Check Ambient Air Sensor
electrical
Description
Ambient air temperature sensor is out of range -53 to +158°F (-47° to +70° C); 122°F (50°C) is used for calculations.
Activation Conditions
Ambient Air Temperature Sensor (AAT) is not within range of -53 to +158°F (-47° to +70° C).
Unit Behavior
Engine and Electric Operation: A value of 122°F (50°C) will be used for any calculations.
Reset Conditions
Auto reset when sensor is in range 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 Sensor a. Inspect sensor and connector. No damage to sensor. No damage, moisture, or corrosion in connector. b. Check sensor resistance. (Refer to Note 3 in Notes Section) 10,000 Ohms @ 77°F (25°C). Refer to Table 8–5 for chart of resistances for different sensors. 2. Check Sensor Wiring a. Inspect connector pins and terminals at sensor and connector 1-3MSM-1 and 24. (See wiring schematic Section 10.2.) Verify there is no physical damage to harness, and no damage, moisture, or corrosion in connectors. b. Place the system in PC Mode. Refer to Note 2 in Notes Section Disconnect sensor from harness. Check for 3.0 ± 0.1 VDC at harness plug between pins. Voltage should be 3.0 ± 0.1 VDC volts at harness plug between pins. This verifies microprocessor.