TOYOTA PREVIA 91-97 REPAIR MANUAL

2-2 ENGINE ELECTRICAL

ELECTRONIC SPARK ADVANCE SYSTEM

*f or information on understanding electricity and troubleshooting
electrical circuits, please refer to Section 6 of this manual.

General Information

I See Figure 1

The Electronic Spark Advance (ESA) system is used on all Toyota
Previas. The electronic ignition system offers many advantages :|ver the
conventional breaker points ignition system. By eliminating the loints,
maintenance requirements are greatly reduced. An electronic igr tion
system is capable of producing a much higher voltage which in urn aide
in starting, reduces spark fouling and provides emission contro
The ESA ignition system consists of a distributor with a signal gener-
ator, ignition coil (s), electronic igniter and a micro-computer called an
Electronic Contro! Module (ECM). The 2TZ-FZE engine also usefc a
Crankshaft Position (CKP) sensor. The ECM is programmed with data for
optimum ignition timing for a wide range of driving and operating con-
ditions. Using data provided by the various engine mounting se sors
(intake air volume, engine temperature, rpm, etc.), the ECM con erts the
data into a reference voltage signal and sends this signal to the Igniter
mounted inside the distributor. The signal generator receives a reference
voltage from the ECM and activates the components of the ignit jr. The
signal generator consists of three main components: the signal otor,
pick-up coil and the permanent magnet. The signal rotor revolves with
the distributor shaft, while the pick-up coil and permanent magriet are
stationary, as the signal; rotor spins the teeth on it pass a projection
leading from the pick-up coil. When this occurs, voltage is allowed to
flow through the system and fire the spark plugs. This process \,i
without physical contact or electrical arching; therefore, there is
to replace burnt or worn parts.

Diagnosis and Testing

' START TEST

I See Figures 2, 3, 4, 5 and 6

1. First, conduct a spark test as follows.


2. On the 2TZ-FZE engines, remove the exhaust pipe heat insulator.

CHECK RESISTANCE OF HIGH-TENSION

CORDS

Maximum resistance: 25 k:; per cord

[CHECK POWER SUPPLV TO "IGNITION COIL

1. Ignition switcn turn to ON.


2. Check that there is battery voltagi

CHECKResistance RESISTANCE (Cold]: OF IGNITION COIL

Primary 0.3 -0.6 U

Secondary 9 - 15 kQ

| CHECKAir gap. AIR GAP OF 0.2 - 0.4mm DISTRIBUTOR (0 008 - 0.016

CHECK IGT SIGNAL FROM ECU

[TRY ANOTHER IGNITER

Fig. 2 No start test chart—1991-93 models

Ignition Switch

AM2

Fusible Link

AM2 (20A)

Firing Order:

1-3-4-2

To Tachometer

Battery

Fig. 1 Schematic of the Electronic Spark Advance (ESA) system circuit