ARMY TM   5-6115-612-34 MARINE CORPS TM 6115-34/8 AIR FORCE TO   35C2-3-471-2 NAVY AG-320B0-MME-000 10-1. PURPOSE AND FUNCTION OF ENGINE AND GENERATOR CONTROLS AND INSTRUMENTS. (cont.) b.   Functional Theory of Operation. (cont) position. As the switch moves to the OPEN position, +24  Vdc  from  the  switch  are  briefly  placed  on  the contactor open line to the EECM. This voltage pulse resets the shapers and latch circuit so that the latch set output changes state. The state change deactivates the contactor relay drive, the contactor line switches status,  and  the  contactor  relay  deenergizes.  This prevents power from the generator set from passing to the  output  cable,  but  has  no  effect  on  generator  or engine operation. The READY TO LOAD lamp remains on to show that placing the CONTACTOR switch in the CLOSED position will again route power to the load. (9)   Manual   shutdown.   A   manual shutdown is initiated by the operator. To manually shut down  the  generator  set,  the  operator  places  the MASTER SWITCH in the OFF position. This removed 24 Vdc from the EECM, shutting down the generator set. 10-2.  ENGINE  ELECTRONIC  CONTROL  MOD- ULE (EECM). Maintenance of the EECM consists of testing and repair procedures. The test procedures are intended to be the first step in troubleshooting, and are to   be   used   before   proceeding   to   the   EECM troubleshooting  procedures. a. Test. The following procedures determine the   operating   condition   of   the   EECM.   They   are performed either to locate the source of a fault in a malfunctioning EECM or, after repair of a faulty EECM, to ensure that the fault has been corrected. In each step of this procedure where the operator is told to make a measurement or observe an indication, if the proper response  is  not  noted,  refer  to  the  troubleshooting procedures of table 2-4. After the fault is repaired, the test procedure should be repeated to ensure that the problem has been corrected and that no other fault exist. In this procedure, it is assumed that the EECM has been removed from the generator set and is in a repair   area   with   its   connectors   accessible.   All references to controls and indicators are to those on the test fixture front panel. (See table 23). (1)   EECM   continuity   check.   Set multimeter on high ohms (200K ohms scale) and check continuity of EECM circuitry as follows: Power Supply board  etc,;  Diodes  and  interconnecting  circuitry  as follows: From To Readings J6-N J6-M 10k ohms J6-M J6-N 1 megohm J6-N J6-R 1 megohm J6-R J6-N 1 megohm J6-N 35–P 1 ohm J6-N J5-E 1 ohm J6-N 35–H 1 ohm J6-N J5–B 1 ohm J6-N F5–T 1 ohm J6-N F5–J 1 ohm J6-N J4–E 1 ohm J6-N J4-G 2k ohms J6-N J5-K 1 megohm J6-N J5–L 2k ohms J6-N J5-M 10k  ohms J6-N J5-C 1 megohm J6-N J5–D 10k  ohms J6-N J5-N 5k ohms J6-N J5-A 5k ohms Repair or replace damaged wires and connections as necessary. (2) Preliminary test procedure (a) Fabricate an EECM test fixture. An illustration, parls list, and schematic are provided in table   2-3.   Table   10–1   lists   additional   equipment required for EECM testing. (b)   Connect test equipment provided in table 10-1 and EECM as shown in figure 10-1. NOTE The oscilloscope is required only for the Fuel Pump Control Test, test step (17). (c)  Turn  external  power  supply  on and adjust voltage to 24–28 Vdc. 10-8 Change 1