RADIATOR GP 9Y7326 - Caterpillar

Illustration 1 g00738823
Schematic of the modulating valve for the auxiliary hydraulics (A1)Test Step 1. CHECK FOR A SHORT TO GROUND IN THE SOLENOID (A1)
Turn the key start switch to the OFF position.
Raise the cab. See Operation and Maintenance Manual, "Cab Tilting".
Disconnect the connector for the modulating valve (A1).
Measure the resistance from each of the coil wires to the machine frame.Expected Result:The resistance should be greater than 5000 Ohms.Results:
OK - The resistance is greater than 5000 Ohms. Proceed to Test Step 2.
NOT OK - The resistance is less than 5000 Ohms.Repair: The solenoid coil has failed. Replace the coil. Stop.Test Step 2. CHECK FOR A SHORTED WINDING IN THE SOLENOID (A1)
Measure the resistance of the coil.Expected Result:The resistance should be approximately 2.5 Ohms.Results:
OK - The resistance is approximately 2.5 Ohms. Proceed to Test Step 3.
NOT OK - The resistance is less than 1.5 Ohms.Repair: The solenoid coil has failed. Replace the coil. Stop.Test Step 3. CHECK FOR A SHORT IN THE WIRE HARNESS
Reconnect the connector for the modulating valve (A1).
Remove the floorplate in order to get to the ECM.
Disconnect the wire harness from the ECM.
Measure the resistance from contact 40 (wire P978-GN) to contact 42 (wire L998-OR) of the wire harness connector.Expected Result:The resistance should be approximately 3 Ohms.Results:
OK - The resistance is approximately 3 Ohms. Proceed to Test Step 4.
NOT OK - The resistance is less than 1.5 Ohms.Repair: The circuit is shorted in the wire harness. Locate the shorted wires. Repair the wire harness or replace the wire harness. Stop.Test Step 4. CHECK FOR A SHORT TO GROUND IN THE WIRE HARNESS
Measure the resistance from contact 40 (wire P978-GN) and contact 42 (wire L998-OR) of the wire harness to the machine frame.Expected Result:The resistances should be greater than 5000 Ohms.Results:
OK - The resistances are greater than 5000 Ohms.Repair: The ECM is very unlikely to have failed. Reconnect all connections and visually inspect the wire harness. Verify that the values that are present on the machine configuration screen match the machine's options. Verify that the values that are present on the machine configuration screen are installed correctly. Verify that the diagnostic code still exists. If the diagnostic code still exists perform the test steps again.Replace the ECM, if the cause of the diagnostic code was not found after the second attempt. See Testing and Adjusting, "Electronic Control Module (ECM) - Replace". Stop.
NOT OK - The resistance is less than 5000 Ohms on one of the readings.Repair: The circuit is shorted in the wire harness. Locate the shorted wires. Repair the wire harness or replace the wire harness. Stop.