TM 5-3805-281-24-1
Sub-System Diagnostics
START AID RELAY (K12)
1--24 Volt Terminal
YES: Relay is OK. Check
CHECK
2--Ground Terminal
switch and harness.
3--Relay Common
4--Relay Normally Closed
NO: Relay has failed.
5--Relay Normally Open
Replace.
Disconnect harness from start aid relay.
Connect ohmmeter to terminals 3 and 5.
T7447BG
1914JAN91
Does ohmmeter read open?
Connect 24 volts to relay terminal 1 and ground terminal
2.
Does relay "click"?
Connect ohmmeter to terminals 3 and 5.
9015
Does ohmmeter read continuity?
15
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NOTE: A diode can fail in two modes, either shorted or open. Continuity will be
START AID COIL
YES: If continuity is
measured in one direction only in a serviceable diode. Use "diode checking mode" on
SUPPRESSION DIODE
measured in both checks,
meter when checking continuity.
(V1) CHECK
diode has failed in a
shorted mode. Replace.
NO: If continuity is NOT
measured in either check,
diode has failed in an
open mode. Replace.
NO: If continuity is
measured in one check
and not the other, diode
T118385 UN21NOV98
is OK.
Remove diode from connector.
Connect an ohmmeter to diode terminals.
Is continuity measured?
Reverse ohmmeter probes.
Is continuity measured?
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