TM 9-2320-272-24-1
Table 2-7. CTIS Troubleshooting (Contd).
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
Test 2. Check for operation of pneumatic controller.
Select a different mode and listen for clicking noise. If click is not heard, repair or
replace pneumatic controller (para. 3-454).
Test 3. Determine if pressure switch circuit is functional.
Step 1. Check connection of electrical lead on pressure switch on wet tank. Clean and tighten.
CAUTION
Turn battery switch to "OFF position before disconnecting or
connecting ECU wiring harness. Failure to do so may result in
damage to ECU.
Step 2. Disconnect CTIS wiring harness cannon at ECU. Disconnect electrical lead at pressure
transducer and check for continuity to ECU cannon. If harness is faulty, repair
connections (para. 3-131) or replace CTIS wiring harness (para. 3-470).
Step 3. Connect multimeter to pressure switch at pin locations A and B. Start engine
(TM 9-2320-272-10) and operate until air pressure gauge, located on instrument
cluster, indicates more than 120 psi. Shut off engine and drain secondary tank
(TM 9-2320-272-10) until air pressure gauge indicates less than 80 psi. Pressure switch
should open (no continuity). If pressure switch remains closed (continuity) with
secondary tank less than 80 psi, replace pressure switch (para. 3-467).
Step 4. With engine running, drain secondary air tank (TM 9-2320-272-10) until air pressure
gage indicates less than 80 psi. If gauge does not reach 120 psi or greater, adjust air
governor (para. 3-207).
Step 5. Connect CTIS wiring harness cannon to ECU. With battery and CTIS switches in "ON"
position, check voltage from ECU to pressure switch. If voltage is less than 23 volts,
replace ECU (para. 3-468).
Step 6. Connect CTIS wiring harness electrical lead to pressure switch.
Test 4. Determine if pressure transducer circuit is functional.
Step 1. Check connection of electrical lead on pressure transducer, located on pneumatic
controller. Clean and tighten.
CAUTION
Turn battery switch to "OFF" position before disconnecting or
connecting ECU wiring harness. Failure to do so may result in
damage to ECU.
Step 2.
Disconnect CTIS wiring harness cannon at ECU. Disconnect electrical lead at pressure
gage and check for continuity to ECU cannon. If harness is faulty, repair connections
(para. 8-131) or replace CTIS wiring harness (para. 3-470).
Step 8.
Check voltage to ECU from vehicle's electrical supply.
Refer to malfunction 1, test 5, step 2.
Step 4.
Disconnect CTIS wiring harness electrical lead from pressure transducer.
Step 5.
Check voltage from ECU to pressure transducer. Voltage should be 4.75-5.25 volts.
If voltage is within limits, replace pressure transducer (para. 3-453).
Step 6.
If voltage from ECU to pressure transducer is outside 4.75-5.25 volts, and voltage from
vehicle's electrical supply to ECU is 23 volts or more, replace ECU (para. 3-468).
Step 7.
Connect CTIS wiring harness electrical lead to pressure transducer.
END OF TESTING!
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