Pinout of the Toyota SW20 MR2 Turbo ECU connector (revisions 1–2, 3S-GTE engine) covering key TCCS engine management terminals.
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ECU - Electronic Control Unit Connector.
The 1991–1992 Toyota MR2 Turbo (chassis SW20, revisions 1 and 2) uses a Toyota TCCS (Toyota Computer Controlled System) ECU to manage the 3S-GTE 2.0-litre DOHC turbocharged engine. The TCCS unit integrates sequential fuel injection (SFI), electronic spark advance (ESA), and on-board self-diagnosis across a multi-plug waterproof ECU connector. Diagnostic trouble codes are retrieved by bridging the TE1 and E1 terminals on the check connector and counting flashes of the CHECK ENGINE warning lamp. The ECU architecture and terminal designations are shared with the contemporary ST185 Celica All-Trac, both vehicles using the same 3S-GTE engine family.
Connector A
Pin
name
Signal
A20
Ignition Control Module
RPM
A26
Power Ground
Ground
Connector B
Pin
name
Signal
B3
Intake Air Temperature Sensor
Analog
B4
Engine Coolant Temperature Sensor
Analog
B6
Primary 02 Sensor
Analog
B11
Throttle Position Sensor
Analog
B13
MAP Sensor
Analog
Connector D
Pin
name
Signal
D4
Brake Switch
Analog
D9
Vehicle Speed Sensor
Speed
Notes
The ECU connector is a waterproof multi-plug type; a dedicated engine control check sub-harness (SST) is required for terminal voltage measurement — probing the connector directly risks damaging the waterproof seal.
Connector lock mechanisms include a set bolt that must be torqued to the correct specification on reassembly.
The integrated circuits within the ECU are extremely sensitive to electrostatic discharge; do not open the ECU cover.
To read diagnostic trouble codes: bridge terminals TE1 and E1 on the underbonnet check connector with the ignition on, then count the flashes of the CHECK ENGINE lamp. Each code digit is indicated by 0.25-second pulses; a 1.5-second pause separates digits and a 2.5-second pause separates codes.
Signals
A20 — Ignition timing signal (IGT); RPM-derived pulse output to the ignition control module for electronic spark advance.
A26 — Power ground (E1); main ECU earth reference.
B3 — Intake air temperature sensor input (THA); analogue voltage proportional to inlet air temperature.
B4 — Engine coolant temperature sensor input (THW); analogue voltage used for fuel enrichment and warm-up control.
B6 — Primary oxygen (O2) sensor input; analogue feedback signal for closed-loop air–fuel ratio control.
B11 — Throttle position sensor input (VTA); analogue voltage proportional to throttle valve angle.
B13 — Manifold absolute pressure sensor input (MAP); analogue signal used for load calculation on the turbocharged intake.
D4 — Brake switch input; digital signal indicating brake pedal application.
D9 — Vehicle speed sensor input; pulse signal proportional to road speed, used for idle-up and fuel cut logic.
ECU - Electronic Control Unit Connector.