ALTERNATOR GP-CHARGING 4370125 - Caterpillar

System Operation Description:Use this procedure to troubleshoot the following diagnostic codes:
338-5 Engine Pre-Lube Pump Relay current below normal
338-6 Engine Pre-Lube Pump Relay current above normalThis procedure troubleshoots the output circuit for the prelube relay. Refer to Troubleshooting, "Prelubrication System" in order to troubleshoot the circuit for the prelubrication pressure switch.The prelubrication system is an option. If Caterpillar did not supply the prelube system, the prelube function is disabled. The following codes are also disabled:
E233 (3) Low Engine Pre-Lube Pressure
338-5 Engine Pre-Lube Pump Relay current below normal
338-6 Engine Pre-Lube Pump Relay current above normal
339-5 Engine Pre-Lube Pressure Switch current below normalThe prelube system is enabled when the "Engine Pre-Lube Time Out Period" is programmed for a time period that is between 30 and 300 seconds.If the "Engine Pre-Lube Time Out Period" is programmed for a time period of zero seconds, the prelubrication is disabled. The engine will crank without the prelubrication. The E233 (3) event code and the 338-5, 338-6, and 339-5 diagnostic codes are disabled.The prelube pump will not operate if the emergency stop button is activated or if the engine speed is greater than 0 rpm.During the prestart, the Electronic Control Module (ECM) can energize the prelube pump before cranking the engine. The pump provides lubrication to the engine bearings. When the conditions permit operation and the logic determines that lubrication is required, the ECM provides +Battery voltage to the prelube relay. The prelube relay provides pressurized air or gas to the prelube pump motor. The prelube pump motor rotates the prelube pump. After activation, the prelube system will operate until one of the following occurrences:
Closure of the prelubrication pressure switch
Completion of the "Engine Pre-lube Time Out Period"
Activation of the emergency stop buttonThe ECM monitors the prelubrication pressure switch in order to verify lubrication of the engine prior to start-up. The pressure switch is normally open. The pressure switch closes when the prelube pump raises the engine oil pressure to 9 3 kPa (1.3 0.4 psi). Closure of the pressure switch indicates that sufficient oil pressure has been achieved. After the pressure switch closes, the prelube pump continues to operate for a programmable time ("Engine Pre-Lube Time Out Period"). The engine starting sequence continues when the engine prelube sequence is complete.If the ECM does not detect closure of the pressure switch within the programmed time, the ECM monitors the engine oil pressure sensor. The pressure determines whether lubrication has occurred. If the prelubrication does not occur, an E233 (3) Low Engine Pre-Lube Pressure is generated. The starting sequence is terminated.The prelube pump can also be operated with a manual switch. When the switch is closed, a +Battery signal is sent to the ECM. The ECM provides +Battery voltage to the prelube relay until one of these conditions occur:
Closure of the prelubrication pressure switch
Activation of the manual prelube switch
Activation of the emergency stop buttonThe prelubrication system also operates after shutdown. The postlube ensures that the turbocharger has adequate lubrication during coast mode. When the engine reaches