in injury or death. Do not connect any electrical equipment or disconnect any electrical equipment in an explosive atmosphere.
Test Step 1. Check for "Active" or "Logged" Diagnostic Codes
Connect Caterpillar Electronic Technician (ET) to the service tool connector.
Restore power to the ECM.
Monitor the diagnostic codes on Cat ET. Check and record any diagnostic codes. Note: Wait at least 30 seconds in order for the diagnostic codes to become active.
Determine if the problem is active and related to one of the following diagnostic codes:
-3 Voltage above normal
-4 Voltage below normalExpected Result:No diagnostic codes are active at this time.Results:
OK - No diagnostic codes are active at this time.Repair: There may be an intermittent electrical problem. If an intermittent electrical problem is suspected, refer to Troubleshooting, "Electrical Connectors - Inspect" for information that is related to troubleshooting intermittent electrical problems.STOP
Not OK - An active -3 diagnostic code is present. Proceed to Test Step 2.
Not OK - An active -4 diagnostic code is present. Proceed to Test Step 4.Test Step 2. Check for a Short Circuit to the +Battery at the Sensor Connector
Measure the voltage on the harness side of the sensor connector between pin 1 and pin 2 for the suspect sensor(s). Expected Result:The supply voltage is less than battery voltage.Results:
OK - The supply voltage is less than battery voltage. Proceed to Test Step 3.
Not OK - The supply voltage is equal to battery voltage.Repair: There is a short in the harness to the +Battery. Repair the harness wiring, when possible. If necessary, replace the harness.STOPTest Step 3. Create a Short Circuit at the Sensor Connector
Disconnect the suspect sensor.
Fabricate a jumper wire that is long enough to create a short circuit at the connector for the suspect sensor. Crimp connector pins to each end of the jumper wire.
Disconnect the connector from the suspect sensor.
Use the wire jumper in order to create a short between terminal 1 (sensor signal) and terminal 2 (analog return) at the sensor connector.
Restore power to the ECM.
Access the "Active Diagnostic Code" screen on Cat ET. Check for an active -4 diagnostic code for the suspect sensor. Note: Wait at least 30 seconds in order for the diagnostic codes to become active.
Remove power from the ECM. Expected Result:A -4 diagnostic code is now active for the suspect sensor(s).Results:
OK - A -3 diagnostic code was active before creating the short at the sensor connector. A -4 diagnostic code became active after creating the short at the sensor connector.Repair: Temporarily connect a new sensor to the harness, but do not install the new sensor in the engine. Verify