B1417

AIR CONDITIONING: AIR CONDITIONING SYSTEM: B1417/17: Rear Evaporator Temperature Sensor Circuit

DTC B1417/17 - Rear Evaporator Temperature Sensor Circuit

DESCRIPTION

The No. 2 cooler thermistor (rear evaporator temperature sensor) is installed on the evaporator in the rear cooler unit to detect the cooled air temperature that has passed through the evaporator and control the air conditioning. It sends appropriate signals to the rear junction block ECU and the air conditioning amplifier via the CAN communication line. The resistance of the No. 2 cooler thermistor (rear evaporator temperature sensor) changes in accordance with the cooled air temperature that has passed through the rear evaporator. As the temperature decreases, the resistance increases. As the temperature increases, the resistance decreases.
The air conditioning amplifier applies voltage (5 V) to the No. 2 cooler thermistor (rear evaporator temperature sensor) and reads voltage changes as the resistance of the No. 2 cooler thermistor (rear evaporator temperature sensor) changes. This sensor is used for frost prevention.
HINT: This circuit uses the CAN communication line. Before performing the inspection, check that the CAN communication system is functioning normally.





WIRING DIAGRAM





INSPECTION PROCEDURE

PROCEDURE

1. READ VALUE USING INTELLIGENT TESTER OR TECHSTREAM (EVAPORATOR FIN THERMISTOR)
(a) Use the Data List to check if the evaporator fin thermistor is functioning properly.
(1) Intelligent tester

AIR CONDITIONER





(2) Techstream

Air Conditioner





OK:
The display is as specified in the normal condition.
NG -- INSPECT NO. 2 COOLER THERMISTOR (REAR EVAPORATOR TEMPERATURE SENSOR)
OK -- REPLACE AIR CONDITIONING AMPLIFIER
2. INSPECT NO. 2 COOLER THERMISTOR (REAR EVAPORATOR TEMPERATURE SENSOR)





(a) Remove the No. 2 cooler thermistor (rear evaporator temperature sensor) connector Disassembly.
(b) Measure the resistance according to the value(s) in the table below.
Standard resistance:





NOTICE:
- Even slightly touching the sensor may change the resistance value. Be sure to hold the connector of the sensor.
- When measuring, the sensor temperature must be the same as the ambient temperature.
HINT: As the temperature increases, the resistance decreases (see the graph).

NG -- REPLACE NO. 2 COOLER THERMISTOR (REAR EVAPORATOR TEMPERATURE SENSOR)
OK -- Continue to next step.
3. CHECK HARNESS AND CONNECTOR (REAR AIR CONDITIONING HARNESS - REAR JUNCTION BLOCK ECU)





(a) Disconnect the S28 rear air conditioning harness connector.
(b) Disconnect the S62 and LA rear junction block ECU connectors.
(c) Measure the resistance according to the value(s) in the table below.
Standard resistance:






NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.
4. REPLACE REAR AIR CONDITIONING HARNESS
(a) Replace the rear air conditioning harness with a normal one and check that the condition returns to normal Disassembly.
OK:
Same problem does not occur.
NG -- REPLACE REAR JUNCTION BLOCK ECU
OK -- Continue to next step.
5. RECHECK DTC
(a) Clear the DTCs DTC Check / Clear.
(b) Check for DTCs DTC Check / Clear.
OK:
DTC B1417 is not output.
NG -- REPLACE REAR JUNCTION BLOCK ECU
OK -- END (REAR AIR CONDITIONING HARNESS IS DEFECTIVE)