PLUG 6W7379 - Caterpillar

All Generator Set Engines Equipped With Electronic Modular Control Panels (EMCP)Reference: Service Manuals: SR 4 Electronic Modular Control Panel, SENR3535; and SR 4 Control Panel (9Y1400), SENR3903.This article includes information about the following subjects:
- Unwanted engine shutdown caused by "01" diagnostic (no magnetic speed sensor signal) and additional troubleshooting information currently not available from the References.- Unwanted engine shutdown caused by "04" diagnostic (loss of set points programmed into the ECM memory).- Release of new "09" diagnostic (failed pressure transducer in the new 9X8203 Control Group, and the new 7X6182 Sensor Module) and related troubleshooting procedure.Unwanted Engine Shutdown Caused By "01" Diagnostic
There have been reports of unwanted generator set shutdowns with a "01" diagnostic display on the Engine Control Module (ECM). According to the Service Manual, a "01" diagnostic display indicates that there is no signal to the ECM from the magnetic speed sensor.
There are two methods the ECM determines a lack of speed signal input. The first method is by leaking a very small amount of current through the sensor to detect continuity. Step 1, of problem 1 in the EMCP Service Manuals, outlines the method to troubleshoot the sensor for continuity problems. This is a valid and useful step which can be used to determine the integrity of the sensor wiring.
Step 2 relates to the lack of a signal incoming to the ECM due to problems other than lack of continuity. The diagnosis of the problem in this step assumes that the fault lies in either the speed sensor, the ECM, or an incorrect air gap setting on the sensor. In fact, there are a number of problems which can cause a "01" diagnostic, and the present troubleshooting procedure can lead a service person to replace an ECM that is not faulty.
The following is the second method by which a "01" diagnostic is declared. After the ECM determines that continuity is present and after the starter motor relay in the ECM is energized to start the generator set, the ECM begins looking for a frequency signal from the magnetic pickup. If no signal is present, then the ECM declares a "01" diagnostic. The generator set is shutdown and cannot be started until the "01" diagnostic is cleared and the air shutoff (if provided) is reset. The fallacy in this diagnostic process is that the ECM assumes that no problems exist in the starting system, when in reality, any number of problems could exist in the starting system which would result in a "01" diagnostic. A list of known problems which can cause the "01" diagnostic follows:
1. Failed starter motor or starter motor pinion solenoid.2. Failed circuit breaker (CB2).3. Failed starter motor mag switch (SMMS1 or SMMS2).4. Butt engagement of the starter pinion with the flywheel ring gear.5. Blown fuse on the ECM starter motor relay output.6. Faulty wiring anywhere in the starting system components. In addition, for generator sets with and optional prelube pump:
7. Failed prelube pump.8. Failed prelube pump mag switch.9. Failed prelube pump