BF135A•BF150A
5-93
3. A/F sensor line short circuit check
-1. Turn the ignition switch OFF. Disconnect the A/F sen-
sor connector and the ECM connector A.
-2. Check for the continuity between the test harness A-4
terminal and the engine ground.
Is there the continuity?
YES –
Repair short in the wire between the A/F sen-
sor and the ECM.
NO –
Go to the step 3.
-3. Check for the continuity between the test harness A-14
terminal and the engine ground.
Is there the continuity?
YES –
Repair short in the wire between the A/F sen-
sor and the ECM.
NO –
Replace the A/F sensor and recheck. If there
is any abnormality, substitute a known-good
ECM and recheck.
8. IDLE CONTROL SYSTEM
• Troubleshooting
When the MIL does not come ON but an engine failure of
either of the following symptoms occurs at the engine start
or during idling, inspect the system(s) and part(s) in the
numbered sequence.
• Hard to start
1. Vacuum line
2. IAC valve (P. 5-95)
• Engine starts but stalls soon.
1. Idle adjusting screw (P. 5-94)
2. IAC valve (P. 5-95)
3. Vacuum line
• Engine speed is higher than the specified
idle speed after warming up.
1. Vacuum line
2. IAC valve (P. 5-95)
3. Idle adjusting screw (P. 5-94)
• Engine speed is higher than the specified
trolling speed after warming up.
1. Neutral switch (P. 17-13)
2. Vacuum line
3. Idle adjusting screw (P. 5-94)
4. IAC valve (P. 5-95)
• Engine speed is lower than the specified
idling or trolling speed after warming up.
1. IAC valve (P. 5-95)
2. Idle adjusting screw (P. 5-94)
3. Vacuum line
• Engine speed is not stable during idling and
trolling.
1. IAC valve (P. 5-95)
2. Idle adjusting screw (P. 5-94)
3. Vacuum line
4. Neutral switch (P. 17-13)
A-4
A-14