Test A: DTC B1249 - Blend Door Failure Or Short

PINPOINT TEST A: DTC B1249 - BLEND DOOR FAILURE OR SHORT

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Normal Operation
Under normal operation, the temperature blend door actuator motor is supplied voltage or ground on circuit 245 (BN/LG), depending on desired actuator rotation, by the electronic automatic temperature control (EATC) module. The EATC module then supplies the appropriate voltage or ground to the other side of the actuator motor on circuit 246 (VT).

The temperature blend door actuator feedback resistor is supplied a ground from the EATC module by circuit 438 (RD/WH) and a 5 volt reference voltage on circuit 600 (DB). The EATC module reads the voltage on circuit 437 (YE/LG) to determine the actuator position by the position of the actuator feedback resistor wiper arm.

Possible Causes
- An open, short to voltage, ground or together in circuits 245 (BN/LG), 246 (VT), 600 (DB), 437 (YE/LG) or 438 (RD/WH)
- Temperature blend door actuator
- Electronic automatic temperature control (EATC) module
- Stuck or bound linkage or door