Heater comes up short.

How to Tell

If you suspect a short, use an ohmmeter to test for it like this:

1. Connect the positive lead to Pin 1 of the P4 terminal and the negative lead to ground on the heater chassis.

2. If the ohmmeter reads less than one megohm, remove the knurled nut that holds the control box cover in place and remove the cover.

3. If resistance increases to above one megohm and remains steady at high impedance, you've got a short.

What To Do

To fix the short follow these steps:

1. Unplug the two wires from the connector on the glow plug resistor. Wrap each of the wires and their connectors with heat shrink tubing, NSN 5970-00-815-1295. Then use a heat gun or blow dryer to shrink the tubing in place.

2. Flip the two wires over and reconnect them to the glow plug resistor terminal. That puts a little more space between the wires and the control box cover.

It's very important to avoid loosening or removing the glow plug resistor screw when flipping the wires. The screw goes all the way through the ceramic insulator and is used to hold several other parts in place. Loosening the screw could result in a short to ground.

3. Push down on the wires to provide as much space as possible between them and the control box cover. Reinstall the cover.