Pinpoint Test 2: DTC B1255 Or B1257 - Air Temperature External Sensor Circuit Open Or Short To Ground
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PINPOINT TEST 2: DTC B1255 OR B1257 - AIR TEMPERATURE EXTERNAL SENSOR CIRCUIT OPEN OR SHORT TO GROUND - HYBRID
Normal Operation
The ambient air temperature sensor receives a ground from the dual automatic temperature control (DATC) module through circuit (GY/L). A 5-volt reference voltage is supplied to the ambient air temperature sensor from the DATC module through circuit (Y/G).
- DTC B1255 (Air Temperature External Sensor Circuit Open) - The module senses no voltage drop on the sensor reference voltage circuit, indicating an open circuit.
- DTC B1257 (Air Temperature External Sensor Circuit Short To Ground) - The module senses excessive voltage drop on the sensor reference voltage circuit, indicating a short directly to ground.
Possible Causes
- Wiring, terminals or connectors
- Ambient air temperature sensor
- DATC module
Diagnostic Procedure
Step 1-Step 4:
