Cold Start Injector Circuit

2012 Lexus IS 250C V6-2.5L (4GR-FSE)SECTION Cold Start Injector Circuit




4GR-FSE ENGINE CONTROL: SFI SYSTEM: Cold Start Injector Circuit
- Cold Start Injector Circuit

DESCRIPTION

The cold start injector is attached to the intake air surge tank and is designed to improve start-ability when the engine is cold. It operates when the engine coolant temperature is -12°C (10°F) or less, and the starter signal is on.

WIRING DIAGRAM





INSPECTION PROCEDURE

NOTICE:
Inspect the fuses for circuits related to this system before performing the following inspection procedure.

PROCEDURE

1. INSPECT COLD START INJECTOR

(a) Inspect the cold start injector Testing and Inspection.

NG -- REPLACE COLD START INJECTOR Removal
OK -- Continue to next step.

2. INSPECT ECM (STJ1 VOLTAGE)

(a) Turn the engine switch on (IG).





(b) Measure the voltage according to the value(s) in the table below.

Standard Voltage:





Text in Illustration





NG -- CHECK HARNESS AND CONNECTOR (COLD START INJECTOR - ECM)

OK -- REPLACE ECM Removal

3. CHECK HARNESS AND CONNECTOR (COLD START INJECTOR - ECM)

(a) Disconnect the cold start injector connector.

(b) Disconnect the ECM connector.

(c) Measure the resistance according to the value(s) in the table below.

Standard Resistance (Check for Open):





Standard Resistance (Check for Short):





(d) Reconnect the ECM connector.

(e) Reconnect the cold start injector connector.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR

OK -- REPAIR OR REPLACE HARNESS OR CONNECTOR (IG2 RELAY - COLD START INJECTOR)
RENDER: 1.0x

NO RELATED

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • β€’ You smell fuel, burning insulation, or see smoke.
  • β€’ Brakes feel soft, pull hard to one side, or make grinding noises.
  • β€’ The engine overheats, stalls repeatedly, or misfires under load.
  • β€’ You are missing required tools, torque specs, or safe lifting equipment.
  • β€’ You are not confident in the next step or safety outcome.