Starter Replacement Determination - Borg Warner Delco Remy 28MT Diagnostic Procedures Manual

3-19. TEST PROCEDURE.
Magnetic switch that does not close or drops out too soon
can be caused by high resistance or open circuit in the control
circuit.
Leave the S lead disconnected to prevent engine from cranking
during these tests.
Connect
1. Digital voltmeter set on battery voltage scale to two small
terminals on magnetic switch. If magnetic switch has only one
small terminal, use switch bracket for other connection.
Test
1. With key on, push start button. Listen for click that signifies
magnetic switch closing. Note and record voltmeter reading V(13).
2. If magnetic switch closed (click detected or voltage at both
large switch terminals) and voltage V(13) is within 1.0 volt (2.0
volts for 24-volt system) of battery voltage V(12), this circuit is
okay.
3. If magnetic switch does not close and voltage V(13) is within
1.0 volt (2.0 volt for 24-volt system) of battery voltage V(12),
replace magnetic switch and retest.
4. If voltage V(13) is more than 1.0 volt (2.0 volt for 24-volt
system) below battery voltage, move the voltmeter lead on the
magnetic switch ground to frame or motor ground terminal. With
key on, push start button and read voltage V(14). If voltage V(14)
is within 1.0 volt (2.0 volts for 24-volt system) of battery voltage,
repair magnetic switch ground lead or connections. If not, replace
voltmeter ground lead at magnetic switch ground terminal.
5. Repeat step 4, moving voltmeter plus lead to the following
locations and measuring the specified voltages with the key on
and the push-button depressed.
If any voltage is not within 1.0 volt (2.0 volts for 24-volt system) of
battery voltage, repair or replace the wire or component specified
and retest:
V(15)-wire between push-button and magnetic switch
V(16) push-button
V(17) wire between push-button and key switch
V(18) key switch
V(19) wire between key switch and solenoid BAT terminal
3-20. TEST COMPLETION.
all tests have been completed satisfactorily, reconnect lead to S
terminal on starter solenoid so that engine can be started.
delcoremy.com
NOTE
NOTE
Remove voltmeter from vehicle. If
MAGNETIC
SWITCH
VOLTAGE (13)
V(16)
V(19)
V(14)
BATTERY
CABLE
VOLTAGE (12)
FIGURE 3-7. Magnetic Switch
Circuit Test
3-21. STARTER REPLACEMENT
DETERMINATION
Up to this point, the batteries and starter wiring have been
checked. The following additional checks should be made before
considering starter replacement, and finally, the criteria for starter
replacement, if necessary.
3-22. COLD WEATHER CRANKING.
magnetic switch also can fail to hold during cold weather starting
and low voltage, even though the switches and circuits tested
okay at higher temperatures. This condition will sound as though
the starter is failing to stay engaged with the engine. It is caused
by the cold weather low voltage of the system releasing the
electrical connection of the magnetic switch. To test for this
condition, proceed as follows:
Test
Large terminal studs on magnetic switch are at battery voltage.
Engine should crank when jumper is connected.
1. With key switch on, press start button and have assistant
clamp heavy battery jumper cable between two large studs on
magnetic switch. Engine should crank.
2. Immediately remove jumper to stop engine cranking.
3. If engine starts with jumper in place, replace magnetic switch.
IGNITION
PUSH
BUTTON
V(15)
V(17)
V(18)
DP-1025
Starter circuits with a
CAUTION
Page 17