TM-9-2350-311-20-1

HOWITZER, MEDIUM, SELF-PROPELLED, 155MM; M109A2, M109A3, M109A4 AND M109A5

TECHNICAL MANUAL; UNIT MAINTENANCE MANUAL FOR HULL, POWERPLANT, DRIVE CONTROLS, TRACKS, SUSPENSION, AND ASSOCIATED COMPONENTS

AUGUST 1994

TM-9-2350-311-20-1 - Page 415 of 1275

TM9-2350-311-20-1

CONTINUED FROM STEP A

B

1. Reconnect bulkhead-to-coolant heater

control box wiring harness to coolant heater.

2. Disconnect battery ground leads.

3. Disconnect lead 400 from heater control

box.

4. Place red lead of multimeter in lead 400 and

black lead to ground.

5. Reconnect battery ground leads.

6. Turn MASTER switch ON and check for

voltage.

7. Turn MASTER switch OFF.

Is voltage present?

Troubleshoot master relay circuit

(para 3-3b).

C

1. Reconnect lead 400 to heater control box.

2. Disconnect battery ground leads.

3. Disconnect bulkhead-to-coolant heater

control box wiring harness from heater

control box.

4. Place red lead of multimeter on pin C (lead

430C) and black lead to ground.

5. Reconnect battery ground leads.

6. Turn MASTER switch ON, heater

control switch to start, and check for voltage.

7. Turn MASTER and heater control switches

OFF.

Is voltage present?

I

Replace heater control box (para

14-9).

CONTINUED ON NEXT PAGE

3-315