Simplicity AGCO Allis 2000 Series, Service & Repair Manual

Page: 105 / 312

7 - 37
7 Electrical System Service
Component Tests
F. Preheat Timer Test
The preheat timer energizes the glow plug relay for five
to ten seconds when the ignition key switch is initially
placed into the RUN or START position.
Tools:
a. 12 volt dc test lamp (A, Figure 66).
b. 12 volt dc power supply or battery (D).
c. Two to four test jumpers/wires with alligator clips
on the ends (C).
1. Connect one jumper from terminal D of the preheat
timer (B) to the negative (-) terminal of the power
supply or battery (D).
2. Use a test lamp (A) and connect one lead to terminal
C of the preheat timer (B) and the other lead to the
positive (+) terminal of the power supply or battery
(D).
NOTE: The test lamp is simulating the coil of the preheat
timer. The preheat timer is an electronic relay module
and the actual test lamp may not be a large enough load
for the module to turn on the test lamp. Be sure the lamp
is a 12 volt dc lamp and not an electronic testing lamp or
LED (light emitting diode) type of test lamp.
3. Connect one end of the jumper (C) to the positive (+)
Figure 38. Testing Preheat Timer
A. 12 Volt DC Lamp/Tester
C. Test Jumpers/Wires with Alligator Clips
B. Preheat Timer D. 12 Volt DC Battery (or Power Supply)
A B C
D
A B C
D
5-10
Sec.
terminal of power supply or battery (D) and the other
end to terminal A of the preheat timer (B).
The test lamp should illuminate between five and ten
seconds, then turn off. This test is simulating placing
the ignition key switch into the RUN position.
4. Connect one end of the jumper to the positive (+) ter-
minal of power supply or battery and the other end to
terminal B of the preheat timer.
The test lamp should illuminate and remain illuminat-
ed until the jumper is removed from terminal B of the
preheat timer. This test is simulating placing the igni-
tion key switch into the START position.
A
B
A
Test Lamp On
Test Light Off
Test Lamp On
B
Test A
Simulating key
switch in RUN
position
Test B
Simulating key
switch in START
position
C
C
D
D
Not
for
Reproduction