Intake Air Heater Test

CAUTION: When testing, do not energize the air heater relays more than once per 15 minutes without running and operating the engine. Due to the high amperage needed to operate the heater, the batteries may not have enough time to recharge. Wait 15 minutes before turning the key back to the ON position.

1. With the engine not running and ambient air temperature below 16°C (60°F), turn the ignition key to the ON position.
2. The wait-to-start warning lamp will come on and the air heater relays should click ON signaling the start of the preheat cycle.

Air Heater:

3. Check for battery voltage at both air heater terminals. The heater will only be energized for 10 to 20 seconds.

Air Heater Cycle Chart:

Refer to the Preheat Cycle Time Interval Chart.

HEATER TEST
1. Disconnect both negative battery cables at both batteries.

Air Heater:

2. Lift the rubber shields from each of the cable connectors at the intake manifold air heater to expose the cable terminals. Do not disconnect cable nuts.
3. Use an ohmmeter to test the resistance between the cable terminal (not the mounting stud) and a ground. The resistance should be zero (0). If not, inspect for corroded or dirty cable connections. Clean or repair the connections and retest before replacing heater. Also check both ends of the ground cable at the rear of the heater for corroded or dirty connections. If resistance is now anything other than zero (0), proceed to next step.
4. Disconnect both cables from the intake manifold heater (two nuts).
5. Measure the resistance from each of the air heater terminal threaded studs to a ground. The resistance should be zero (0). If the ohmmeter is still reading anything other than zero (0), replace the intake manifold air heater.
6. After testing and repairing, connect battery cables to both batteries.