Where is the fuel pump ECU on a Lexus sc400?
The SC400 does not have a standalone “fuel pump ECU.” The fuel pump is controlled by the engine control module (ECM) through a fuel pump relay in the engine bay fuse/relay box, and the pump itself is located in the fuel tank.
How the fuel system is configured in the SC400
The ECM governs engine operation and fuel delivery, while the fuel pump is powered by a relay that the ECM energizes when ignition is on and fuel pressure is needed. There is no dedicated fuel pump ECU module in standard SC400 models. The pump itself resides in the fuel tank as part of the in-tank module.
Why this matters for diagnosing fuel issues
Knowing there isn’t a separate FP ECU helps you target troubleshooting toward the relay, wiring, grounds, and the pump module rather than chasing an elusive control unit. Start by verifying power, ground, and signal integrity in the relay circuit and pump harness.
Where to look for fuel pump components
When diagnosing fuel delivery on a Lexus SC400, focus on these key locations and components. The list below highlights the most common points of failure and where to inspect them.
- Under-hood fuse/relay box: Main housing for the fuel pump relay; usually mounted in the engine bay on the driver's side near the strut tower.
- Fuel pump relay: A relay labeled “FUEL PUMP” inside the engine bay fuse box; it energizes the in-tank pump when the ECM requests fuel pressure.
- Inertia switch (if equipped): Some models include an inertia switch that cuts power to the pump after a collision; location varies by year and market.
- In-tank fuel pump module: Located inside the fuel tank; contains the pump, sending unit, and related connectors; access may require lowering the tank or removing rear seats depending on the exact model year.
- ECM wiring and grounds: Inspect relevant harnesses and grounds related to the fuel-pump circuit if electrical symptoms persist.
Inspecting these components helps determine whether the issue lies with power delivery, a faulty relay, or the pump assembly itself.
Practical diagnostic steps
Use a systematic approach to diagnose fuel-pump operation on the SC400. The steps below are designed to verify that the pump receives power and the ECM properly controls it.
- Check battery voltage and grounding to confirm the system has a proper power supply.
- Test the fuel pump relay for continuity and coil resistance; swap with a known-good relay if possible.
- With ignition on and engine off, measure voltage at the fuel-pump connector; if there is no voltage, trace back through the relay and wiring to find the fault.
- Inspect the in-tank pump module for wear, clogs, or failures; low pressure or no flow despite voltage may indicate a failed pump.
- Scan for ECM or sensor trouble codes that could affect fuel pressure regulation or pump control.
Note: Fuel-system work carries fire and leak risks. If you’re not comfortable performing these tests, consult a qualified technician and use OEM-spec parts and procedures.
Summary
There is no separate fuel pump ECU on the Lexus SC400. The pump is controlled by the ECM via a fuel pump relay located in the engine bay fuse/relay box, and the pump itself is housed in the in-tank module. For troubleshooting, focus on the relay, wiring, and pump assembly rather than searching for a distinct ECU dedicated to the fuel pump.
Where is the ECU on a Lexus?
So that's step number one i believe we're going to start. Off. By just getting our pry tools in here. And gently prying our panel off. And then push it back towards the front of the car. We're out.
Is the fuel pump controlled by the ECU?
The Fuel Pump function is used where the ECU will be controlling an electric Fuel Pump.
Where is the fuel pump ECU on a 1993 Lexus LS400?
The Fuel Pump Electronic Control Unit, situated in the right rear of the passenger compartment (trunk), regulates the fuel pump output.
Where is the fuel pump control module located?
The fuel pump control module is typically located on the rear underside of the vehicle, often near the fuel tank. On trucks, it is commonly found mounted to the frame rail above the spare tire, and on SUVs or cars, it may be under the rear seat, near the gas tank, or mounted to the front crossmember. To find it, you may need to consult your vehicle's manual or look for a black box-like component labeled with names like FSCM or FPDM.
This video shows the location of the fuel pump control module on GM vehicles: 59sNuts & Bolts with ToneYouTube · Oct 26, 2023
- Common locations:
- Trucks: Mounted to the frame rail above the spare tire.
- SUVs/Cars: Under the rear seat, behind the gas tank, or attached to the front crossmember.
- How to identify it: It usually looks like a small black or gray box and may be labeled "FSCM" or "FPDM".
- How to access it: Accessing the module often requires removing or lowering the spare tire or removing other parts like shields or carpeting to get to it.
This video demonstrates the replacement of a fuel pump control module on a 2019 Ford F350: 58sRevit AutoYouTube · Nov 5, 2021
