General Precautions of EFI System Maintenance
F-76
Malfunction Diagnostic Guide:
Required Equipment: (Diagnostic Instrument with EOBD Diagnostic Function, Digital Multimeter, and
Correct Circuit Diagram)
Step I: Use diagnostic instrument to read the malfunction information
Read Result I Read Result II
1. MIL Lamp On
2. MIL Off
P-CODE Present Malfunction Lamp Off P-CODE Present
P0650
P0650
The malfunction has been confirmed, and the
following problems may possibly exist
1) The circuit connected to Pin 31# of ECU
in open circuit
2) The circuit connected to Pin 31# of ECU
short to ground
3) The circuit connected to Pin 31# of ECU
short to power supply（MIL lamp ON）
The malfunction is not ultimately confirmed and it may
possibly be a random malfunction. Inspect the following
items:
1) Measure the electric resistance between the line of the
Pin 31# for connector of ECU and the malfunction
indicator lamp.
2) Measure the electric resistance between the Pin 31# for
connector of ECU and the ground.
3) Measure the electric resistance between the Pin 31# for
connector of ECU and the ignition switch
96. P0688 Improper Output Voltage of Main Relay
Description about Malfunction Cause:
After the ignition switch is turned on, ECU internal control module performs measurement over output
voltage of main relay, and if the measured voltage exceeds the reasonable voltage range preset in ECU, it is
determined to be the malfunction of improper voltage. Under such circumstance, neither MIL lamp nor SVS
lamp will be on.
97. P0691 Control circuit of cooling fan relay short to ground (low speed)
Description about Malfunction Cause:
After engine has been started, circuit control module of ECU examines voltage of cooling fan; if grounded
mode value detected, it is determined to be the malfunction of circuit of fan short to ground.
Schematic Circuit:
Battery
Main relay
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