Check Glow Plug Relay
engine
Description
The engine preheat enable circuit (EPHT) 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
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: Inspect 3MM and PCM connectors. Verify there is no damage to modules, and no damage, moisture, or corrosion in connector. 2. Check Engine Preheat Enable Circuit a. Using Component Test mode, refer to Section 1.2.4, energize engine preheat circuit. Verify 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. Check for power at 3MM-14. Must have minimum 11 VDC. If not, download data and replace main microprocessor. For replacement instructions refer to Section 1.5.2. c. Check for power at PCM-27. Must have minimum 11 VDC. If not, check wiring and connectors between 3MM-14 and PCM-27. Good continuity, no damage, moisture, or corrosion in connectors. d. Replace PCM. Refer to Section 1.9.16. 3. Is the component functioning? Are there additional alarms? a. If the component is functioning, and additional alarms are present (often within 3MM-01 - 3MM-12 or 3MM-13 - 3MM-18) check related fuses, wires, and connectors. b. If the fuses/wires/connectors are OK, it indicates an internal problem with the MM or the PCM. Download data and replace main microprocessor. For complete Main Microprocessor Module replacement instructions refer to Section 1.5.2. c. If problem persists reinstall the old MM, and replace the PCM. Refer to Section 1.9.16.