DTC P18A7-62: Gear Shift Control Module "A"/"B" IGCT Signal Compare Failure [11/2021 - ]: Procedure
WARNING: This page is about a different car, the 2025 Lexus NX 350h, 2024 Lexus NX 350h, 2023 Lexus NX 350h, and 2022 Lexus NX 350h. However, it is still accessible from the selected car via links, so may be relevant.
- CHECK HARNESS AND CONNECTOR (IGCT TERMINAL VOLTAGE)
Pre-procedure1
- Disconnect the B77 shift control actuator assembly (shift actuator ECU) connector.
- Connect the cable to the negative (-) auxiliary battery terminal.
- Turn the ignition switch to ON.
Procedure1
- Measure the voltage according to the value(s) in the table below.
Standard Voltage
Tester Connection Switch Condition Specified Condition B77-5 (IGCT) - Body ground Ignition switch ON 11 to 14 V Result
Proceed to OK NG Post-procedure1
- Turn the ignition switch off.
- Disconnect the cable from the negative (-) auxiliary battery terminal.
- Reconnect the shift control actuator assembly (shift actuator ECU) connector.
Result:
OK
REPLACE SHIFT CONTROL ACTUATOR ASSEMBLY (SHIFT ACTUATOR ECU). Refer to REMOVAL [11/2021 - ]
Result:
NG
See step 2
- INSPECT IGCT RELAY
Pre-procedure1
- Remove the IGCT relay from the No. 1 engine room relay block and No. 1 junction block assembly.
Procedure1
- Measure the resistance according to the value(s) in the table below.
Standard Resistance
Tester Connection Condition Specified Condition 3 - 5 Auxiliary battery voltage not applied between terminals 1 and 2 10 kΩ or higher 3 - 5 Auxiliary battery voltage applied between terminals 1 and 2 Below 1 Ω *1 IGCT Relay Result
Proceed to OK NG Post-procedure1
- Install the IGCT relay to the No. 1 engine room relay block and No. 1 junction block assembly.
Result:
OK
REPAIR OR REPLACE HARNESS OR CONNECTOR (IGCT POWER SUPPLY CIRCUIT)
Result:
NG
REPLACE IGCT RELAY
- Remove the IGCT relay from the No. 1 engine room relay block and No. 1 junction block assembly.