TM-9-2320-272-24-1

TRUCK, 5-TON, 6X6, M939, M939A1, AND M939A2 SERIES TRUCKS (DIESEL)

TECHNICAL MANUAL; UNIT, DIRECT SUPPORT, AND GENERAL SUPPORT MAINTENANCE MANUAL; VOLUME 1 OF 4

JUNE 1998

TM-9-2320-272-24-1 - Page 228 of 1015

TM 9-2320-272-24-1

Table 2-3. Electrical Troubleshooting (Contd).

MALFUNCTION

TEST OR INSPECTION

CORRECTIVE ACTION

25. SYSTEM OPERATES INCORRECTLY IN ONE OR MORE POSITIONS OF DIRECTIONAL SIGNAL CONTROL LEVER

Test directional signal control unit continuity.

Step 1.

Place battery switch to OFF position.

Step 2.

Remove harness connector from control unit.

NOTE

Remove indicator lamp before making tests.

Step 3.

Remove indicator lamp from directional signal control (para. 3-113).

Step 4.

Set multimeter to RX1 for continuity reading.

Step 5.

Set control lever in each of four operating positions and test.

If any lead does not test as shown in tables below, replace directional signal control unit

(para. 3-113).

A. DIRECTIONAL SIGNAL CONTROL LEVER

IN NEUTRAL POSITION

C. DIRECTIONAL SIGNAL CONTROL LEVER

IN RIGHT TURN POSITION

FROM PIN

TO PIN

CONTINUITY

FROM PIN

TO PIN

CONTINUITY

INDICATED

INDICATED

H

A

Open

F

G

Shorted

H

B

H

H

C

Open

A

Shorted

Open

H

E

H

E

Shorted

B

C

Open

H

D

Shorted

H

E

C

Open

D

G

F

Shorted

D

Open

C

Shorted

Open

D

E

Open

B. DIRECTIONAL SIGNAL CONTROL LEVER

IN LEFT TURN POSITION

D. DIRECTIONAL SIGNAL CONTROL LEVER

IN HAZARD WARNING POSITION

FROM PIN

TO PIN

CONTINUITY

FROM PIN

TO PIN

CONTINUITY

INDICATED

INDICATED

H

B

H

H

B

H

C

Shorted

H

A

Shorted

Shorted

A

Open

H

Shorted

C

Shorted

H

E

Open

H

E

Shorted

F

G

Shorted

D

E

D

E

C

D

C

Shorted

Open

D

Open

Open

F

G

Shorted

END OF TESTING!

2-140