Acura NSX 1991 Manual page 238

Main Menu
Alternator (ALT) FR Signal
This signals the ECM when the Alternator (ALT) is charging.
Inspection of ALT FR Signal.
Check for a short in the circuit:
1. Disconnect the GRN 4P con-
nector from the ALT.
2. Turn the ignition switch ON (II).
3. Measure voltage between ECM
connector terminals D5 and
A26.
Is there approx. 5 V?
Check the operation of the ALT:
1. Turn the ignition switch OFF.
2. Reconnect the ALT GRN 4P
connector to the ALT.
3. Start the engine. Hold the
engine at 3,000 rpm with no
load (A/T in
M/T in neutral) until the radiator
fan comes on, then let it idle.
4. Measure voltage between ECM
connector terminals D5 and
A26.
Does the voltage decrease when
head lights and rear defogger are
turned on?
(To page 11-120)
Table of Contents
Check for a short in the wire:
1. Turn the ignition switch OFF.
2. Disconnect the negative bat-
tery cable from the battery.
3. Disconnect the ECM connec-
tor D (22P) from the ECM.
4. Check for continuity between
ECM connector terminal D5
and body ground.
Substitute a known-good ECM
and recheck. If prescribed voltage
is now available, replace the origi-
nal ECM.
position,
ALT FR signal is OK.
ECM CONNECTORS
WIRE SIDE OF FEMALE TERMINALS
Is there continuity?
Repair short in the wire between
the ECM (D5) and the ALT.