Troubleshooting; Power Unit - Suzuki DF150 Service Manual

3-72 ENGINE CONTROL SYSTEM

TROUBLESHOOTING

"
Before starting troubleshooting, read and follow the "PRECAUTION ON SYSTEM INSPECTION"
section on page 3-47.
In this section, troubleshooting procedures are based on the assumption that "Low pressure fuel system"
and "mechanical components (power unit, lower unit, etc.)" are normal.
NOTE:
For troubleshooting of "Starter motor will not run", see page (4-13).
CHART 1: SELF-DIAGNOSTIC CODE "3-4" MAP sensor
START
< Ignition switch "ON" >
Check "14" terminal voltage.
Is result OK? (See page 3-49.)
YES
< Ignition switch "ON">
Check "12" terminal voltage.
Is result OK? (See page 3-58.)
YES
Possible cause:
• ECM failure
• Wire continuity/connection failure
CHART 2: SELF-DIAGNOSTIC CODE "3-1" IAC system
START
<Ignition switch "OFF → ON">
Check IAC valve operation.
Is result OK? (See page 3-62.)
NO
<Ignition switch "OFF">
Check IAC valve resistance.
Is result OK? (See page 3-62.)
YES
<Ignition switch "ON">
Check "55" "56" "57" "58" terminal voltage.
Is result OK? (See page 3-48.)
YES
Possible cause:
• IAC valve failure (mechanical)
• ECM failure
• Wire continuity/connection failure
NO
ECM failure
NO
MAP sensor failure
YES
NO
NO NO
Possible case:
• Incorrectly by-pass air screw adjustment
• IAC passage failure
IAC valve failure
• Wire continuity/connection failure
• ECM failure