MOTOR GP-ELEC 0R4272 - Caterpillar

Use this procedure to troubleshoot the electrical system if a problem is suspected with a prelubrication system. Also, use this procedure if one of the diagnostic codes in Table 1 is active or easily repeated.
Table 1
CDL Code and Description Conditions which Generate the Code System Response
338-5 Engine Pre-Lube Pump Relay : Current Below Normal The Electronic Control Module (ECM) detects an open in the circuit for the prelubrication relay.
The ECM detects a short to battery voltage in the circuit for the prelubrication relay. The code is logged.
338-6 Engine Pre-Lube Pump Relay : Current Above Normal The ECM detects a short in the circuit for the prelubrication relay. The ECM can lubricate the engine before cranking begins. This engine prelubrication is used to increase the life of certain engine parts by lubricating these parts before the starting motor is engaged.There are several configuration parameters that define the operation of the prelubrication system. Prior to troubleshooting problems that are associated with the prelubrication system, check the settings of these parameters. Be sure that you understand the proper operation of the system.The charge pressure status of the prelubrication system may be communicated to several different controllers that are on the application. Depending on the status that is communicated there could be an effect on the engine starting. The following status indicators are communicated over the data link:
"Prelube OFF" or "Prelube disabled"
"Prelube waiting for oil"
"Prelube waiting to fill"
"Perlube ready to start"
"Prelube failed"
"Prelube ready to start"
"Continuous prelube"Some of these status indicators report the parameter settings of the prelubrication system. The ECM determines the charge pressure status via the engine oil pressure sensor.The prelubrication system is activated at ECM powerup. The ECM prevents the starting motor from engaging while the pump builds pressure in the lubrication system.Also, a manual prelube switch may be wired to P1-60 terminal at the primary ECM connector. When this ECM input is grounded, the ECM will activate the prelubrication relay. Refer to Troubleshooting, "Switch Circuits - Test" for information related to troubleshooting this switch circuit.An override for the prelubrication system is available in Caterpillar Electronic Technician (ET). The override allows the technician to activate the prelubrication system for service and testing. The test is functional only when the engine speed is zero rpm. The test is accessed by selecting the following menus on Cat ET:
"Diagnostics"
"Diagnostic Tests"
"Override Parameters"
Illustration 1 g02784357
Schematic for the prelubrication system if equipped with an A4 ECM
Illustration 2 g06320888
Schematic for the prelubrication system if equipped with an A5 ECM
Illustration 3 g03676535
Location of the prelubrication pump and the prelubrication solenoid (engine view)
(1) Prelubrication pump
(2) Prelube solenoid
Illustration 4 g02579136
Location of the ECM connectors (front side engine view)
(3) ECM
(4) J2/P2 ECM connector
(5) J1/P1 ECM connector
(6) Connector for the left rail
Table 2
Troubleshooting Test Steps Values Results
1. Inspect the Electrical Connectors and the Wiring
A. Remove the electrical power from the ECM.
B. Thoroughly inspect connectors (4), (5), and (6). Also, thoroughly inspect the other connectors for the prelubrication relay that are in the circuit. Refer to Troubleshooting, "Electrical Connectors - Inspect" for the proper procedure for inspecting