DESCRIPTION When the air conditioning control assembly (rear window defogger switch) is turned on, a rear window defogger activation request signal is sent via the LIN communication line to the air conditioning amplifier. Then the air conditioning amplifier operates the rear window defogger. WIRING DIAGRAM CAUTION / NOTICE / HINT HINT: This circuit uses the LIN communication line. Before performing the inspection, check that the LIN communication system is functioning normally (see page ). NOTICE: Inspect the fuses for circuits related to this system before performing the following procedure. PROCEDURE
(a) Select the Active Test, using the Techstream to generate a control command, and then check that the rear window defogger operates (See page ). Air Conditioner
OK: Rear window defogger operates normally.
(a) Temporarily replace the air conditioning control assembly with a new or normally functioning one (See page ). (b) Check that the malfunction disappears. OK: Malfunction disappears.
(a) Remove the defogger relay (DEF) from the engine room relay block, junction block. (b) Measure the resistance according to the value(s) in the table below. Standard Resistance:
(a) Remove the defogger relay (DEF) from the engine room relay block, junction block. (b) Disconnect the J19 air conditioning amplifier connector. (c) Measure the voltage according to the value(s) in the table below. Standard Voltage:
(d) Measure the resistance according to the value(s) in the table below. Standard Resistance:
(a) Disconnect the P9 and P10 rear window glass (defogger wire) connectors. (b) Remove the defogger relay (DEF) from the engine room relay block, junction block. (c) Measure the resistance according to the value(s) in the table below. Standard Resistance:
(a) Perform the on-vehicle inspection, check that the window defogger system operates normally (See page ). OK: Malfunction disappears.
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Toyota Tundra Service Manual > Occupant Classification System: Front Occupant Classification Sensor RH Circuit Malfunction (B1781)
DESCRIPTION The front occupant detection sensor RH circuit consists of the occupant classification ECU and the front occupant detection sensor RH. DTC B1781 is set when a malfunction is detected in the front occupant detection sensor RH circuit. DTC Code DTC Detection Condition Trouble Area B1781 On ...