Check Prestart (Glow Plug)
engine
Description
The prestart relay output and FET feedback voltage do not match, and the unit alarms only.
Activation Conditions
Trigger On: Prestart relay output is ON and FET Feedback Voltage is below minimum ON threshold OR Prestart relay output is OFF and FET Feedback voltage is above maximum ON threshold Trigger Off: If alarm was active when Prestart Output was ON, trigger OFF if Output is ON and FET Feedback Voltage is sensed in Active range OR If alarm was active when Prestart 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
Alarm reset OR Cycle Power
Corrective Actions
1. Check System Values in Cabin Tech to verify if the glow plug output is ON/OFF when the fault occurs. a. If fault occurs when the glow plug output is ON, go to step 2 b. If fault occurs when glow plug output is OFF, go to step 3 2. Check glow plugs/wiring for open circuit a. Check glow plug resistance – refer to table? b. Check wiring from J2-2 to glow plugs for open circuit c. If OK go to step 4 3. Check glow plug wiring for short to power a. Is voltage at glow plugs > 5.0 VDC when glow plug output is OFF b. Remove glow plug wire from J2-2. Is voltage at glow plugs > 0.5 VDC? c. If voltage is < 0.5 VDC go to step d. If voltage is > 0.5 VDC, check for short to power in harness between APU module and glow plugs 4. Replace APU module - Replace APU module – Refer to section