Toyota Camry 1999 Electrical Troubleshooting Manual page 87

2. CONTROL SYSTEM
∗ SFI system
The SFI system monitors the engine condition through the signals, which are input from each sensor (Input signals from
(1) to (14) etc.) to the engine control module. The best fuel injection volume is decided based on this data and the
program memorized by the engine control module, and the control signal is output to TERMINALS #10, #20, #30 and
#40 of the engine control module to operate the injector. (Inject the fuel). The SFI system produces control of fuel
injection operation by the engine control module in response to the driving conditions.
∗ ESA system
The ESA system monitors the engine condition through the signals, which are input to the engine control module from
each sensor (Input signals from (1), (2), (4) to (12) etc.) the best ignition timing is detected according to this data and the
memorized data in the engine control module, and the control signal is output to TERMINALS IGT1 and IGT2. This
signal controls the igniter to provide the best ignition timing for the driving conditions.
∗ Idle Air Control system
The IAC system (Step motor type) increases the RPM and provides idling stability for fast idle–up when the engine is
cold and when the idle speed has dropped due to electrical load, etc. The engine control module evaluates the signals
from each sensor (Input signals (1), (4) to (8), (13) etc.), outputs current to TERMINALS ISCO and ISCC, and controls
the idle air control valve.
∗ Fuel pump control system
The engine control module operation outputs to TERMINAL FC and controls the CIR OPN relay. Thus controls the fuel
pump drive speed in response to conditions.
∗ EGR control system
The EGR cut control system controls the VSV (EGR) by evaluating the signals from each sensor which are input to the
engine control module (Input signals (1), (5), (6), (9) etc.) and by sending output to TERMINAL EGR of the engine
control module.
∗ A/C conditioning operation system
In addition to the conventional A/C cut control, the engine control module performs the air conditioning operation as well
since the A/C amplifier function is built in it.
3. DIAGNOSIS SYSTEM
With the diagnosis system, when there is a malfunctioning in the engine control module signal system, the malfunction
system is recorded in the memory. The malfunctioning system can then be found by reading the display (Code) of the
malfunction indicator lamp.
4. FAIL–SAFE SYSTEM
When a malfunction occurs in any system, if there is a possibility of engine trouble being caused by continued control based
on the signals from that system, the fail–safe system either controls the system by using data (Standard values) recorded in
the engine control module memory or else stops the engine.
SERVICE HINTS
E7 (A), E8 (B), E9 (C), E10 (D) ENGINE CONTROL MODULE
Voltage at engine control module wiring connector
BATT–E1 : Always 9.0–14.0 volts
+B–E1 : 9.0–14.0 volts (Ignition SW at ON position)
VC–E2 : 4.5– 5.5 volts (Ignition SW at ON position)
VTA–E2 : 0.3– 0.8 volts (Ignition SW on and throttle valve fully closed)
3.2–4.9 volts (Ignition SW on and throttle valve open)
PIM–E2 : 3.3– 3.9 volts (Ignition SW at ON position)
THA–E2 : 0.5–3.4 volts (Ignition SW on and intake air temp. 20°C, 68°F)
THW–E2 : 0.2– 1.0 volts (Ignition SW on and coolant temp. 80°C, 176°F)
STA–E1 : 6.0–14.0 volts (Engine cranking)
W–E1 : 9.0–14.0 volts (No trouble and engine running)
TE1–E1 : 9.0–14.0 volts (Ignition SW at ON position)
NSW–E1 : 0– 3.0 volts (Ignition SW on and Park/Neutral position SW position P or N position)
9.0–14.0 volts (Ignition SW on and except Park/Neutral position SW position P or N position)
IGT1, IGT2–E1 : Pulse generation (Engine cranking or idling)
#10, #20, #30, #40–E01, E02 : 9.0–14.0 volts (Ignition SW at ON position)
RESISTANCE AT ENGINE CONTROL MODULE WIRING CONNECTORS
(Disconnect wiring connector)
VC–E2 : 2.5–5.0 kΩ
THA–E2 : 2.21–2.69 kΩ (Intake air temp. 20°C, 68°F)
THW–E2 : 0.29–0.354 kΩ (Coolant temp. 80°C, 176°F)