Test B: DTC B1255 Or B1257 - Air Temperature External Sensor Circuit Open Or Short To Ground
PINPOINT TEST B: DTC B1255 OR B1257 - AIR TEMPERATURE EXTERNAL SENSOR CIRCUIT OPEN OR SHORT TO GROUNDNormal Operation
Under normal operation, the ambient air temperature sensor receives a ground from the HVAC module - dual automatic temperature control (DATC) through circuit RH111 (GY/BU). A 5-volt reference voltage is supplied to the ambient air temperature sensor from the HVAC module - DATC through circuit VH407 (YE/GN).
- 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.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Ambient air temperature sensor
- HVAC module - DATC
B1-B3:
B4-B5:
