TURBOCHARGER GP 1209188 - Caterpillar

Check for the Pressure Switch
Disconnect the 2 pole connector from the pressure switch.
Use a multimeter to measure the resistance between the two contacts. When there is no pressure in the system the resistance should be 22,000 Ohm. If necessary, remove the switch to make sure that no pressure is present below the pressure switch. You will only need to remove the upper part. The diverter valve can be left in place. When the adjusted pressure is reached, the contact should close.
Press the test button on the pump to start a test cycle.
When possible, mount a pressure gauge between the diverter valve and the pressure switch