Honda Prelude 1993 Service Manual page 1220

Engine Coolant Temperature (ECTI Gauge
Gauge Test
NOTE: Reter to pag€ 23- 1 29 tor the circuit diaglam of
the engine coolant temperature (ECTI g8ugs.
'1.
Check the No. 13 (10 A) tuse in the under-dash
tuse/relay box before testing.
2.
Make sure the ignition switch is OFF, then discon-
nect the RED wire from the ECT sending unit 8nd
ground it with a jumper wire.
Turn the ignition switch ON. Check that the
segments of the ECT gauge light up.
CAUTION: Turn tho ignition switch OFF lm-
m€diately after the ssgmsnts light up. Failuro to do
so may damag€ the gaug6.
a lf the segments do not light up, check for an
open in the YEL or RED wire. lf the wire is OK,
replace the ECT gauge.
a lf the segments light up, check the sending unit.
Sending Unit Test
RED WIRE ECT SEI{DII{G UNIT
1 .
2 .
Disconn€ct the RED wire from the sending unit.
With the sngine cold, use an ohmmeter to measure
r€sistance b€tween the positive terminal and the
engine (ground),
REO
WIRE
4 .
POSITIVE TERMINAL
ECT SENDING UNIT
Check the temoerature of the coolant.
Run the engine and measu.e the change in
resistance with the engine at operating tempera-
ture (.adiator fan comes on).
5. lf the readings you get are substantially difterent
from the specitications above, replace the ECT sen-
ding unit.
--------.____/
Coolant
Tempgrature
1 3 3 0 F ( 5 6 . C )
(Engine cold)
1 8 5 0 F { 8 5 0 C ) -
2 ' t 2 0 F t 1 0 0 0 c l
Resistance (O)
'l42
4 9 - 3 2
23-142