TM 9-6115-729-24
0013
ELECTRONIC TECHNICIAN (ET) TROUBLESHOOTING - Continued
MALFUNCTION
168-02 code. Electrical system voltage intermittent/erratic.
168-03 code. Electrical system voltage above normal.
168-04 code. Electrical system voltage below normal.
CORRECTIVE ACTION
STEP 1.
On EMCP set ENGINE CONTROL switch to OFF/RESET. Set Battery
Disconnect Switch to OFF. Set DEAD CRANK SWITCH to OFF.
STEP 2.
Check the battery voltage.
a. Measure the open circuit voltage at the battery terminals.
b. Load test the batteries (WP 0049). Use the 4C-4911 battery load tester or
equivalent.
(1) If the no-load voltage at the batteries is at least 24 1 Vdc, and the
batteries pass the load test. Proceed to STEP 3.
(2) If the battery voltage is incorrect and/or the battery fails the load test, the
batteries or the alternator are causing the problem. Recharge the
batteries or replace the batteries (WP 0049). Verify that the original
condition is resolved.
STEP 3.
Check the voltage to the ECM.
a. Remove ECM connector ENG-P1.
b. Set Battery Disconnect Switch to ON. Set DEAD CRANK SWITCH to
NORMAL. On EMCP set ENGINE CONTROL switch to COOL
DOWN/STOP.
c.
Measure the voltage between ENG-P1-48 and ENG-P1-61.
d. Measure the voltage between ENG-P1-52 and ENG-P1-63.
e. Measure the voltage between ENG-P1-53 and ENG-P1-65.
f.
Measure the voltage between ENG-P1-70 and ENG-P1-65.
g. On EMCP set ENGINE CONTROL switch to OFF/RESET. Set Battery
Disconnect Switch to OFF. Set DEAD CRANK SWITCH to OFF.
h. Reconnect ECM connector ENG-P1.
(1) If the voltage measured at steps 3c., 3d., 3e., and 3f. is 24 3 Vdc. The
ECM is receiving the correct voltage.
(2) On the ECM inputs from the ENGINE CONTROL switch, if the voltage is
not 24 3 Vdc. Proceed to STEP 4.
(3) If the voltage is not 24 3 Vdc at the +battery terminals on ECM
connector P1, proceed to STEP 5.
STEP 4.
Check the voltage inputs to ENGINE CONTROL switch and to ECM.
a. Set Battery Disconnect Switch to ON. Set DEAD CRANK SWITCH to
NORMAL. On EMCP set ENGINE CONTROL switch to COOL
DOWN/STOP.
0013-14
