Service Manual

Groundsmaster 4300--DPage 5 -- 32Electrical System
Start Relay
The start relay is used in the engine starting circuit.
When energized by the TEC controller, the start relay
provides a current path to energize the engine starter
solenoid. The start relay is attached to a frame bracket
under the hood next to the hydraulic pump drive shaft
(Fig. 34).
The TEC controller controls and monitors the operation
of the start relay. The relay and its circuit wiring should
be tested as a controller output with the Diagnostic Dis-
play before disconnecting and testing the relay (see
DiagnosticDisplay in the Troubleshootingsection of this
chapter). If the controller has detected a malfunction in
the start relay circuit, the Diagnostic lightcan be used to
identify the fault (see Diagnostic Light in the Trouble-
shooting section of this chapter).
Testing
1. Before disconnecting the s tart relay for testing, test
relayanditscircuitwiring as a TECcontrolleroutputwith
the Diagnostic Display (see Diagnostic Display in the
Troubleshooting section of this chapter).If the D iagnos-
tic Display verifies that the relay and circuit wiring are
functioning correctly, no further relay testing is neces-
sary.
2. If the Diagnostic Display determines that start relay
and circuit wiring arenot functioning correctly, park ma-
chine on a level surface, lower cutting decks, stop en-
gine, apply parking brake and remove key from ignition
switch. Open hood to gain access to relay.
3. Locate start relay and disconnect the machine wire
harness connector from the relay. Remove relay from
machine for easier testing.
NOTE: Prior to taking small resistance r eadings with a
digital multimeter, short the meter test leads together.
The meter will display a small resistance value (usually
0.5 ohms or less). This resistance is due to the internal
resistance of the meter and test leads. Subtract this val-
ue from the measured value of the component you are
testing.
4. Using a multimeter (ohms setting), measure coil re-
sistance between terminals 85 and 86 (Fig. 35). Resist-
ance should be between 70 and 90 ohms.
5. Connectmultimeter(ohms setting) leadsto relay ter-
minals 30 and 87. Ground terminal 86 and apply +12
VDC to terminal 85. The relay terminals 30 and 87
shouldhavecontinuityas+12VDCisappliedtoterminal
85.The relay terminals 30 and87 should nothave conti-
nuity as +12 VDC is removed from terminal 85.
6. Disconnect voltage from terminal 85 and multimeter
lead from terminal 87.
7. Connectmultimeter(ohms setting) leadsto relay ter-
minals 30 and 87A. With terminal 86 grounded, apply
+12 VDC to terminal 85. The relay terminals 30 and 87A
should not have continuity as +12 VDC is applied to ter-
minal 85. The relay terminals 30 and 87A should have
continuity as +12 VDC is removed from terminal 85.
8. When testing is completed, disconnect voltage and
multimeterleads from therelayterminals. Replace relay
if necessary.
9. Secure relay to machine and connect machine wire
harness connector to relay.
10.Lower and secure hood.
Figure 34
1. Pump drive shaft 2. Start relay
2
1
Figure 35
86
85
87A 87
30
2
1
3
4
1. Coil terminal
2. Common terminal
3. Normally closed term.
4. Normally open term.
1