The communication signals are sent among different ECUs and are used to make operational adjustments for each other.
1. TRC (Traction Control) system communication signal
The throttle opening (VTA1 and VTA2) signals are measured by the main and sub throttle position sensors and sent to the skid control ECU from the engine ECU. Conversely the TR signal is sent to the engine ECU from the skid control ECU to inform that the traction control is operating. When the skid control ECU outputs the TR signal, the engine ECU performs a variety of corrections related to the traction control, such as retarding the ignition timing.
2. ABS (Anti-Lock Brake System) communication signal
This signal is output when the ABS system is operating. It is used for fuel cut-off control and, when necessary, reduces the engine brake effect.
3. EHPS (Electro-Hydraulic Power Steering) system communication signal
When the engine coolant temperature or engine speed are extremely low, the EHPS vane pump motor operates, which might cause an excessive alternator load. To avoid this, the power steering ECU sends this signal to the engine ECU to have the ISC increase the idling speed.
4. Cruise control system communication signal
This signal is used to request the retarding of the ignition timing and is sent to the engine ECU from the cruise control ECU.
5. Engine speed signal
The engine speed signal is the NE signal, and input in the engine ECU. Then, its waveform is rectified so that it can be output to the skid control ECU and etc.
6. Engine immobiliser system communication signal
The engine ECU communicates with the transponder key ECU or the transponder key amplifier to ensure that the engine can only be started by an ignition key having the same ID as that registered in the engine ECU or transponder key ECU. When an attempt is made to start the engine using a key other than one with the registered ID, the engine ECU prohibits the fuel injection and ignition to prevent the engine from starting.
7. Throttle opening angle signal
The throttle opening (VTA) signal from the throttle position sensor is processed by the engine ECU, and then is combined with the L1, L2, and L3 signals and sent to the ECT ECU, suspension control ECU, and other systems.
8. Multiplex communication system communication signals
For the communication signals from (1) to (8), only the signals required by the various communicating ECUs are sent and received. In vehicles that use the multiplex communication system, the engine ECU, A/C ECU, theft deterrent ECU, combination meter, and etc., construct around the gateway ECU and body ECU. This allows the sensor signals required by the ECU to be received via another ECU not involved with the signal in the communication network. The engine ECU can also receive the required sensor signals from another ECU or can also pass along signals required for other ECUs through its MPX1 and MPX2 terminals.
OtherGasoline Engine Communication Signals
Gasoline Engine Communication Signals
The communication signals are sent among different ECUs and are used to make operational adjustments for each other.
1. TRC (Traction Control) system communication signal
The throttle opening (VTA1 and VTA2) signals are measured by the main and sub throttle position sensors and sent to the skid control ECU from the engine ECU. Conversely the TR signal is sent to the engine ECU from the skid control ECU to inform that the traction control is operating. When the skid control ECU outputs the TR signal, the engine ECU performs a variety of corrections related to the traction control, such as retarding the ignition timing.
2. ABS (Anti-Lock Brake System) communication signal
This signal is output when the ABS system is operating. It is used for fuel cut-off control and, when necessary, reduces the engine brake effect.
3. EHPS (Electro-Hydraulic Power Steering) system communication signal
When the engine coolant temperature or engine speed are extremely low, the EHPS vane pump motor operates, which might cause an excessive alternator load. To avoid this, the power steering ECU sends this signal to the engine ECU to have the ISC increase the idling speed.
4. Cruise control system communication signal
This signal is used to request the retarding of the ignition timing and is sent to the engine ECU from the cruise control ECU.
5. Engine speed signal
The engine speed signal is the NE signal, and input in the engine ECU. Then, its waveform is rectified so that it can be output to the skid control ECU and etc.
6. Engine immobiliser system communication signal
The engine ECU communicates with the transponder key ECU or the transponder key amplifier to ensure that the engine can only be started by an ignition key having the same ID as that registered in the engine ECU or transponder key ECU. When an attempt is made to start the engine using a key other than one with the registered ID, the engine ECU prohibits the fuel injection and ignition to prevent the engine from starting.
7. Throttle opening angle signal
The throttle opening (VTA) signal from the throttle position sensor is processed by the engine ECU, and then is combined with the L1, L2, and L3 signals and sent to the ECT ECU, suspension control ECU, and other systems.
8. Multiplex communication system communication signals
For the communication signals from (1) to (8), only the signals required by the various communicating ECUs are sent and received. In vehicles that use the multiplex communication system, the engine ECU, A/C ECU, theft deterrent ECU, combination meter, and etc., construct around the gateway ECU and body ECU. This allows the sensor signals required by the ECU to be received via another ECU not involved with the signal in the communication network. The engine ECU can also receive the required sensor signals from another ECU or can also pass along signals required for other ECUs through its MPX1 and MPX2 terminals.
OtherGasoline Engine Communication Signals
1. Stop lamp switch
The signal from the stop lamp switch is used to detect brake operation. The STP signal voltage is the same as the voltage supplied to the stop lamp as shown in the illustration.
2. EGR gas temperature sensor
The EGR gas temperature sensor is installed inside the EGR valve and uses a thermistor to measure the EGR gas temperature.
3. Fuel control switch or connector
The fuel control switch or connector notifies the engine ECU of whether the gasoline that is being used is regular or premium.
HINT:
Some models use a fuel control connector in place of a fuel control switch. This connector should be connected when premium gasoline is used, and is disconnected when regular gasoline is used. In other models, this is reversed. For information regarding the connector position or the regular/premium gasoline switching method, refer to the Owners Manual.
4. Water temperature switch
The water temperature switch is attached to the cylinder block, and turns ON when the coolant temperature become high.
5. Clutch switch
The clutch switch is under the clutch pedal and detects whether or not the clutch pedal is being fully depressed.
6. HAC (High-Altitude Compensation) sensor
The HAC sensor detects changes in the atmospheric pressure. The construction and operation are the same as those of the manifold pressure sensor. This sensor is sometimes in the engine ECU and sometimes outside of it. When driving at high altitude, the atmospheric pressure decreases as does the air density. Thus, L-type EFI engines, except those with hot-wire type air flow meters, tend to make the air-fuel mixture rich. The HAC sensor compensates for this deviation in the airfuel ratio.
7. Vapor pressure sensor
The vapor pressure sensor measures the pressure of the fuel vapor in the fuel tank. The basic construction and operation of the sensor are the same as those of the manifold pressure sensor. Unlike the output characteristic of that sensor, however, the vapor pressure sensor can detect slight changes in vapor pressure.
8. Turbocharging pressure sensor
The turbocharging pressure sensor detects the intake manifold pressure that is charged by the turbocharger. The basic construction and operation of the sensor are the same as those of the manifold pressure sensor. If the intake manifold pressure charged in the turbocharger becomes extremely high, the engine ECU will cut the fuel supply to protect the engine.
9. Oil pressure switch
The oil pressure switch signal is used to determine the low engine oil pressure. The oil pressure signal is used to control the ISC system. When the oil pressure is low, the lubrication and cooling of the engine components will be hindered. Therefore, the engine ECU will increase idling speed, etc., to restore the oil pressure to the normal level.
10.Kick-down switch
The kick-down switch is also called the full-throttle switch, and it is directly installed beneath the floor panel of the accelerator pedal.
Diagnostic Terminal
When the engine ECU stores a DTC (Diagnostic Trouble Code) in memory, the DTC must be checked and repairs must be performed. The DLC contains a DLC3 SIL terminal, which is required to display the DTC to communicate directly with the engine ECU when the handheld tester is used, TE1, TE2, E1, TC and CG terminals which cause the MIL to flash.