Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
1994 Lexus SC 400FACTORY OEM SERVICE PROCEDURE
Cold Start Injector Circuit
- Turn ignition off. Pull back the right front floor mat. Remove ECM protective cover. Connect Check Harness (09990-01000) to ECM harness, but NOT to ECM. See USING CHECK HARNESS under INTRODUCTION. Disconnect electrical connector from cold start injector time switch. See COMPONENT LOCATIONS under INTRODUCTION. Turn ignition on.
- While cranking engine, measure voltage between chassis ground and terminal No. 78 (Black/Red wire) of ECM connector "B". To identify ECM connectors and terminals, see Figure. If battery voltage is measured, go to step 4).
- If battery voltage is not measured, measure resistance of cold start injector. See COLD START INJECTOR RESISTANCE under COLD START INJECTOR SYSTEM . If resistance is as specified, repair circuit between ECM and cold start injector, or between cold start injector and battery.
- Measure resistance of cold start injector time switch. See COLD START INJECTOR TIME SWITCH RESISTANCE under COLD START INJECTOR SYSTEM . If resistance is as specified, check circuit between cold start injector and cold start injector time switch. If circuit is okay, check cold start injector spray pattern. See COLD START INJECTOR SPRAY PATTERN under COLD START INJECTOR SYSTEM . If spray pattern is okay, cold start injector circuit is okay.
Factory Service Tools
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Disclosure: Verified tool recommendations may earn an affiliate commission at no cost to you.
When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
Rather have a pro handle this?
A certified mobile mechanic comes to your home or office. They bring the tools, you stay comfortable. No tow truck, no waiting room, no surprises.
Comes to youSame-day available12-month warranty
Get a Free QuoteNo obligation. See pricing before you book.