Engine Speed Signal; Engine Immobiliser Syste M - Toyota COMPUTER-CONTROLLED SYSTEM Training Manual

ELECTRONIC CONTROL SYSTEM - Communications Signal s
7 . EHPS (ELECTRO-HYDRAULIC POWER
STEERING) SYSTEM COMMUNICA-
TIONS SIGNAL
When the engine coolant temperature or the
engine speed is extremely low, the load on the
alternator could become excessive when the
vane pump motor of the EHPS is driven .
To prevent this, the Power Steering ECU sends
this signal to the Engine ECU, which therefore
causes the ISC to increase the engine speed .
ELECTRICAL CIRCUITR Y
Power Steering ECU Engine EC U
OHP 4 1
REFERENCE
EHPS is a type of power steering in which the
vane pump is driven by an electric motor .
8 . ENGINE SPEED SIGNA L
This is the NE signal, which is input to the
Engine ECU, then undergoes waveform shaping
and is output to the TRC ECU, etc .
ELECTRICAL CIRCUITR Y
TRC ECU
Engine EC U
OHP 41
9 . ENGINE IMMOBILISER SYSTEM COM-
MUNICATIONS SIGNA L
The Engine ECU generates a rolling code based on
certain parameters, and sends it to the
Transponder Key ECU ( IMO terminal) .
Upon receiving the rolling code from the Engine
ECU, the Transponder Key ECU converts the roll-
ing code according to certain parameters, and
sends it to the Engine ECU (IMI terminal) .
If the correct signal is not sent by the Transponder
Key ECU, the Engine ECU will prohibit fuel injec-
tion and IGT signal, thus disabling the engine .
ELECTRICAL CIRCUITR Y
Transponder
Key ECU
EFII IMO
Engine EC U
EFIO IMI
47