Ignition Circuit [11/2021 - 03/2023]: Procedure
WARNING: This page is about a different car, the 2025 Lexus NX 250, 2024 Lexus NX 250, 2023 Lexus NX 250, and 2022 Lexus NX 250. However, it is still accessible from the selected car via links, so may be relevant.
- CHECK TERMINAL VOLTAGE (POWER SOURCE OF IGNITION COIL ASSEMBLY)
- Disconnect the ignition coil assembly connectors.
- Turn the ignition switch to ON.
- Measure the voltage according to the value(s) in the table below.
Standard Voltage
Tester Connection Condition Specified Condition B5-1 (+B) - B5-3 (GND) Ignition switch ON 11 to 14 V B6-1 (+B) - B6-3 (GND) Ignition switch ON 11 to 14 V B7-1 (+B) - B7-3 (GND) Ignition switch ON 11 to 14 V B8-1 (+B) - B8-3 (GND) Ignition switch ON 11 to 14 V Result
Proceed to OK NG
Result:
NG
See step 3
Result:
OK
See step 2
- CHECK HARNESS AND CONNECTOR (IGNITION COIL ASSEMBLY - ECM)
- Disconnect the ignition coil assembly connectors.
- Disconnect the ECM connector.
- Measure the resistance according to the value(s) in the table below.
Standard Resistance
Tester Connection Condition Specified Condition B5-2 (IGT1) - B50-49 (IGT1) Always Below 1 Ω B6-2 (IGT2) - B50-48 (IGT2) Always Below 1 Ω B7-2 (IGT3) - B50-47 (IGT3) Always Below 1 Ω B8-2 (IGT4) - B50-46 (IGT4) Always Below 1 Ω B5-2 (IGT1) or B50-49 (IGT1) - Body ground and other terminals Always 10 kΩ or higher B6-2 (IGT2) or B50-48 (IGT2) - Body ground and other terminals Always 10 kΩ or higher B7-2 (IGT3) or B50-47 (IGT3) - Body ground and other terminals Always 10 kΩ or higher B8-2 (IGT4) or B50-46 (IGT4) - Body ground and other terminals Always 10 kΩ or higher Result
Proceed to OK NG
Result:
OK
REPLACE ECM. Refer to REMOVAL [11/2021 - ]
Result:
NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
- CHECK HARNESS AND CONNECTOR (IGNITION COIL ASSEMBLY - BODY GROUND)
- Disconnect the ignition coil assembly connectors.
- Measure the resistance according to the value(s) in the table below.
Standard Resistance
Tester Connection Condition Specified Condition B5-3 (GND) - Body ground Always Below 1 Ω B6-3 (GND) - Body ground Always Below 1 Ω B7-3 (GND) - Body ground Always Below 1 Ω B8-3 (GND) - Body ground Always Below 1 Ω Result
Proceed to OK NG
Result:
NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
Result:
OK
See step 4
- CHECK HARNESS AND CONNECTOR (IGP NO. 1 RELAY - IGNITION COIL ASSEMBLY)
- Disconnect the IGP NO. 1 relay from No. 1 engine room relay block and No. 1 junction block assembly.
- Disconnect the ignition coil assembly connectors.
- Measure the resistance according to the value(s) in the table below.
Standard Resistance
Tester Connection Condition Specified Condition 3 (IGP NO. 1 relay) - B5-1 (+B) Always Below 1 Ω 3 (IGP NO. 1 relay) - B6-1 (+B) Always Below 1 Ω 3 (IGP NO. 1 relay) - B7-1 (+B) Always Below 1 Ω 3 (IGP NO. 1 relay) - B8-1 (+B) Always Below 1 Ω 3 (IGP NO. 1 relay) or B5-1 (+B) - Body ground and other terminals Always 10 kΩ or higher 3 (IGP NO. 1 relay) or B6-1 (+B) - Body ground and other terminals Always 10 kΩ or higher 3 (IGP NO. 1 relay) or B7-1 (+B) - Body ground and other terminals Always 10 kΩ or higher 3 (IGP NO. 1 relay) or B8-1 (+B) - Body ground and other terminals Always 10 kΩ or higher Result
Proceed to OK NG
Result:
OK
GO TO ECM POWER SOURCE CIRCUIT. Refer to ECM Power Source Circuit [11/2021 - ]
Result:
NG
REPAIR OR REPLACE HARNESS OR CONNECTOR