CORE AS-AFTCLR 1752277 - Caterpillar

The engine oil pressure signal also connects to the EMS circuit. If the signal is failed, a problem with the operation of the EMS also exists.Engine Oil Pressure Switch Check
The engine oil pressure switch functions as follows: engine stopped - switch is open, engine running - switch is closed. If faulty operation of the engine oil pressure switch is suspected, perform the following check. The engine oil pressure switch also connects to the EMS circuit. If the switch is failed, a problem with the operation of the EMS also exists. Procedure1. Disconnect the wires from the engine oil pressure switch. Stop the engine. Check for continuity across the switch terminals. Allow enough time for the oil pressure to bleed down after stopping the engine. The correct result is NO continuity.* There is continuity; the switch is failed. Replace the engine oil pressure switch.* There is NO continuity; go to STEP 2.2. Start the engine. Check for continuity across the switch terminals. The correct result is continuity.* There is continuity; the switch is good.* There is NO continuity; the switch is failed. Replace the engine oil pressure switch. For a more precise test, bench test the engine oil pressure switch.The engine oil pressure switch specifications are: Actuation pressure ... 93.0 20.8 kPa (14.0 3.0 psi)Deactuation pressure ... 68.9 20.8 kPa (10.0 3.0 psi)Switch normally open below ... 68.9 20.8 kPa (10.0 3.0 psi)System Test
Engine Overspeed Control
(1) Diagnostic Lamp #1. (2) Diagnostic Lamp #2. (3) Diagnostic Lamp #3. (4) Diagnostic Lamp #4. (5) Connector plug A. (6) Connector receptacle B. The system test only applies to the 9X-4407 and 112-7459 Engine Overspeed Control Assemblies. This includes all D11N's, 994's, 793's and some other OHT's. The Engine Overspeed Control Assembly part number is located on the back of the control (side opposite the diagnostic lamps). The warning indicators and the engine speed pickup must function correctly before performing this test. See Warning Indicator Test and Problem 2 - Engine Speed Signal.This test determines if the engine overspeed control is operating correctly. Perform the test only if there is an unexplained system failure. Installation of the system test harness places the engine overspeed control in the system test mode. This decreases (to a normal operating range) the defined RPM values at which the warning indicators are activated. Correct operation of the engine overspeed control is verified by increasing and decreasing the RPM in the normal operating range. For correct operation, see the System Test Mode Operation chart. The main purpose of