ELBOW 9X8403 - Caterpillar

System Operation Description:Use this procedure to troubleshoot any suspect problems with the prelubrication system.This procedure covers the following open circuit diagnostic codes and short circuit diagnostic codes:
338-05 Pre-Lube Relay open circuit
338-06 Pre-Lube Relay short to groundThe Electronic Control Module (ECM) has the ability to automatically lubricate the engine before cranking. This may increase the life of certain engine parts by lubricating the parts before the starting motor is engaged.The prelubrication system is activated when the engine control is placed in the RUN or in the AUTO mode. The system prevents the starting motor from engaging while the pump builds pressure in the engine oil system. After a short period of time, the starting motor is allowed to engage. The keyswitch must be left in the START mode for the duration of the prelube cycle in order to start the engine.A test on Caterpillar Electronic Technician (ET) allows the technician to activate the prelube system. The test is functional when the engine speed is 0 rpm. The test is accessed by selecting the following menus on Cat ET:
Diagnostics
Diagnostic Tests
Override Parameters
Illustration 1 g01190683
Schematic
Illustration 2 g01166619
P2 ECM connector
(P1-66) Prelube relay
(P1-35) Digital return
(P1-12) Prelube pump Test Step 1. Inspect Electrical Connectors and Wiring
Turn the battery