TM 10-3930-675-24-1
ELECTRONIC CONTROL UNIT (ECU) INPUT VOLTAGE TROUBLESHOOTING - CONTINUED
0013 00
Table 1. Error Code 121 - Supply Voltage to Servo ECU (790) Failure
Troubleshooting Procedures - Continued.
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
Error Code 121 - Supply Voltage to Servo ECU
b. If no voltage (24V) is found at
(790) Failure - Continued.
X154 pin 1, check circuit
breaker F30 and continuity of
wires A1501 and 301 (WP
0048 00-32).
c. Replace damaged or faulty
circuit breaker (WP 0074 00).
d. Repair or replace damaged
wires or connectors (WP 0013
00).
e. Replace damaged or faulty
emergency stop switch (WP
0082 00).
3. Disconnect
ECU
(790) a. If no voltage (24V) is found,
connector 1 and check voltage
check continuity of wires
(24V) at pins 1 and 15 with the
A1544A and A1544B (WP
ignition ON (WP 0048 00-5).
0048 00-5).
Inspect ECU (790) connector 1 b. Repair or replace damaged
pins and connector for
wires or connectors (WP 0113
damage.
00).
c. Replace damaged ECU (790)
(WP 0080 00).
0013 00-2
