Toyota Prius 3rd Gen Transmission Control ECU Assembly

Toyota Prius 3 ^rd Generation (XW30)

Transmission Control ECU Assembly Wiring Guide: DIY Pinout Diagram

What is: A Vehicle Transmission Control ECU Assembly (also called a TCM – Transmission Control Module) is an electronic control unit that manages automatic or CVT gearbox operation. It receives input from sensors such as vehicle speed, throttle position, engine load, and gear position. Based on this data, it controls shift timing, gear selection, torque converter lock-up, and line pressure to ensure smooth shifting, better fuel efficiency, and optimal performance.

Transmission Control ECU Assembly (89535-76020)

Toyota Prius 3rd Gen Transmission Control ECU Assembly 89535-76020 front view

Toyota Prius e-CVT control module part number 89535-76020

3rd generation Prius transmission computer unit connector view

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1. Introduction

      The  Toyota Prius 3rd Generation Transmission Control ECU Assembly (89535-76020) is a key electronic module in the hybrid transaxle system. It is specifically designed to manage the electronically controlled CVT (e-CVT) operation used in the Prius hybrid drivetrain.

      This ECU processes signals from speed sensors, shift position sensors, inverter data, and hybrid control inputs. It precisely regulates gear ratio control, motor-generator coordination, and parking lock mechanisms.

      Integrated with the Hybrid Vehicle Control ECU, it ensures smooth power delivery between the gasoline engine and electric motors. The unit improves fuel efficiency, driving comfort, and overall transmission reliability while supporting Toyota’s advanced hybrid system architecture.

1. Related parts and Accessories
   • Hybrid Vehicle Control ECU (HV ECU):-Master controller of the hybrid system. Coordinates engine, motor, and transmission control.
   • Engine Control Module (ECM):-Controls engine performance and shares engine speed/load data.
   • Battery ECU (HV Battery Smart Unit):-Monitors high-voltage battery condition and sends SOC (State of Charge) data.
   • Skid Control ECU (ABS/VSC ECU):-Provides vehicle speed and braking status information.
   • Power Management Control ECU:-Manages overall hybrid energy flow and system coordination.

2. Transmission Control ECU Assembly Wiring Diagram & Pinout

A. Connector Location

• Transmission Control ECU Assembly Position: In the Toyota Prius, the Transmission Control ECU Assembly is mounted inside the cabin, behind the driver-side lower instrument panel, secured to a dashboard support bracket.


• Connector Type:
  • A23 (24 pin) White housing

B. Wiring Table

Transmission Control ECU Assembly (A23)

A23 TERMINALS OF TRANSMISSION CONTROL ECU ASSEMBLY CONNECTOR

Terminal No	Symbol	Wiring (Color Code) & Color	Electrical Paths
A23-1	MWA	(W) White	➳ DA2 8 ➔ D2 7 (MWA) ➤ [Shift Control Actuator Assembly ]
A23-2	MVA	(R) Red	➳ DA2 7 ➔ D2 6 (MVA) ➤ [Shift Control Actuator Assembly ]
A23-3	_	( — ) No Color
A23-4	_	( — ) No Color
A23-5	MUA	(B) Black	➳ DA2 1 ➔ D2 1 (MUA) ➤ [Shift Control Actuator Assembly ]
A23-6	_	( — ) No Color
A23-7	VC	(G) Green	➳ DA1 4 ➔ D2 9 (RVC) ➤ [Shift Control Actuator Assembly ]
A23-8	RB	(GR) Gray	➳ DA1 2 ➔ D2 5 (RB) ➤ [Shift Control Actuator Assembly ]
A23-9	_	( — ) No Color
A23-10	_	( — ) No Color
A23-11	_	( — ) No Color
A23-12	_	( — ) No Color
A23-13	_	( — ) No Color
A23-14	_	( — ) No Color
A23-15	BATT	(SB) Sky Blue	➔ A52 6 ⬌ A53 1 ➔ 1 2 ➤ (BAT) 7.5A Blade Fuse [P CON MAIN] ➔ A52 8 ⬌ A52 5 ➔ AL1 5 ➳ 3A 76 ⬌ 3B 39 ➔ Lb1 5 ➳ b1 6 (IND+) ➤ [Transmission Shift Main Switch]
A23-16	+B	(L) Blue	➔ A55 7 ⬌ A55 12 ➔ 1 2 ➤ 10A Blade Fuse [IGCT NO. 2]
A23-17	RA	(LG) Light Green	➳ DA1 3 ➔ D2 3 (RA) ➤ [Shift Control Actuator Assembly ]
A23-18	_	( — ) No Color
A23-19	E2	(P) Pink	➳ DA1 1 ➔ D2 8 (RE2) ➤ [Shift Control Actuator Assembly ]
A23-20	IND	(R) Red	➔ AL1 6 ➳ 3A 84 ⬌ 3B 36 ➔ LB1 3 ➳ b1 7 (IND-) ➤ [Transmission Shift Main Switch]
A23-21	_	( — ) No Color
A23-22	_	( — ) No Color
A23-23	BMA	B Black	➔ 1G 7 (PCN) ➤ [Integration Relay]
A23-24	_	( — ) No Color

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