Check Alt Enable Circuit
electrical
Description
The Alt Enable circuit feedback is out of range; the unit gives an alarm only.
Activation Conditions
Trigger On Alt Enable FET is ON and FET Feedback Voltage is below Minimum ON Threshold OR ALT Enable FET is OFF and FET Feedback Voltage is above Maximum OFF Threshold. Trigger Off If alarm was active when ALT Enable Output was ON, trigger OFF if Output is ON and FET Feedback Voltage is sensed in Active range OR If alarm was active when ALT Enable Output was OFF, trigger OFF if Output is OFF and FET Feedback Voltage is sensed in Inactive range OR If alarm was active when Glow Plug Output was OFF, trigger OFF if Output is OFF and FET Feedback Voltage is sensed in Inactive range OR Alarm Reset OR Cycle Power
Unit Behavior
Alarm only
Reset Conditions
See manual.
Corrective Actions
1. Verify if condition occurs when ALT Enable output is ON or OFF a. Check Alternator power output status in System Values menu in CabinTech b. If status is ON go to step 2. c. If status in OFF go to step 4. 2. Inspect Harness a. Inspect APU harness and connections between APU J2-5 and ALT IG. Connections must be free of corrosion, moisture, and terminal connections secure 3. Check harness continuity between APU J2-5 and ALT IG – must be less than 1.0 Ω 4. Replace APU module