Check Engine Preheat Enable Circuit
engine
Description
Engine preheat enable circuit fault: the EPHT circuit is shorted when energized or open at other times, and the unit gives alarm only.
Activation Conditions
A problem has been detected in the engine preheat enable circuit (EPHT). If this alarm is activated when the circuit is energized, the circuit is detected shorted. If this alarm is activated at any other time, the circuit is detected open.
Unit Behavior
Engine and Electric Operation: Alarm only.
Reset Conditions
Auto reset when circuit is normal, or alarm may be manually reset using the display mounted keys or by turning the unit off, then back on again.
Corrective Actions
1. Check EPHT Wiring - Verify there is no damage to modules, and no damage, moisture, or corrosion in connector. 2. Check Engine Preheat Enable Circuit Using Component Test mode, refer to Section 5.2.4, energize engine preheat circuit. The circuit is energized and amp draw is displayed. NOTICE DO NOT leave the air intake circuit energized for the full five minutes if full amperage is shown, as the intake air heater element life will be greatly shortened. b.