CTIS Troubleshooting - continued - TM-9-2320-386-24-1-10162

TM 9-2320-386-24-1-1

0019 00

CTIS Troubleshooting (Contd)

MALFUNCTION

TEST OR INSPECTION

CORRECTIVE ACTION

OVERSPEED SIGNAL GENERATOR/LCD BACKLIGHT/LCD HEATER NOT WORKING

Step 1. Turn ignition OFF.

Step 2. Disconnect small pin 4 connector from ECU (overspeed/backlight harness).

Step 3. Turn ignition ON.

Step 4. Measure the voltage on pin 3 with multimeter. Put positive (+) lead on pin 3 and

negative (-) lead to chassis ground. Voltage should read 24 volts with three-position

light switch on BRIGHT; 12 volts on DIM; and 0 volts on OFF position. If voltage is not

present, notify DS maintenance.

Step 5. Measure voltage from pin 4 to ground. This voltage should be 24 volts at all times.

If voltage is not present, notify DS maintenance.

Step 6. Turn ignition OFF.

Step 7. Repeat step 5 to ensure that pin 4 remains at 24 volts (pin 4 supplies voltage to the

LCD heater in the ECU).

Step 8. Disconnect leads from front wiring harness, accessory/battery switch, and overspeed

signal generator.

Step 9. Using the multimeter and extra long test leads, measure pin-for-pin continuity (i.e.,

pin 1 to pin 1, etc.) and measure pin-to-pin continuity (i.e., pin 1 to pin 2, etc.). If shorts

or broken wires are detected, notify DS maintenance.

Step 10. If overspeed/backlight harness is good, reconnect overspeed/backlight to ECU, front

wiring harness, accessory/battery switch, and overspeed signal generator.

Step 11. Measure resistance between leads on signal generator. Resistance should be

193-227 ohms. If resistance is not within this range, replace overspeed signal generator

Step 12. Replace ECU with a known good ECU (WP 0283 00).

END OF TESTING!

ECU FAILS TO OPERATE

Step 1. Perform test 1.

Step 2. If harnesses are good, replace ECU with a known good ECU (WP 0283 00).

END OF TESTING!

CTIS OVERINFLATES TIRE(S)

Check ECU operation.

a. Start engine (TM 9-2320-386-10).

b. Turn ECU OFF, then ON, and cycle ECU from EMERGENCY to HIGHWAY modes.

c. If overinflation continues, repeat step b.

d. If CTIS does not return to normal operation after the third trial, replace ECU

END OF TESTING!

END OF WORK PACKAGE

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