Chart 10 Rear Defogger Inoperative

Chart 10:

Schematic:

CIRCUIT DESCRIPTION
The programmer provides a ground for the defogger relay when it receives a command from the Climate Control Panel (CCP) via the data line. The Body Control Module (BCM) 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.

TEST DESCRIPTION
1. Probing terminal 1 of the relay determines if voltage is available through the circuit breaker to the relay.
2. Probing terminal 2 determines if the relay coil receives voltage from the Heating Ventilation and Air Conditioning (HVAC) fuse.
3. This step determines if the inoperative system is due to the coil circuit of the relay or the switch circuit.
4. This step determines if the fault is due to the relay or the rear defogger grid circuitry.
5. This step determines where the loss of voltage is from.


NOTE: If only part of the defogger grid is inoperative, grid may be repaired with a grid repair kit.