Chart 8 Rear Defogger Inoperative

CIRCUIT DESCRIPTION

The ECC programmer provides a ground for the defogger relay when it receives a command from the IPC via the data line. The IPC times the operation initially for 10 minutes, then commands the programmer to deactivate the relay ground. Additional requests for rear defogger are for 5 minute intervals, thereafter until a new ignition cycle occurs.

1. This step checks to see if the rear defog relay switch is receiving power.

2. This step checks to see if the rear defogger relay coil is receiving power.

3. This step checks rear defog relay for proper operation.

4. This step identifies if an open in the power source an open in the ground to the rear defogger is causing to the problem.

5. Checks CKT 291 for an open.

6. This step decides if relay is faulty.