Back-up Power Source Circuit: Procedure

1. Remove the A/C NO. 1 fuse from the instrument panel junction block.
2. Measure the resistance of the fuse.

   Standard resistance

   Tester Connection	Condition	Specified Condition
   A/C NO. 1 fuse	Always	Below 1 Ω

NG → REPLACE FUSE 

OK: Go to next step 

1. Disconnect the D37 and D38 amplifier connectors.
   Fig 1: Checking Harness And Connector (Air Conditioning Amplifier - Battery)

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Measure the voltage according to the value(s) in the table below.

   Standard voltage

   Tester Connection	Condition	Specified Condition
   D37-21 (B) - Body ground	Always	11 to 14 V
   D38-24 (+B2) - Body ground	Always	11 to 14 V

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

1. Disconnect the D37 and D38 amplifier connectors.
   Fig 2: Checking Harness And Connector (Air Conditioning Amplifier - Body Ground)

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Measure the resistance according to the value(s) in the table below.

   Standard resistance

   Tester Connection	Condition	Specified Condition
   D37-14 (GND) - Body ground	Always	Below 1 Ω
   D38-20 (GND2)* - Body ground	Always	Below 1 Ω

   HINT: 

   *: w/ Rear air conditioning

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK → See step   4