Alternator Fr Signal Circuit Troubleshooting - Honda S2000 Service Manual

ldle Control System
Alternator FR Signal Circuit Troubleshooting
1. Disconnect the alternator 4P connector.
2. Turn the ignition switch ON (ll)
3. Measure voltage between ECM connector
t e r m i n a l s B 2 0 a n d C 5 .
Wire side of female terminals
ls thete about 5 V?
YES Go to step 4.
NO Go to step 14.
4. Turn the ignition switch OFF.
5. Reconnect the alternator 4P connector.
6. Start the engine. Hold the engine at 3,000 rpm with
no load (in neutral) until the radiator fan comes on,
then let it idle.
7. lvleasure voltage betlveen ECM connector
t e r m i n a l s 8 2 0 a n d C 5 .
Does the voltage decrease when the headlights
and rear window defogger are turned on?
YES The alternator FR signal is OK I
N O - G o t o s t e p 8 .
8. Turn the ignition switch OFF.
9. Disconnect ECI\4 connector C (3'lP).
10. Disconnectthe alternator 4P connector.
1 1 - 9 6
1 1 , Connect alternator 4P connector terminal No 4 to
body ground with a jumPer wire.
ALT 4P CONNECTOR
2
ALTF
3 4
(WHT/RED)
JUMPER WIRE
12.
Wire side of female terminals
Check for continuity between body ground and
ECM connector terminal C5.
ECM CONNECTOR C (31P)
ALTF (WHT/RED}
Wire side of female terminals
Is there continuitY?
YES Test the alternator (see step
'1
on page 4-23).
I
NO Repair open in the wire between the ECM (C5)
and the alternator.l
13. Turn the ignitlon switch OFF.
14. Disconnect ECM connector C (31P)
-r
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1
2 4 5
1
8 9
10
11
12 1 4
1 1
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2A 21 22
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'25
26 27 28
ZJ 30