General Precautions of EFI System Maintenance
F-30
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
MIL Lamp On P-CODE Present MIL Lamp Off P-CODE Present
P0137 P0137
Maintenance tips:
The malfunction has been confirmed, and the
following problems may possibly exist
1) The circuit connected to Pin 55# of ECU and
36# of ECU in short circuit.
2) The circuit connected to Pin 55# of ECU short
circuit to ground
Maintenance tips:
The malfunction is not ultimately confirmed and it
may possibly be a random malfunction. Inspect the
following items:
1) Examine resistance between ECU Pin 55 #and
36#
2) Examine voltage on ECU Pin 55#
34. P0138 Downstream Oxygen Sensor Signal Circuit Voltage Over-High (Circuit Shorted
to Power Supply)
Description about Malfunction Cause:
After engine has been started, ECU will perform measurement on circuit voltage of downstream oxygen
sensor, and determine it to be the signal circuit of downstream oxygen sensor short to power supply, when
signal voltage is higher than 1.5V for a long time.
Schematic Circuit:
Malfunction Diagnostic Guide:
Required Equipment: (Diagnostic Instrument with EOBD Diagnostic Function, Digital Multimeter, and
Correct Circuit Diagram)
Mian relay
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