
MEP 660 - Trouble shooting Manual
Doc No.: IM – 51
Rev.2.0
Print: October 2008
213
PARAMETER
DESCRIPTION
FAULT CODE
1204
FAULT MESSAGE EXPR Stuck Closed. Run Auto/Manual Test
RESTRICTIONS
Cranking prohibited
ALARM BELL
--
RESET LEVEL
Low, Manual
If the fault condition is still present when cleared manually, the fault
will be generated again.
FAULT
RECOVERY
Automatic when the EXPR interlock found open.
PROBABLE
CAUSES
1. Defective EXPR relay
2. Defective wiring.
3. Defective digital output card MLSD16 in slot No. 14.
FAULT
ISOLATION
1. Shut down the engine. Switch ON MB1, MB2, MPCB, MFPB1, and
MFPB2 circuit breakers. Check the status of the EXPR relay.
2. If EXP Relay is in energized position, check the voltage across the
EXPR coil terminals.
A. If the voltage is zero but relay is in picked up position, the relay
is defective. Replace the relay.
B. If the voltage is more than 65V, MLSD16 in slot No. 14 is
defective. Replace the card and check up.
3. If EXP Relay is in de-energised position, check the status of the
Green LED 2 on the digital input card in slot 9.
A. If the green LED 2 is glowing, disconnect the wire EXPRFB from
the EXPR relay interlock. Check the status of the Green LED.
a) If the Green LED 2 is still glowing, the wire EXPRFB is
shorted with some positive wire in the bunch. Identify and
remove the short circuit.
b) If the Green LED 2 is OFF, then the EXPR interlock is bad.
Replace the EXPR relay.
4. Run self test for the EXP relay to ensure proper feed back signal
under ‘Auto test for relays’ in the ‘Test Mode’ menu available in
main menu.