SWITCH AS-PRESSURE 2526677 - Caterpillar

System Operation Description:During normal operation, coolant is sent to the air intake system in order to cool the intake air. A jacket water aftercooler in the air lines after the turbochargers cools the air before the air enters the air-to-air aftercooler. When the vehicle is at idle in cold climates, the aftercooler may overcool the engine. The engine coolant diverter valve stops the flow of coolant to the aftercooler in order to prevent the system from overcooling the engine. The system also allows the vehicle's cab heater to maintain a sufficient capacity during cold ambient conditions."Coolant Diverter Valve Test"The "Coolant Diverter Valve Test" is available to help diagnose problems with the engine coolant diverter solenoid. A small current is applied to the circuit at all times. This allows the Engine Control Module (ECM) to detect open circuits when the valve is not actuated. A short circuit will only be detected when the valve is actuated.The following conditions must be met before the "Coolant Diverter Valve Test" will function:
Engine speed is 0.
Vehicle speed is 0.
The neutral switch is in the Neutral position.
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Schematic for the engine coolant diverter solenoidTest Step 1. Inspect the Electrical Connectors and the Wiring
Turn the keyswitch to the OFF position.
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Location of the J2/P2 ECM connector
Thoroughly inspect the J2/P2 ECM connector and the solenoid connector. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
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Terminal locations at the P2 ECM connector for the engine coolant diverter solenoid (P2-8) Engine coolant diverter solenoid (P2-53) Return
Perform a 45 N (10 lb) pull test on each of the wires in the ECM connector and the solenoid connector.
Check the allen head screw for each of the ECM connectors for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
Check the harness and wiring for abrasion and for pinch points.Expected Result:All connectors, pins, and sockets are completely coupled and/or inserted and the harness and the wiring are free of corrosion, of abrasion, or of pinch points.Results:
OK - The electrical connectors and wiring are OK. Proceed to Test Step 2.
Not OK - There is a problem with the electrical connectors and/or the wiring.Repair: Repair the connectors or wiring and/or replace the connectors or wiring. Ensure that all of the seals are properly in place and ensure that the connectors are completely coupled.Verify that the repair eliminates the problem.STOPTest Step 2. Determine the Condition that is Present
Connect Caterpillar Electronic Technician (ET) to the data link connector.
Turn the keyswitch to the ON position.
Check for active diagnostic codes that are related to the engine coolant diverter solenoid.
Start the "Coolant Diverter Valve Test" in the "Special Tests" under the "Diagnostics" menu on Cat ET.
Once Cat ET displays the status of the engine coolant diverter solenoid, stop the "Coolant Diverter Valve Test".Expected Result:The