Neutral Switch Malfunction; Tachometer Malfunction - Honda BF135A Manual

BF135A•BF150A

• Neutral Switch Malfunction

Engine speed does not increase in gear (BF150A only)
Perform neutral switch inspection (P. 17-13) and neutral
position adjustment (P. 3-25) before troubleshooting.
1. Neutral switch line check
-1. Start the engine and warm it up with the gear in neu-
tral.
-2. Disconnect the neutral switch 3P connector. Raise the
engine speed slowly and check that the engine speed
changes when it reaches approx. 4,500 rpm.
Does the engine speed change (Does VTEC func-
tion)?
YES – Replace the neutral switch.
NO – Go to the step 3.
-3. Stop the engine and connect the test harness.
Disconnect the ECM connector A, B and C.
-4. With the neutral switch 2P connector disconnected,
check for the continuity between the test harness B-13
terminal and the engine ground.
Is there the continuity?
YES – Repair short in the main harness between the
ECM and the neutral switch.
NO – Substitute a known-good ECM and recheck.
B-13

• Tachometer Malfunction

Tachometer does not function so that it corre-
sponds to the engine speed.
1. Tachometer power supply check
-1. Turn the ignition switch OFF and disconnect the
tachometer's connecting terminal.
-2. Turn the ignition switch ON and measure the voltage
between the harness side Black/Yellow terminal and
the Black terminal.
Is there the battery voltage?
YES – Perform "2. Tachometer pulse line check".
NO – Repair open in the meter harness.
2. Tachometer pulse line check
-1. Turn the ignition switch OFF and connect the test har-
ness.
Disconnect the ECM connector A, B and C.
-2. Check for the continuity between the test harness B-33
terminal and the engine ground.
Is there the continuity?
YES – Repair short in the main harness between the
tachometer and the ECM.
NO – Go to the step 3.
-3. Check for the continuity between the test harness B-33
terminal and the meter harness Gray terminal.
Is there the continuity?
YES – Substitute a known-good ECM and recheck.
NO – Repair open in the main harness between the
tachometer and the ECM.
B-33
METER HARNESS
TERMINAL
GRAY
B-33
5-70