Wacker Neuson Engine Starting System RD 12/RD 12A
wc_tx000746gb.fm 44
4.4 Checking the Crank Relay
Prerequisites Multimeter
Fully-charged (approximately 12V) battery
Functioning 20A main fuse
Functioning key switch
Background The coil of the crank relay is energized when the key switch is in the START posi-
tion.
Procedure Follow the procedure below to check the crank relay.
1. Open the hood and locate the crank relay (a).
2. Check the voltage between terminal 30 (red wire #40) and ground. This test
may be done at the plug (b) with it disconnected from the crank relay.
Is battery voltage (approximately 12V) measured?
3. With the key switch in the START position, check the voltage between terminal
86 (black wire #04) and ground. This test may be done at the plug (b) with it dis-
connected from the crank relay.
Is battery voltage (approximately 12V) measured?
4. With the key switch in the START position, check the voltage between terminal
87 and ground (red wire #35). For this test, the plug
(b) must be connected to
the crank relay. Position the plug as shown to allow access to terminal 87.
Is battery voltage (approximately 12V) measured?
The crank relay has now been checked.
Yes ____ No ____
Continue Repair red wire #40.
Yes ____ No ____
Continue Repair black wire #04.
Yes ____ No ____
The crank relay is OK. The crank relay has failed; replace it.
wc_gr004130
86
85
30
87
R 40
R 35
B 04
a
b
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