TM-9-2320-386-24-1-1
2-1/2-TON, 6X6, M44A3 SERIES TRUCKS (DIESEL)
TECHNICAL MANUAL; EXTENDED SERVICE PROGRAM (ESP); UNIT, DIRECT SUPPORT AND GENERAL SUPPORT; MAINTENANCE MANUAL; VOLUME 1 OF 2
MAY 2001
TM-9-2320-386-24-1-1 - Page 86 of 1078
TM 9-2320-386-24-1-1
0012 00
0012 00-18
Electrical Troubleshooting (Contd)
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
Step 1. Check harness connector for continuity and voltage.
a. Separate instrument cluster from instrument panel (WP 0094 00).
b. Disconnect harness connector from tachometer.
NOTE
Place accessory/battery switch in ON position when checking pin A
to pin D, and pin B to pin C. Switch is in OFF position when
checking pin C to pin D, and pin D to ground.
c. Using multimeter, test harness connector as shown in chart below. Replace
tachometer if harness connector passes test (WP 0095 00).
d. If reading from pin B to pin C is not within limits, perform step 2.
Step 2. Check if magnetic sensor is defective.
a. Check that 2-pin connector is intact with front wiring harness.
b. Reset gap of magnetic sensor.
c. Loosen jamnut and turn magnetic sensor clockwise to bottom-out on flywheel.
d. Turn magnetic sensor 1 to 1-1/2 turns counterclockwise and tighten jamnut against
flywheel housing.
e. Retest pin B to pin C. If reading is not within limits, replace magnetic speed sensor
(WP 0097 00).
END OF TESTING!
Tachometer Harness Connector Test
TEST POINT
READING
Pin A to pin D
28 Vdc
Pin B to pin C
0.5-5 Vdc; 0.2 Vdc max.
Pin C to pin D
0 ohms
Pin D to ground
0 ohms
FLYWHEEL HOUSING
MAGNETIC SENSOR
(FROM BATTERY SW) 28 VDC
SHIELDING
27
A
A
B
C
D
E
F
B
C
D
E
F
429
428
99
770C
40
FRONT HARNESS
TACHOMETER
GROUND TERMINAL ON INSTRUMENT PANEL
FLANGE
OUTPUT TO STE/ICE
LAMP FEED
2 PIN
CONNECTOR
429
428
99
WIRING DIAGRAM OF TACHOMETER CIRCUIT
Back to Top
