PISTON AS 5I8632 - Caterpillar

System Operation Description:Use this procedure to troubleshoot the electrical system if a problem is suspected with the prelubrication system or if one of the diagnostic codes in Table 1 is active or easily repeated.
Table 1
Diagnostic Codes Table
Description Conditions which Generate this Code System Response
338-5 Engine Pre-Lube Pump Relay current below normal The engine's Electronic Control Module (ECM) detects an open circuit at the prelube pump relay.
The ECM detects a short to battery voltage at the prelube pump relay.
The ECM can only detect this condition when the prelube pump relay is not energized. The code is logged.
338-6 Engine Pre-Lube Pump Relay current above normal The ECM detects a short circuit at the prelube pump relay.
The ECM can only detect this condition when the prelube pump relay is energized. The ECM has the ability to automatically prelube the engine before cranking. This prelubrication may increase the life of certain engine parts. The ECM will prelube the engine, when the Engine Control Switch (ECS) is placed in the START position. The ECM will prelube the engine, when the ECS is placed in the AUTO position and the remote start/run/stop switch is closed. The length of time for the prelube cycle can be programmed by the customer. The prelube cycle will end when the pressure switch for the prelube system closes or if the customer programmed time ends. The engine speed must equal zero rpm before the prelube will begin.The prelube cycle has the following status codes."OFF" - The ECM is powered and the ECS is in the STOP position."ON" - The ECM is powered and the ECS is in the START position."COMPLETED" - The prelube has timed out or the prelubrication pressure switch has activated."DISABLED" - The engine prelube duration is programmed to 0.The prelube function will be aborted when one of the following conditions occur:
The pressure switch for the prelube system is activated.
The user defined engine prelube duration has been reached.
The operator activates the prelube override switch.When the ECM senses the ECS in the START position, the ECM will activate the output driver for the "PPR1" relay. When the "PPR1" relay energizes, the normally open contacts of the "PPR1" relay close. This allows current to flow to the prelube motor. The prelube motor activates the prelube pump. The prelube pump builds pressure in the engine's lubrication system. When the pressure switch for the prelube system closes as a result of the increased pressure, the ECM input for the pressure switch is taken low. The ECM then knows that the pressure in the system is adequate. The ECM will begin the starting sequence.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 g01241988
Typical schematic
Illustration 2 g01241989
P1 ECM connector
(P1-5) Digital return
(P1-66) Prelube override switch
Illustration 3 g01241990
P2 ECM connector
(P2-12) Driver output for Prelube
(P2-66) Digital return
Illustration 4 g01241992
Customer connector
(Terminal i) Prelube override switch
(Terminal y) PPR2 contacts
(Terminal z)