Honda Acura NSX 1991 Service Manual page 1204

Dashlight Brightness Control
-Control Unit Input Test
Disconnect the 7-P connector from the control unit.
Make the following input tests at the harness pins.
If all tests prove OK, yet the dashlights still cannot be
controlled, check the connector for a good connection.
If OK, substitute a known-good control unit and recheck.
DASHLIGHT
BRIGHTNESS
CONTROL UN
7-P CONNECTOR
No. Terminal
Test condition
Under all conditions
1
BLK
Lighting switch ON.
2
Lighting switch ON.
3 RED
Adjusting dial rotated.
4 and
Test: desired result
Check for continuity to
ground: should be continuity.
Check for voltage to ground:
should be battery voltage.
Attach to ground: dashlights
should come on full bright.
Check for resistance between
the RED/GRN and REDANHT
terminals: should vary from 0
to 24,000 ohms as the dial is
rotated.
side
Possible cause (if result is not obtained)
Poor ground (G401, G402)
l
An open in the wire.
l
Blown No. 38 (I 5A) fuse.
l
Faulty taillight relay.
l
Faulty lighting switch.
l
An open in the wire.
l
An open in the REDIBLK or RED
l
wire.
Faulty controller.
l
An open in the wire.
l