Check FHR Circuit
electrical
Description
A problem was detected in the fuel heater relay coil circuit, shorted when operating and open when not operating; alarm only.
Activation Conditions
A problem has been detected in the fuel heater relay coil circuit. If this alarm occurs while the fuel heater circuit is operating, the circuit is detected shorted. If this alarm occurs while the fuel heater circuit is not operating, the circuit is detected open.
Unit Behavior
Alarm only.
Reset Conditions
Auto reset when the 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 Relay a. Inspect relay socket and connection pins. No damage to relay. No damaged or corroded connections. b. Check resistance of coil (terminals 85 and 86). Refer to Section 2.11 for specifications. 2. Check Power and Wiring a. Check for power at PM-14 as well as fuse F7 terminal A inside PM. Minimum 11 VDC. b. Check fuses F1 and F7. Verify correct fuse (see Figure 2.7). c. Check for power at 1-2MSM-19. d. If the ambient temperature is below 77°F (25°C), 1-2MSM-14 will supply power to the FHR coil, ground will come from 1-2MSM-24. Power up control system in PC mode. (Refer to Section 5.3.2). Check ground from 1-2MSM-24 to FH-D in the FH plug connection and check for power from 1-2MSM-19. If ambient is above 77°F (25°C), place the SROS in the OFF position and check continuity of the wiring from 1-2MSM-24 to the FHR - connection. Good ground. If not, check connectors and wiring between terminals. Verify that there is no damage, moisture or corrosion. e. Check resistance of heater element. Refer to Section 2.11 for specifications.