Taillight Relay Circuit [12/2018 -]: Procedure
WARNING: This page is about a different car, the 2022 Toyota Prius, 2021 Toyota Prius, 2020 Toyota Prius, and 2019 Toyota Prius. However, it is still accessible from the selected car via links, so may be relevant.
- PERFORM ACTIVE TEST USING TECHSTREAM
- Connect the Techstream to the DLC3.
- Turn the power switch on (IG).
- Turn the Techstream on.
- Enter the following menus: Body Electrical / Main Body / Active Test.
- Perform the Active Test according to the display on the Techstream.
Body Electrical > Main Body > Active Test
Tester Display Measurement Item Control Range Diagnostic Note Taillight Relay Taillight relay OFF or ON - Body Electrical > Main Body > Active Test
Tester Display Taillight Relay OK
Taillight relay operates. (Taillights illuminate.)
Result
Proceed to OK NG
Result:
OK
PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE. Refer to PROBLEM SYMPTOMS TABLE [12/2018 -]
Result:
NG
See step 2
- CHECK HARNESS AND CONNECTOR (AUXILIARY BATTERY - INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY)
- Disconnect the 3K instrument panel junction block assembly connector.
- Measure the voltage according to the value(s) in the table below.
Standard Voltage
Tester Connection Condition Specified Condition 3K-1 - Body ground Power switch off 11 to 14 V Result
Proceed to OK NG
Result:
NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
Result:
OK
See step 3
- INSPECT INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY
*a Component without harness connected
(Instrument Panel Junction Block Assembly)- - - Remove the main body ECU (multiplex network body ECU) from the instrument panel junction block assembly.
Refer to REMOVAL [12/2018 - 07/2020] , or refer to REMOVAL [07/2020 -]
- Connect a positive (+) lead from the auxiliary battery to terminal 3K-1.
- Connect a negative (-) lead from the auxiliary battery to terminal MB-14 (TRLY).
- Measure the voltage according to the value(s) in the table below.
Standard Voltage
Tester Connection Condition Specified Condition 3F-32 - Auxiliary battery negative (-) terminal Always 11 to 14 V 3H-30 - Auxiliary battery negative (-) terminal Always 11 to 14 V Result
Proceed to OK NG
Result:
OK
REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU). Refer to REMOVAL [12/2018 - 07/2020] , or refer to REMOVAL [07/2020 -]
Result:
NG
REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY. Refer to REMOVAL [12/2018 - 07/2020] , or refer to REMOVAL [07/2020 -]
- Remove the main body ECU (multiplex network body ECU) from the instrument panel junction block assembly.