Installation of an Adaptronic ECU for a Lexus LS400/SC400 1UZFE Engine

Although documentation exists for installation for a Toyota Soarer (SC400), there are none specifically for a LS400 (Celsior) motor.

My particular application does not require retaining the OEM ECU; however if yours does, I recommend following the directions for the Soarer installation when referring to the section titled “Fooling the Factory ECU to eliminate fault code generation”.  Specifically the ignition and air flow directions.

The early LS400 wiring harness contains 4 plugs that connect to the OEM ECU.  According to the 1992 LS400 Electrical Wiring Diagram, these are referred to plugs A, B, C, and D.

Only some of these wires are actually needed to connect to the four plugs for the Adaptronic.

What we are looking for in the original LS400 wiring diagram are for these sensors, inputs, and outputs that are required for operation.  Here is each LS400 plug individually.

LS400 Plug A

Of the pins listed above, the following use the same pin type and can be swapped as seen below.

VTA1 (TPS signal)                             Water temp signal

B+ (+12V Ignition)                             E1 (Gnd)

E2 (TPS Gnd) and VC (TPS +5V) do not have the same pins and must be wired conventionally by soldering or so other means of secure connection.

 Some of the other plugs utilize the same pins as well and may allow for pin swapping.  Others must be direct connected due to the larger pin.  If you choose to piggyback with the OEM ECU because of your application, you will want to tap some of the connections instead of swapping the pins.  This is noted in the Standalone/Piggyback columns.

Please keep in mind this is only a recommendation.  Take the time to review the wiring diagrams for your specific application.

LS400 Plug B

LS400 Plug C

On Plug C, the IDL pin can optionally be used as one of the eight Dig in’s.  Also the G- and NE- are connected together in the harness, only one needs to connect to the Adaptronic, remove the other completely or wire G- and NE- together.

Also note the IGT’s.  If using as a piggyback, see Soarer install directions.

LS400 Plug D

For simplicity, I chose to use a standard GM IAT sensor and a standard GM 1 bar MAP sensor.  Their installation is also very easy.

For simplicity, I chose to use a standard GM IAT sensor and a standard GM 1 bar MAP sensor since both are cheap and easy to find.  Their installation is also very easy.  Based on the sensor resistance, I created values for the air temp calibration.  Not exact, but works pretty well.

For the Water temp sensor, I kept the OEM sensor and calibrated it to match.  I also used sensor resistance to match up values and this has work pretty well so far.

Air Temperature

Both of the temperature sensor calibrations are approximates and may need some adjustment based on your application

Water Temperature

Adaptronic Plugs

Update: For all 1UZFE owners, you have to install this specific UZFE Data into the Adaptronic before the ECU can work.