Audio Warning System; Alarm - Mercury MerCruiser D2.8L D-Tronic Service Manual

SERVICE MANUAL NUMBER 22

Audio Warning System

The Audio Warning System is divided into two separate circuits. Both circuits have an
individual audio warning alarm that does NOT include any time delay.
One circuit consists of the engine water temperature switch and related wiring. If this switch
is activated (closed) during the operation of the engine, the alarm will sound and the Engine
System Monitor panel light will be illuminated until the problem is corrected or the electrical
system is shut off (key switched "OFF").
The other circuit consists of the engine oil pressure switch, the transmission temperature
switch (Inboard models) or the gear lube monitor bottle switch (Sterndrive models) and
related wiring. These switches are connected to the audio warning alarm. Likewise, the
Engine System Monitor panel light is illuminated whenever the respective switch is activated
(closed) until the problem is corrected or the electrical system is shut off (key switched
"OFF").
The function of an audio warning alarm can be tested by holding the toggle lever of the Audio
Test switch, on the Engine System Monitor Panel, DOWN momentarily, with the key switch
in the "RUN" position. If the alarm sounds it is operable.

Alarm

The following test involves the use of electricity. Failure to follow appropriate
procedures can cause burns or shock which can result in severe personal injury or
death.
TESTING
1. If the alarm does not sound:
a. Disconnect bullet connectors from suspect alarm.
b. Connect a 12 volt positive (+) jumper wire to where the positive (+) wire was
c. Connect the remaining wire to a clean, unpainted ground or negative (–) connection
d. If the alarm does not sound, replace it.
2. If the alarm worked in Step 1., reconnect the wires and do the following.
a. Remove the harness wires at the switches involved and briefly jumper the wire ends
b. If the alarm sounds, the problem is in the switch. Refer to Testing individual switches
3. If the alarm did not sound in Step 2., refer to wiring diagrams and check wires or
connectors to the individual switches.
4. Repair as needed.
90-860074--1 FEBRUARY 2002
connected.
using a jumper wire.
together. With the key switch in the RUN position, the alarm should sound.
as follows, and test the suspect switch. Replace as instructed.
WARNING
INSTRUMENTATION
Page 4D-19