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6M-GEU MZ12 Soarer Engine Wiring

Page history last edited by wilbo666 3 weeks, 3 days ago

 


 

Introduction

This page provides information in regards to 6MGEU engine wiring as found in the Japanese MZ12 Toyota Soarer.

 

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MZ12 Toyota Soarer 6MGEU Engine ECU Part Numbers

Toyota Part Number
Dates
Transmission
89661‑30120 01/1985 to 11/1985

Automatic Transmission

89661‑24070

01/1985 to 11/1985 Manual Transmission

 

MZ12 Toyota Soarer 6MGEU Engine ECU Pinout

 

 

 

Note: Blue text indicates terminals related to automatic transmission functions only.

Plug Pin Number Symbol Definition Input / Output What Why How Link
90980-10294 1 NSW / CSW
Neutral Switch / Clutch Switch
Input This pin is used to determine if the transmission is in the Neutral position (Park or Neutral for automatic transmissions, Clutch in for manual transmissions). The engine ECU can vary the required idle speed as required when the vehicle is in Neutral (i.e increase idle RPM when A/C is on and in Neutral). This pin is connected to Ground by the automatic shifter position switch and the Starter motor when the automatic transmission shifter is in the 'N' or 'P' positions.   In manual transmission vehicles this pin is connected to ground when the clutch pedal is not depressed.  In manual vehicles this pin is connected to the engine ECU STA pin.  
90980-10294 2  /  /  /  /  /  /  /
90980-10294 3 STA Starter Signal Input This pin is used to determine if the engine is being cranked. The engine ECU can take action to allow the engine to start easier if it is aware that the engine is trying to be started. This pin is connected to battery voltage when the ignition switch is in START position.  
90980-10294 4 #10 No. 1 Injector Output Output This pin is used to control the No.1, No.3 & No.5 fuel injectors. The fuel injectors are electronically controlled by the engine ECU. This pin is connected to Ground inside the ECU as required to turn the No.1, No.3 & No.5 fuel injectors ON.  The fuel injectors should be wired with one side of the solenoid connected to battery voltage (Ignition switched, via the fuel injection resistor pack) and one side of the fuel injector connected to this ECU pin.  
90980-10294 5 E01 ECU Ground Input Ground Used to supply a Ground path to allow current to flow. This pin connects to Ground or the battery negative.  
90980-10294 6 STP Stop Light Switch Input
This pin is used to detect when the brake pedal is depressed. Used to exit deceleration fuel cut, etc.

This pin is connected to battery voltage when the brake pedal is depressed, the ECU pin is open circuit when the brake pedal is not depressed.

 
90980-10294 7 E1 ECU Ground Input Ground Used to supply a Ground path to allow current to flow. This pin connects to Ground or the battery negative via the engine block.  
90980-10294 8 IGT Igniter Trigger Signal Output This pin is used to control the ignition. The ignition timing is electronically controlled by the engine ECU. This pin is connected to +5V inside the engine ECU as required to trigger engine ignition.  Ignition is triggered on the high (+5V) to low (0V) transition.  
90980-10294 9 #20 No. 2 Injector Output Output This pin is used to control the No.2, No.4 & No.6 fuel injectors. The fuel injectors are electronically controlled by the engine ECU. This pin is connected to Ground inside the ECU as required to turn the No.2, No.4 & No.6 fuel injectors ON.  The fuel injectors should be wired with one side of the solenoid connected to battery voltage (Ignition switched, via the fuel injection resistor pack) and one side of the fuel injector connected to this ECU pin.  
90980-10294 10 E02 ECU Ground Input Ground Used to supply a Ground path to allow current to flow. This pin connects to Ground or the battery negative via the engine block.  
                 
Plug Pin Number Symbol Definition Input / Output What Why How Link
90980-10295 1 THW Water Temperature Sensor Input This pin is used to measure the temperature of the engine coolant. The engine coolant temperature has a significant effect on the engines operation, for example requiring more fuel during 'warm up' conditions. This pin connects to a thermistor that is installed at the engine coolant water outlet to the radiator on the front, upper, exhaust side of the engine to measure engine coolant temperature.  One side of the thermistor should be wired to this pin and one side of the thermistor should be wired to the engine ECU pin E2 (Ground).  
90980-10295 2 IGF Igniter Verification Signal Input This is pin is used to detect if ignition has taken place successfully. If no ignition is occurring and fuel injection continues the spark plugs can be fouled and backfires can occur in the exhaust, the igniter sends a signal to inform the engine so that it can stop fuel injection if successful ignition is not detected. This pin is connected to Ground by the Igniter for a short period of time after a successful ignition event has been detected.  
90980-10295 3  /  /  /  /  /  /  
90980-10295 4 NE Crank position sensor Input This pin is used to detect the speed and location of the engine crankshaft. The engine ECU needs to know the position of the engine so that it can accurately provide fuel and ignition. This pin connects to the engine distributor which outputs 24 reluctor pulse signals per distributor rotation.  
90980-10295 5 G1 Cam Position Sensor Input This pin is used to detect the location of the intake camshaft. The engine ECU needs to know the position of the engine so that it can accurately provide fuel and ignition. This pin connects to the engine distributor which outputs 2 reluctor pulse signals per distributor rotation.  Each signal is ~10° BTDC cylinder No.1.  
90980-10295 6  /  /  /  /  /  /  
90980-10295 7 G- Crank & Cam Position Sensor Ground Output This pin is used to detect the location of the crankshaft and the intake camshaft. The engine ECU needs to know the position of the engine so that it can accurately provide fuel and ignition. This pin connects to the engine distributor which outputs reluctor signals for both crank and intake camshaft position.  
90980-10295 8 ISCV2 Idle Speed Control Valve  Output This pin is used to open / close the Idle Speed Control Valve (ISCV) to allow more or less air to enter the engine as required to keep the desired engine idle speed There are a large number of items that effect idle speed (e.g. engine temperature,  electrical load, etc) an Idle Speed Control Valve allows the engine ECU to compensate and attempt to maintain the desired engine idle RPM. This pin is connected to Ground inside the ECU as required in a sequenced fashion with the other ISCVx pins to open / close the ISCV as required by the engine ECU.  The ISCV has two power pins which should be connected to battery voltage (Main EFI Relay switched).  
90980-10295 9 ISCV1 Idle Speed Control Valve  Output This pin is used to open / close the Idle Speed Control Valve (ISCV) to allow more or less air to enter the engine as required to keep the desired engine idle speed There are a large number of items that effect idle speed (e.g. engine temperature,  electrical load, etc) an Idle Speed Control Valve allows the engine ECU to compensate and attempt to maintain the desired engine idle RPM. This pin is connected to Ground inside the ECU as required in a sequenced fashion with the other ISCVx pins to open / close the ISCV as required by the engine ECU.  The ISCV has two power pins which should be connected to battery voltage (Main EFI Relay switched).  
90980-10295 10 E2 Sensor Ground Output Sensor ground. The throttle position and MAP sensors have a separate ground to ensure clear signals. This pin is connected to sensor Ground inside the engine ECU.  Do not connect this pin to chassis Ground.  
90980-10295 11 OX Oxygen Sensor Input This pin is used to determine the exhaust gas air fuel ratio. The engine ECU will aim for an air fuel ratio near stoichiometric (neither rich or lean) to enhance fuel economy under periods of low load. This pin connects to the signal output of the oxygen sensor that is mounted in the exhaust.  The factory oxygen sensor is a 'narrow band' oxygen sensor that outputs approximately 0V when the air fuel ratio is lean and approximately 1V when the air fuel ratio is rich.  The engine ECU will aim to keep the engine running at stoichiometric by alternating between very slightly rich and very slightly lean conditions, as the sensor is only a narrow band sensor this is a practical way to achieve (or very close to) the desired stoichiometric air fuel ratio.  
90980-10295 12 KNK Knock Sensor Input This pin is used to measure engine knock. Engine knock can occur if too much ignition timing and poor fuel are present, as engine knock can damage an engine the engine ECU used a knock sensor to detect and compensate for knock if is  detected. This pin connects to the signal output of the knock sensor which is mounted under the intake manifold, screwed into the side of the engine block.  The knock sensor is Grounded via the engine block.  
90980-10295 13 IDL Throttle Position Idle Switch Input This pin is used to detect when the throttle is in the idle (fully closed) position. Knowing when the throttle is fully  closed allows the engine ECU to have a known position allowing it to compensate for slight variation in the analogue signal. This pin is connected to Ground by a switch inside the throttle position sensor when the throttle is fully closed.  
90980-10295 14 VTA Throttle Position Sensor Input This pin is used to detect the position of the engine throttle. The measured position of the engine throttle is a useful parameter for engine operation, particularly in transient conditions such as acceleration. This pin measures the variable voltage from the throttle position sensor that represents how open / closed the throttle is.  
90980-10295 15 T Test mode enable Input This pin is used to select the test mode during which diagnostic codes are flashed on the check engine light . Used to help in diagnosing issues. This pin is connected to Ground to enable test mode.  
90980-10295 16 VF Voltage Feedback Output This pin is used to output diagnostic voltages that are related to the air fuel ratio and O2 sensor as well. Used to help in diagnosing issues. This pin outputs a diagnostic voltage related to fuel trim.  When the engine ECU pin T is connected to Ground and the TPS IDL contact is OFF (engine ECU pin IDL is not connected to Ground) this pin outputs 0V when the engine ECU detects a lean O2 condition and 5V when the engine ECU detects a rich O2 condition.  When the engine ECU pin T s connected to Ground and the TPS IDL contact is ON (engine ECU pin IDL is connected to Ground) this pin outputs 0V if no trouble codes are stored and 5V if trouble codes have been stored.  
90980-10295 17 ISCV4 Idle Speed Control Valve  Output This pin is used to open / close the Idle Speed Control Valve (ISCV) to allow more or less air to enter the engine as required to keep the desired engine idle speed There are a large number of items that effect idle speed (e.g. engine temperature,  electrical load, etc) an Idle Speed Control Valve allows the engine ECU to compensate and attempt to maintain the desired engine idle RPM. This pin is connected to Ground inside the ECU as required in a sequenced fashion with the other ISCVx pins to open / close the ISCV as required by the engine ECU.  The ISCV has two power pins which should be connected to battery voltage (Main EFI Relay switched).  
90980-10295 18 ISCV3 Idle Speed Control Valve  Output This pin is used to open / close the Idle Speed Control Valve (ISCV) to allow more or less air to enter the engine as required to keep the desired engine idle speed There are a large number of items that effect idle speed (e.g. engine temperature,  electrical load, etc) an Idle Speed Control Valve allows the engine ECU to compensate and attempt to maintain the desired engine idle RPM. This pin is connected to Ground inside the ECU as required in a sequenced fashion with the other ISCVx pins to open / close the ISCV as required by the engine ECU.  The ISCV has two power pins which should be connected to battery voltage (Main EFI Relay switched).  
 
 
 
 
 
 
 
 
 
Plug Pin Number Symbol Definition Input / Output What Why How Link
90980-10296 1 IGSW Ignition Switch Input This pin is used to determine if the ignition is ON. The engine ECU is turned on by this signal. This pin is connected to battery voltage when the ignition switch is in RUN and CRANK positions.  
90980-10296 2 BATT Battery Power Input This pin is used to supply constant battery power to the ECU. Constant battery power allows the engine ECU to retain error codes, fuel trims, etc. This pin is connected to battery voltage at all times.  
90980-10296 3 VC +5V Regulated Power Output This pin is used to supply +5V power to the throttle position and Air Flow Meter (AFM) sensors. The throttle position and AFM sensors require regulated and constant +5V to operate. This pin outputs regulated +5V to the throttle position sensors and the AFM sensor.  
90980-10296 4 VS Air Flow Input This pin is used to determine engine intake airflow. Engine intake airflow is a primary component in mass air flow fuel injection control algorithm that is used. This pin connects to the signal output of the AFM sensor which contains a potentiometer connected to a flap to convert engine air flow to a voltage.  
90980-10296 5 THA Intake Air Temperature Sensor Input This pin is used to measure the temperature of the engine inlet manifold air. The engine air temperature has an effect on the engines operation, such as reducing ignition timing if the intake air is very hot. This pin connects to a thermistor that is installed in the Air Flow Meter to measure air intake temperature.  One side of the thermistor should be wired to this pin and one side of the thermistor should be wired to the engine ECU pin E2 (Ground) via the Air Flow Meter.  
90980-10296 6  /  /  /  /  /  /  
90980-10296 7 SPD Speed Sensor Input This pin is used to determine vehicle speed. Vehicle speed is used in idle control, automatic transmission shift control, speed limiting etc.   Two speed sensors are used to provide a backup. This pin is connected to the combination meter speed output which outputs 20? pulses (Open collector square wave pulses) per speed sensor shaft revolution.  The combination meter receives its speed signal from the speed sensor which is located on the right, rear side of transmission and outputs 20 pulses (0V to Battery Voltage square wave pulses) per sensor shaft revolution (Note: dash is 637rev / km).  
90980-10296 8  /  /  /  /  /  /  
90980-10296 9 M-REL EFI Main Relay Output This pin is used to turn ON the Main EFI Relay which feeds power to the fuel pump, engine ECU, ISCV and engine VSVs, etc. ECU control of the main power relay allows the ECU to remain powered up after engine shutdown to fully open the ISCV. This pin is connected to battery voltage inside the ECU as required to turn the Main EFI Relay ON when the ignition switch is ON.  Note that this pin continues to output voltage for a few second after the ignition has been switched off to allow the ISCV to be fully opened by the ECU for the next engine start.  One side of the Main EFI Relay coil should be connected to this pin and one side of the Main EFI Relay coil should be connected to Ground.  
90980-10296 10 L3 Throttle Position Output Together the L1, L2 & L3 pins are used to output a digital representation of the throttle position. Throttle position is required by some sub control units such as the ABS & TRC ECU. The L1, L2 & L3 pins together output a modified Gray encoded digital signal.  Each pin outputs output either 0V or 5V.  Refer to L1, L2, & L3 page for details.  
90980-10296 11 L2 Throttle Position Output Together the L1, L2 & L3 pins are used to output a digital representation of the throttle position. Throttle position is required by some sub control units such as the ABS & TRC ECU. The L1, L2 & L3 pins together output a modified Gray encoded digital signal.  Each pin outputs output either 0V or 5V.  Refer to L1, L2, & L3 page for details.  
90980-10296 12 L1 Throttle Position Output Together the L1, L2 & L3 pins are used to output a digital representation of the throttle position. Throttle position is required by some sub control units such as the ABS & TRC ECU. The L1, L2 & L3 pins together output a modified Gray encoded digital signal.  Each pin outputs output either 0V or 5V.  Refer to L1, L2, & L3 page for details.  
90980-10296 13 +B EFI Main Relay Switched Power Input This pin is used to supply switched battery power to the ECU. Used to supply power. This pin is connected to battery voltage when the Main EFI Relay is energized to supply power to the ECU.  The Main EFI Relay is triggered by the engine ECU pin M-REL pin.   
90980-10296 14 +B EFI Main Relay Switched Power Input This pin is used to supply switched battery power to the ECU. Used to supply power. This pin is connected to battery voltage when the Main EFI Relay is energized to supply power to the ECU.  The Main EFI Relay is triggered by the engine ECU pin M-REL pin.   
90980-10296 15  /  /  /  /  /  /  
90980-10296 16  /  /  /  /  /  /  
90980-10296 17 E12 ECU Ground Input Ground Used to supply a Ground path to allow current to flow. This pin connects to Ground or the battery negative via the engine to body loom harness connector and the engine block.  
90980-10296 18 OIL Oil Pressure Sensor Input This pin connects to the engine mounted oil pressure sensor / switch. The exact function of this information to the Engine ECU is unknown. This pin is connected to ground via the engine mounted oil pressure sensor when the engine oil pressure is above the on pressure of the oil pressure switch.  
90980-10296 19 W Engine Warning Light (Check Engine Light) Output This pin is used to turn ON / OFF the check engine light. The check engine light comes on to inform of a detected engine issue. This pin is Grounded by the ECU as required to turn the Check Engine Light ON.  The check engine light should be wired with one side of the light connected to battery voltage (Ignition Switched) and one side of the light connected to this ECU pin.  Light ON = Error Condition, light OFF = Normal.  
90980-10296 20 A/C Air Conditioning (AC) Signal Input This pin is used to signal the the AC status. Having an AC status input allows the engine ECU to modify engine parameters such as the engine idle speed when the AC is ON. This pin is connected to battery voltage when the AC is ON.  
90980-10296 21  /  /  /  /  /  /  
90980-10296 22 C-MAX Engine Temperature? Output Engine temperature could be sent to the Automatic Transmission ECU (Does not look to be connected).
It is my understanding that the Automatic Transmission ECU can vary the shift characteristics taking into account the engine temperature? 2-3V = Engine coolant temperature less than 35°C, 0V = engine coolant temperature between 35-60°C, 4-6V engine coolant temperature above 60°C.  
90980-10296 23 E11 ECU Ground Input Ground Used to supply a Ground path to allow current to flow. This pin connects to Ground or the battery negative via the engine to body loom harness connector and the engine block.  
90980-10296 24 E22 Sensor Ground Output Sensor ground. The throttle position and MAP sensors have a separate ground to ensure clear signals. This pin is connected to sensor Ground inside the engine ECU.  Do not connect this pin to chassis Ground.  

 

MZ12 Toyota Soarer 6MGEU Engine Loom to Body Loom Pinout

 

MZ12 Toyota Soarer 6MGEU 90980-10330 Engine Loom to Body Loom Plug (Yellow)

This plug is located inside the passenger glove box area and mates with male connector 90980-XXXXX.

 

 

 

Pin Symbol Definition Input / Output
(To engine = Input)
(From engine = Output)
Description
1  
Ground (Condition Indicator Computer / Multivision system)
 
The body loom side of this pin needs to be connected to the Condition Indicator Computer (centre of dash) or the Multivision system  located in the boot (Multivision equipped vehicle) so that diagnostic codes can be automatically read using the engine ECU T pin.

 

The engine loom side of this pin is connected to ground via the engine block.
2  
Ground (E11, E12 and Oxygen Sensor Cable Screen) Output
The body loom side of this pin needs to be connected to engine ECU pins E11, E12 and the exhaust mounted oxygen sensor cable screen.

The engine loom side of this pin is connected to ground via the engine block.
3 Engine ECU: VC TPS Power Input

The body loom side of this pin needs to be connected to the engine ECU VC pin.

 

The engine loom side of this pin connects to the TPS.

4 Engine ECU: +B Main EFI Relay Switched Power Input

The body loom side of this pin needs to be connected to main EFI relay switched power (+B).

The engine loom side of this pin connects to the ISCV and engine mounted service connectors (Note the engine ECU +B pins are supplied power on a different connector).

5 CCRO
Exhaust Gas Temperature Sensor
Output

The body loom side of this pin needs to be connected to the Exhaust Gas Temperature Sensor located near the catalytic converter.

 

The engine loom side of this pin is broken out to a connector to provide a point for diagnostics to be undertaken.

6 Engine ECU: STP
Stop Light Switch Input The body loom side of this pin needs to be connected to the switched side of the brake light switch.

The engine loom side of this pin connects to the engine ECU STP terminal.
7 Engine ECU: NSW / CSW
 Neutral Switch / Clutch Switch Input

The body loom side of this pin needs to be connected to an ignition switched power source that supplies battery voltage when the ignition switch is in the START and,

-The automatic transmission P or N position switch is in the P or N position for automatic transmission vehicles

or,

-The clutch pedal is depressed for manual transmission vehicles fitted with a clutch pedal switch.

When voltage is not supplied this pin should be earthed via the starter motor solenoid.

 

The engine loom side of this pin connects to the engine ECU NSW / CSW pin.

8 Engine ECU: OX Oxygen Sensor Output The body loom side of this pin needs to be connected to the exhaust mounted oxygen sensor.

The engine loom side of this pin connects to the engine ECU OX pin.
9 Engine ECU: T This pin is used to select the test mode during which diagnostic codes are outputted via the engine ECU pin W. Used to help in diagnosing issues.

The body loom side of this pin needs to be connected to the Condition Indicator Computer (center of dash) or the Multivision system  located in the boot (Mutlivision equipped vehicle) so that diagnostic codes can be automatically read.

 

The engine loom side of this pin connects to the engine ECU T pin.

10 Engine ECU: #10 No. 1 Injector Output Output This pin is used to supply the "Trip Computer" with fuel usage information (Injector Pulse Width). 

 

The body loom side of this pin needs to be connected to the Condition Indicator Computer (center of dash) or the Multivision system  located in the boot (MZ12 GT LTD) so that diagnostic codes can be automatically read.

 

The engine loom side of this pin connects to the engine ECU #10 pin

11   Engine Coolant Temperature Dash Sensor Output The body loom side of this pin needs to be connected to the coolant temperature gauge located in the dash.

The engine loom side of this pin connects to the one wire engine coolant temperature sensor located at the engine near the front, intake side of the engine.
12 Engine ECU: STA Starter Signal Input The body loom side of this pin needs to be connected to an ignition switched power source that supplies battery voltage when the ignition is in the START position.

The engine loom side of this pin connects to the engine ECU STA pin and the cold start fuel injector.
13

Engine ECU: IDL

Throttle Position Idle Switch Output The body loom side of this pin should be connected to the Cruise Control ECU and the Automatic Transmission ECU (automatic transmission).

The engine loom side of this pin connects to the engine mounted TPS IDL contact.
14  
Ground (AFM & Engine ECU E2 to E22 connection)
Output

The body loom side of this pins needs to be connected to the AFM E2 and engine ECU E22

 

The engine loom side of this pin connects to the engine ECU E2, THW E2 (Engine Coolant Temperature Sensor) and the TPS E2 pins.

 

 

 

MZ12 Toyota Soarer 6MGEU Wiring Diagrams

 

 

 

xZ1x Electrical Wiring Diagram Book 67207

xZ1x Electrical Wiring Diagram Book 67207.pdf

 

 

 

 

 

 

 

 

 

 

 

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