UNIT TROUBLESHOOTING PROCEDURES
EXTENDED SERVICE PROGRAM (ESP)
TRUCK, CARGO, 2-1/2-TON, 6X6, M44A3 SERIES TRUCKS (DIESEL)
a. This work package provides the information needed to diagnose and correct malfunctions of the CTIS.
CTIS is used primarily with the vehicle compressed air system. If a particular malfunction is not covered, refer
to Mechanical Troubleshooting (WP 0009 00), and locate the troubleshooting procedure for the malfunction
observed. To obtain the maximum number of observed symptoms of the malfunction, question the operator.
b. Listed are CTIS malfunctions that may occur in the vehicle. The CTIS air system schematic found in
WP 0386 00 is to be used as a reference when performing CTIS troubleshooting procedures. To find a
specific malfunction, refer to the symptom index (WP 0018 00).
TEST OR INSPECTION
CTIS WILL NOT INFLATE OR DEFLATE
Eyeshields must be worn when releasing compressed air.
Failure to do this may result in injury to personnel.
Do not disconnect air lines before draining air reservoirs.
Small parts under pressure may shoot out with high velocity,
causing injury to personnel.
If tire pressure falls below 10 psi (69 kPa), CTIS will not
Step 1. If ECU is not operating, see malfunction 6.
Step 2. Check compressed air system (WP 0013 00).
If compressed air system falls below 75 psi (517 kPa), the
priority pressure switch will shut off air supply to CTIS.
Test 1. Perform electrical inspection/continuity check.
Step 1. Disconnect large pin 10 plug from ECU.
Step 2. Turn ignition ON.
Step 3. Using multimeter, measure the voltage from pin 9 to chassis ground. With ignition ON,
the reading should be 10-15 volts. If voltage is not present, perform steps 6-12.
Step 4. Turn ignition OFF. Pin 9 voltage should drop to zero volts.
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