Toyota COMPUTER-CONTROLLED SYSTEM Training Manual page 99

ESA - Ignition Circuitr y
Since the IGT signal from the ECU must be
distributed to three coils, the ECU outputs two
cylinder identification signals (IGDA and IGDB) .
The timing of each signal is shown in the chart
below .
The microprocessor is informed of when cylinder
No . 1 is at 100 BTDC by the next NE signal
following the G2 signal, and outputs the IGDA
and IGDB signals stored in memory in the
combination that corresponds to the order in
which the cylinders are fired, as shown in the
table to the right above .
The cylinder identification circuit in the igniter
distributes the IGT signal to the transistor drive
circuit that is connected to the relevant ignition
coil, based on the combination of these signals .
Switching of the IGDA and IGDB signals from 1
to 0 and from 0 to 1 is synchronized with the IGT
signal . Other circuits are the same as those in
the igniter for the conventional type .
3600
CA
720° C A
G1
G2
No . 1 BTDC 10 '
(compression)
0
SIGNAL S
CYLINDERS
IGDA IGD B
No . 1 and No . 6 0 1
No . 5 and No . 2 0 0
No . 3 and No . 4
1 0
OHP 6 4
/-IVV 1 C
High-voltage Diod e
On some models, since the ignition coils have
high-voltage diodes built into the secondary
side, judgment of the continuity cannot be con-
firmed by using an ordinary ohmmeter .
To spar k
plugs
From + B
L
To ignite r
u
High-voltage diod e
No . 1 ignition No . 5 ignition No . 3 ignition No . 6 ignitio n
IGT
,0
I
r
OHP 64
87