Chart 7 Improper Rear Defogger Operation
Chart:
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 limited to 5 minute intervals thereafter, until a new ignition cycle occurs.
TEST DESCRIPTION
Numbers below refer to circled numbers on the diagnostic chart.
1. This step checks to see if CKT 291 is grounded.
2. This step checks for a short to voltage on CKT 293.
3. This step checks to see if the programmer is grounding CKT 291.
4. This step checks to see if the rear defogger relay is receiving power.
5. This step checks to see if the circuit breaker is receiving power.
6. This step checks to see if the programmer is grounding the rear defogger relay coil.
7. This step bypasses the rear defogger relay to see if the grid will operate.