INSTRUMENTATION
SERVICE MANUAL NUMBER 22
Page 4D-22
90-860074--1 FEBRUARY 2002
TESTING
1. With engine COLD, remove wiring from switch/sender terminals. Note position on
switch/sender for terminal referred to as W.
78189
a
b
Top View
a -
Water Temperature Switch/Sender
b -
Terminal W - Audio Warning Switch Circuit
2. Refer to the proceeding and connect a continuity meter between switch terminal W and
sender hex case.
a. No continuity should exist.
b. If continuity exists, replace sender.
NOTICE
Read WARNING about switch and sender testing in Precautions at front of this section
before proceeding with tests.
3. To test switch circuit for closing (alarm ON ), as if coolant temperature rises above
operating specifications, follow instructions a. - g.
a. Remove the switch/sender.
b. Refer to top view of switch/sender in Step 1., and using suitable jumper leads
connect alarm terminal – to switch terminal W.
c. Then, using suitable jumpers and being careful to avoid short circuits, connect the
negative (–) of a 12 volt power source to sender case and the positive (+) to the +
on the alarm , as shown following.
d. Using suitable container, thermometer and heat source, suspend switch with tip in
sand.
