Intake Air Heater: Testing and Inspection

Air Intake Heaters:

1. Turn the ignition switch to the ON position, and verify that the ambient air temperature is less than 60~F (16~C).
2. The WAIT-TO-START lamp will come on for approximately 10 to 20 seconds, if the conditions in step 1. exist, and the air intake heater relays will CLICK. For those 10 to 20 seconds there should be battery voltage at the air intake heater terminals.
3. If there is low battery voltage at these terminals, check for corrosion at the battery terminal, low battery charge level, bad terminal connections, or corrosion in the wiring circuits.
4. Rotate the ignition switch to the OFF position.

CAUTION: Do not energize the the air intake heater relays more than once every 15 minutes. If the relays are cycled, the ignition switch turned OFF, then turned back ON, the engine could be damaged. Wait at least 15 minutes before turning the ignition switch back to the ON position.

NOTE: If the ambient air temperature is greater than 60~F (16~C), then the WAIT-TO-START lamp will not illuminate, and the air intake heaters will not be energized.


5. Disconnect the negative battery cable from the battery.
6. Mark the wires on the air intake heater terminals for assembly. Disconnect air intake heater wires from air intake heater.
7. Using an ohmmeter, test the resistance from each heater terminal to ground. The resistance should be zero (0).
8. If the resistance value is not to specifications, check for dirty or corroded connections, and retest.
9. If the resistance value is still not within specifications, replace the intake heater assembly.