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 300 AutomaticFACTORY OEM SERVICE PROCEDURE
Connecting Tachometer
CAUTION:
Ensure tachometer is compatible with ignition system. DO NOT allow tachometer terminal (IG-) to become grounded, as it could result in damage to ignitor and/or ignition coil.
Connect tachometer between chassis ground and terminal IG- of DLC No. 1. See Figure. See COMPONENT LOCATIONS .
COMPONENT LOCATIONS
| Component | Location |
|---|---|
| ACIS-Intake Air Control Valve (IACV) & Actuator | On center of air intake chamber. See Figure. |
| ACIS Vacuum Switching Valve (VSV) | Above starter motor, on top of ACIS vacuum tank. |
| ACIS Vacuum Tank | Above starter motor. See Figure and Figure. |
| Air Intake Chamber | On left side of cylinder head, bolted to intake manifold. See Figure. |
| AM2 Fuse (30-Amp) | Behind battery, in fuse block. |
| Clutch Start Switch (M/T) | At top of clutch pedal. |
| Data Link Connector (DLC) No. 1 | On front end of air intake chamber. See Figure. |
| EFI Fuse (30-Amp) | Behind battery, in fuse/relay block. |
| EFI Main Relay | Behind battery, in fuse/relay block. |
| EGR Temperature Sensor | Next to EGR valve, on EGR pipe. |
| EGR Vacuum Modulator | On left side of cylinder head, above EGR valve. See Figure. |
| EGR Vacuum Switching Valve (VSV) | Between cylinder head and front end of air intake chamber, on bracket. |
| EGR Valve | On left side of cylinder head, near firewall. |
| Engine Control Module (ECM) | Under right front floor mat and protective cover. |
| Engine Coolant Temp. (ECT) Sensor | On water outlet, where upper radiator hose is connected to engine. |
| EVAP (Charcoal) Canister | In right rear corner of engine compartment. |
| EVAP Check Valve For EVAP (Charcoal) Canister | On end of hose at bottom of canister. |
| EVAP Check Valve For Vacuum Circuit | Below intake air connector. |
| EVAP Vacuum Switching Valve (VSV) | On left side of engine, above starter motor. |
| Fuel Filter | Under rear end of vehicle, near muffler, behind protector plate. |
| Fuel Pressure Pulsation Damper | On left side of cylinder block, near starter. |
| Fuel Pressure Regulator | On front end of fuel rail. |
| Fuel Pressure Regulator Vacuum Switching Valve (VSV) | At front end of air intake chamber, on bracket. |
| Fuel Pump | In fuel tank (accessible with rear seat back removed, but connector is accessible through luggage compartment). |
| Fuel Pump Connector | In front left corner of luggage compartment. |
| Fuel Pump ECU | Under left rear window, behind trim panel (remove seat for access). |
| Idle Air Control (IAC) Valve | On throttle body. |
| Ignitor | On left front strut tower. |
| Ignition Coil | On right front strut tower. |
| IGN Fuse (7.5-Amp) | Behind left side of instrument panel, in fuse block. |
| INJ Fuse (30-Amp) | Behind battery, in fuse/relay block. |
| Intake Air Connector | Split tube between throttle body and air intake chamber. See Figure. |
| Intake Air Control Valve (IACV) & Actuator (For ACIS) | On center of air intake chamber. See Figure. |
| Intake Air Temp. (IAT) Sensor | Part of Volume Airflow (VAF) sensor. |
| Knock Sensors | On left side of cylinder block. |
| Oxygen Sensor (Main) | One on each exhaust manifold piece. |
| Oxygen Sensor (Sub - Calif.) | Near rear catalytic converter. |
| Park/Neutral Position (PNP) Switch | On right side of transmission, at front. |
| PCV Valve | On top of valve cover, at rear end. |
| Starter Relay | Behind battery, in fuse/relay block. |
| ST Fuse (7.5-Amp) | Behind left side of instrument panel, in fuse block. |
| Sub-Throttle Actuator Motor (With TRAC) | On throttle body. See Figure. |
| Vehicle Speed Sensor (VSS) No. 1 (A/T) | On left side of transmission, with a 3-wire connector (do not confuse with VSS No. 2, which has a 2-wire connector). See Figure. |
| Vehicle Speed Sensor (VSS) No. 1 (M/T) | On right side of transmission. See Figure. |
| Volume Airflow (VAF) Sensor | In intake air hose. |
Factory Service Tools
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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.
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